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Personal Communications Library For the C Language (PCL4C) USERS MANUAL Version 5.0 November 20, 1995 This software is provided as-is. There are no warranties, expressed or implied. Copyright (C) 1995 All rights reserved MarshallSoft Computing, Inc. Post Office Box 4543 Huntsville AL 35815 Voice : 205-881-4630 FAX : 205|880|0925 BBS : 205-880-9748 email : msc@traveller.com Anon FTP : ftp.traveller.com /pub/users/msc web : www.traveller.com/~msc/ _______ ____|__ | (R) --+ | +------------------- | ____|__ | Association of | | |_| Shareware |__| o | Professionals --+--+ | +--------------------- |___|___| MEMBER PCL4C Users Manual Page 1 C O N T E N T S Chapter Page 1.0 Introduction................................................3 1.1 User Support............................................4 1.2 ASP Ombudsman...........................................4 1.3 A Typical Application...................................5 1.4 Installation............................................6 2.0 Library Organization........................................7 2.1 Configuration...........................................7 2.2 Initialization & Termination............................7 2.3 Modem Control & Status..................................8 2.4 Serial I/O..............................................8 2.5 Error Detection.........................................9 2.6 General Support.........................................9 3.0 Library Overview...........................................10 3.1 Memory Models..........................................10 3.2 Protected Mode.........................................11 3.3 Compilers Supported....................................13 3.4 Using the Library......................................13 3.5 Application Notes......................................14 3.5.1 Terminal Programs................................14 3.5.2 Door Programs....................................14 3.5.3 BBS Programs.....................................14 3.6 Compiling & Linking....................................15 4.0 Talking to Your Modem......................................16 4.1 Modem Standards........................................16 4.2 Flow Control...........................................17 4.2.1 Software Flow Control (XON/XOFF).................17 4.2.2 Hardware Flow Control (RTS/CTS)..................17 4.3 MODEM_IO functions.....................................17 4.4 Modem Initialization...................................18 5.0 Problems...................................................19 6.0 Serial Communications......................................20 6.1 Communications Basics..................................20 6.2 Standard Port Addresses................................21 6.3 Running 3 or 4 Ports Concurrently......................22 6.4 Using Multiport Cards..................................23 6.4.1 The DigiBoard....................................23 6.4.2 The BOCA Board...................................23 6.5 Transmitter Interrupts.................................24 6.6 RS232 Signals..........................................25 6.7 National INS8250, INS16450, and INS16550 UARTs.........26 6.8 Register Summary.......................................27 7.0 Example Programs...........................................29 7.1 MINIMAL................................................29 7.1 SIMPLE.................................................29 7.2 LOGIN..................................................29 7.3 SPAWN & DOOR...........................................29 7.4 SELFTEST...............................................29 8.0 Legal Issues...............................................30 8.1 Registration...........................................30 8.2 License................................................30 8.3 Warranty...............................................31 9.0 Summary....................................................32 9.1 Revision History.......................................32 9.2 Function Summary.......................................34 9.3 Further Reading........................................34 10.0 Other MarshallSoft Computing products for C................35 10.1 The Personal Protocol Library for C...................35 10.2 The EMS Expanded Memory Library for C.................35 PCL4C Users Manual Page 2 1.0 Introduction The Personal Communications Library for the C Language (PCL4C) is an asynchronous communications library designed for experienced software developers programming in C/C++. Five compilers are supported: Microsoft C, Quick C, Borland C, Turbo C, and MIX Power C. An IBM PC/XT/AT or compatible is required. The PCL features: o Supports PROTECTED MODE. o SMALL, COMPACT, MEDIUM, and LARGE memory models. o 38 communications and support functions. o Supports the high performance 16550 UART. o Supports the PC/4 and PC/8 DigiBoard. o Supports the BOCA BB1004, BB1008, and BB2016 boards. o Supports hardware (RTS/CTS) flow control. o Interrupt driven transmitter & receiver. o Supports 300 baud to 115,200 baud. o Use IRQ2 through IRQ15 with any UART address. o Supports COM1 through COM8 (through COM20 with multiport boards) o Adjustable receive queues from 8 bytes to 32 KB. o Control-BREAK error exit. o 18 communications error conditions trapped. o Allows 4 ports to run concurrently (more with multiport boards). o Complete modem control & status. o Written in assembly language for small size & high speed. o Terminal program featuring ASCII (with XON/XOFF), XMODEM, YMODEM, & YMODEM-G. Why should you buy PCL4C ? Several good reasons are: COMPLETE - PCL4C is complete since it provides absolute control of the serial ports (including the high performance INS16550). COMPACT - PCL4C is very compact at less than 10 KB. Your application doesn't carry a lot of excess code. FAST - PCL4C is fast since it will run at 38400 baud on even slow 8088 PCs (4.77 MHZ) and at 115200 baud on most everything else. SUPPORT - If you get stuck, you talk to the programmer that wrote the code, not a person hired to answer the phone. BBS - A BBS is available (2400 to 14400 baud, N81) in order to provide immediate support as necessary. NEWSLETTER - We publish a quarterly newsletter "Comm Talk", which discusses serial communications problems and solutions. PRICE - You get PCL4C for a very reasonable price! UPGRADES - Once you buy PCL4C, you can always update to the most recent version very inexpensively ($20 plus shipping). PCL4C Users Manual Page 3 1.1 User Support We want you to be successful in developing your applications using PCL4C! We depend on our customers to let us know what they need in a communications library. This means we are committed to providing the best communications library that we can. If you have any suggestions or comments, please let us know! We provide customer support for registered customers by voice, FAX, BBS, email, and US mail. We provide limited support for unregistered users by voice, email, and BBS only. If you are having a problem using PCL4C, call us at 205-881-4630 between 1:30 PM and 9:30 PM (CST) Monday through Friday. You can also call at other times and leave a message, and call back later for a reply. Registered users (ONLY) can also FAX us at 205-880-0925 at any time (24 hours). However, we can only answer questions with respect to using the PCL4C library. We cannot help you program your application, but we'll be glad to discuss it with you. You may also call our User Support BBS (2400 to 14400 baud, no parity, 8 data bits, 1 stop bit) at 205-880-9748 and leave a message (address it to the SYSOP). We will usually have a reply ready for you within 24 hours. The BBS is available 24 hours per day. All files are in standard ZIP format. The BBS will contain the latest shareware version of all MarshallSoft Computing products as well as related files such as: BUGS.ZIP - Bug report. PRODUCTS.ZIP - List of all shareware products. The MarshallSoft Computing, Inc. newsletter "Comm Talk" is published quarterly. It discusses various communications problems and solutions using PCL4C as well as related information. The latest copy of our newsletter can be found on our support BBS, anonymous FTP site, or on our Web site. BBS : 205-880-9748 (look in file area "Newsletters") Anon FTP : ftp.traveller.com (directory /pub/users/msc) Web site : www.traveller.com/~msc/ 1.2 ASP Ombudsman MarshallSoft Computing, Inc. is a member of the Association of Shareware Professionals (ASP). ASP wants to make sure that the shareware principle works for you. If you are unable to resolve a shareware-related problem with an ASP member by contacting the member directly, ASP may be able to help. The ASP Ombudsman can help you resolve a dispute or problem with an ASP member, but does not provide technical support for members' products. Please write to the ASP Ombudsman at 545 Grover Road, Muskegon, MI USA 49442-9427, Fax 616-788-2765, or send a CompuServe message via CompuServe Mail to ASP Ombudsman 70007,3536. PCL4C Users Manual Page 4 1.3 A Typical Application In general, there are two classes of applications that use a communications library like PCL4C - those that use a modem to connect to the outside world and those that connect directly to a peripheral device. In either case, a typical application program using PCL4C might look like the following code outline: +---------------------------------------------------+ | #include "pcl4c.h" | | | | void main(void) | | { | | ... | | | | /* initialize serial comm system */ | | SioRxBuf(Port,AllocSeg(1024),Size1024); | | SioTxBuf(Port,AllocSeg(128),Size128); | | SioParms(Port,NoParity,OneStopBit,WordLength8); | | SioReset(Port,Baud2400); | | | | ...application code... | | | | /* terminate serial comm system */ | | SioDone(Port); | | } | +---------------------------------------------------+ In the above example, SioRxBuf is called to set up the a 1024 byte receive buffer; SioTxBuf is called to set up a 128 byte transmit buffer; SioParms is called to set up the parity, stop bit count, and word length; SioReset is called to set the baud rate to 2400 and reset the UART (Univeral Asynchronous Receiver / Transmitter). The function AllocSeg allocates a buffer of specified size on the far heap and returns the segment SEG such that SEG:0 points to the buffer. The function AllocSeg is part of the example code and can be found in the file ALLOCSEG.C. Before leaving your application, SioDone is called to restore the prior state of the serial communications system. If you are using a modem, you also need to be concerned about initializing your modem correctly and handling any required flow control. Refer to the "Talking to Your Modem" chapter for detailed information. The communication library has been pre-assembled to library files: PCL4C_S.LIB : Small memory model. PCL4C_C.LIB : Compact memory model. PCL4C_M.LIB : Medium memory model. PCL4C_L.LIB : Large memory model. PCL4C_P.LIB : Protected mode. [Large model]. PCL4C_S.MIX : MIX PowerC small memory model. PCL4C_M.MIX : MIX PowerC medium memory model. PCL4C_L.MIX : MIX PowerC large memory model. PCL4C Users Manual Page 5 1.4 Installation (1) Before installation of PCL4C, your C compiler should already be installed on your system and tested. If you are not familiar with makefiles, refer to your compiler manual. If you are using the interactive environment for Quick C or Turbo C, be sure to compile with the memory model corresponding to the PCL4C library used, and include the correct library in the project file. Examine the file "FILES.LST" for a list of all the distribution files. (2) Make a backup copy of your distribution disk. Put your original distribution disk in a safe place. (3) Create a work directory on your work disk (normally your harddisk). For example, to create a work directory named PCL4C, we first log onto the work disk and then type: MKDIR PCL4C (4) Copy all the files from your backup copy of the distribution disk to your work directory. For example, to copy from the A: drive to your work directory, we type: CD PCL4C COPY A:*.* (5) [OPTIONAL] Delete the makefiles that you won't need. For example, if you use the Microsoft C compiler, then you want to keep all makefiles ending *._M_ but can delete those for Turbo C (*._T_), Quick C (*._Q_), and MIX Power C (*.PRJ). You may also delete any libraries that you won't need. (6) Compile SIMPLE.C and link with the appropriate PCL4C library (PCL4C_S.LIB for all but Power C which must use PCL4C_S.MIX). Makefiles (or project files) are provided for each of the supported compilers. a) Microsoft C/C++: Type "MAKE SIMPLE._M_" b) Microsoft Quick C: Type "MAKE SIMPLE._Q_" c) Borland C/C++: Type "MAKE -fSIMPLE._B_" d) Turbo C/C++: Type "MAKE -fSIMPLE._T_" e) MIX Power C: Type "PC/E SIMPLE.PRJ" SIMPLE.C should compile without any problems as all example code has been tested with each of the supported compilers. (7) The recommended way to test SIMPLE is to run it on two computers connected by a null modem cable. Whatever is typed on one computer should be displayed on the other. SIMPLE can also be tested by connecting your port to a modem. Transmitting a "AT" to the modem should result in an "OK" being received. PCL4C Users Manual Page 6 2.0 Library Organization The PCL4C library is organized into six categories of functions. Refer to the PCL Reference Manual (PCL4C.REF) for details on individual functions. 2.1 Configuration There are three functions in the configuration category. SioPorts sets the number of PC and DigiBoard (or BOCA board) ports. SioUART is used to change the UART base address for a communications port to a non-standard address, while SioIRQ is used to assign a nonstandard IRQ line to a port. (See chapter 6, Serial Communications for more details on standard UART addresses and IRQ lines). The configuration functions SioPorts, SioUART and SioIRQ must be called before calling any other library functions. Be very careful in using these functions. Remember that your serial hardware must support the UART and IRQ that you specify. Always test any new configuration immediately. SioPorts - Sets number of PC and DigiBoard (or BOCA board) ports. SioUART | Sets the UART base address. SioIRQ - Assigns an IRQ line to a port. THE IRQ GOLDEN RULE: You may open (via SioReset) only one port per IRQ (except for the DigiBoard and BOCA board). 2.2 Initialization & Termination There are eight functions in the initialization and termination category. Together, SioParms, SioFIFO, SioRxBuf, SioTxBuf, and SioReset initialize your serial communications system. Your application must call SioRxBuf and SioTxBuf before calling SioReset, and SioReset must be called before any serial I/O processing can be done. After initialization, SioParms and SioBaud can be called to change the communications parameters without resetting the serial port. SioFlow can be called to enable hardware flow control. SioFIFO can be called to set the interrupt level for the 16550 FIFO. Before exiting from your application, SioDone must be called. Failure to call SioDone can crash your system later. SioRxBuf : Sets up receive buffer. SioTxBuf : Sets up transmitter buffer. SioFIFO : Sets the interrupt level for the INS16550. SioParms : Sets parity, stop bits, and word length. SioReset : Initialize a serial port for processing. SioDone : Terminates further serial processing. SioBaud : Sets the baud rate of the selected port. SioFlow : Enables / disables hardware flow control. PCL4C Users Manual Page 7 2.3 Modem Control & Status There are nine functions in the modem control and status category which provide your application with complete control over the status and control bits of your modem. There are two modem control bits, "Data Terminal Ready" (DTR) and "Request To Send" (RTS). These bits can be read, set, or cleared by SioDTR and SioRTS. There are four modem status bits, "Data Set Ready" (DSR), "Clear To Send" (CTS), "Ring Indicator" (RI), and "Data Carrier Detect" (DCD). SioModem can read any of the modem status bits. SioDSR, SioCTS, SioRI, and SioDCD can only read their respective modem status bit. SioGetDiv reads the baud rate divisor register so the baud rate can be determined. Refer to the chapter entitled "RS232 Signals" for a discussion of each of the control and status bits. SioDTR : Set, clear, or read the Data Terminal Ready (DTR) bit. SioRTS : Sets, clears, or reads the Request to Send (RTS) line. SioModem : Reads the modem status register. SioDSR : Reads the Data Set Ready (DSR) modem status bit. SioCTS : Reads the Clear to Send (CTS) modem status bit SioDCD : Reads the Data Carrier Detect (DCD) modem status bit. SioRI : Reads the Ring Indicator (RI) modem status bit. SioRead : Reads the contents of the 7 UART registers. SioGetDiv : Reads the baud rate divisor registers. 2.4 Serial I/O There are eleven library functions in the serial I/O category. Together, these functions give the programmer complete control over serial I/O. Higher level functions such as protocols and smart modem communications can be completely implemented in terms of these functions. Refer to the example code. SioGetc, SioGets, SioPutc, and SioPuts perform all the actual serial I/O. SioUnGetc "ungets" the last serial byte read. SioRxClear clears the receive queue while SioTxClear clears the transmit queue. SioTxFlush flushes the transmit queue. SioLine can be used to test for UART errors. SioRxQue returns the number of bytes in the receive queue while SioTxQue returns the number of bytes in the transmit queue. SioGetc : Reads the next character from the serial line. SioGets : Reads a buffer of characters from the serial line. SioLine : Reads the line status register. SioPutc : Transmit a character over a serial line. SioPuts : Transmit a buffer of characters over a serial line. SioRxClear : Clears the receive buffer. SioRxQue : Returns the number of characters in the RX queue. SioTxClear : Clears the transmit buffer. SioTxFlush : Flushes the transmit buffer by restarting transmitter interrupts. SioTxQue : Returns the number of characters in the TX queue. SioUnGetc : "Un:gets" (puts back) a specified character. PCL4C Users Manual Page 8 2.5 Error Detection There are four functions in the error detection category. They are concerned with detecting or reporting communications errors. Use of these functions can make your application significantly more robust. SioBrkKey can be used as an "emergency" exit from your application. SioBrkSig can read or modify the UART break bit. This is useful for signalling the remote system that a fatal condition has occurred. SioLoopBack can be used to test the integrity of your UART. SioError displays a error message corresponding to an error code returned from a PCL4C function (every PCL4C function returns a code). SioBrkKey : Returns non-zero if the Control-BREAK key was pressed SioBrkSig : Asserts, cancels, or detects the RS232 BREAK signal. SioError : Displays error in text. SioLoopBack : Performs a UART loopback test. 2.6 General Support There are three functions in the general support category. They are as follows: SioInfo : Returns library information such as version number. SioDelay : Delays one or more tics (18.2 tics per second). SioTimer : Returns the number of system clock tics. PCL4C Users Manual Page 9 3.0 Library Organization 3.1 Memory Models Because of the segmented architecture of the INTEL CPU, there are four memory organizations possible for computer programs. These are named the SMALL, COMPACT, MEDIUM, and LARGE memory models, which correspond to the four combinations of "near" and "far" addresses for code and data. Each executable is composed of one or more segments, where each segment can occupy from one byte to 64 KB of memory. A "near" address is a 16 bit offset in a segment, whereas a "far" address consists of both a 16 bit segment value and a 16 bit offset. In the small memory model, code and data each occupy one segment. Thus, near addresses are allocated for both code and data. In the compact memory model, code occupies one segment while data may occupy multiple segments. Near addresses are allocated for code but far addresses are allocated for data. In the medium memory model, data occupies one segment while code may occupy multiple segments. Near addresses are allocated for data but far addresses are allocated for code. In the large memory model, data and code each occupy multiple segments. Far addesses are allocated for both code and data. Thus, both code and data can use as many segments as required. Refer to your compiler manual for a discussion of the memory models supported by your compiler. PCL4C is organized as four separate libraries (PCL4C_S.LIB, PCL4C_C.LIB, PCL4C_M.LIB and PCL4C_L.LIB) corresponding to the four standard memory models. For the MIX Power C compiler, the small, medium, and large models are provided. Lastly, there is the "protected mode" model which is linked into protected mode applications such as those created by the Borland PowerPack. MODEL CODE DATA Library Small Near Near PCL4C_S.LIB & PCL4C_S.MIX Compact Near Far PCL4C_C.LIB Medium Far Near PCL4C_M.LIB & PCL4C_M.MIX Large Far Far PCL4C_L.LIB & PCL4C_L.MIX Protected Far Far PCL4C_P.LIB [PM only]. However, one can always use the large memory model library PCL4C_L.LIB with any memory model application code by explicitly declaring the PCL4C procedures to be FAR (by prefixing "far" before the name of each function in the PCL4C.H file) and declaring your receive buffer to be FAR. If you are compiling with the HUGE memory mode, link with PCL4C_L.LIB. PCL4C Users Manual Page 10 3.2 Protected Mode Protected mode programming takes advantage of the segmented architecture of 286 and up Intel processors. In contrast to normal real mode programming which limits programs to an address space of 1 MB (1024 KB), protected mode allows up to 16 MB on 286 machines and 4 GB (4096 MB) on 386 and up machines. Protected mode also offers some measure of protection of one program from another. A program that can excecute in protected mode under DOS requires three modules: (1) A DPMI (DOS Protected Mode Interface) driver loaded in memory. (2) A protected mode runtime C library linked to your program. (3) A runtime module which provides protected mode equivalents of: a) A subset of DOS interrupt 21H calls. b) A subset of BIOS calls. c) Additional functions such as protected mode memory management. The Personal Communications Library (PCL4C_P.LIB) supports protected mode. The application program must be compiled with a C/C++ compiler that supports protected mode. The Borland PowerPack for DOS provides all the required modules, although the library can be used by any DOS extender that provides the three required components as outlined above. Examine the example program PMSIMPL.C, which is a protected mode version of the normal DOS based SIMPLE.C. Compare it to SIMPLE.C to see the differences necessary to run in protected mode. In particular, note the manner in which memory is allocated for use in PCL. The transmit and receive buffers must be allocated in conventional DOS memory (the first 1MB) since serial interrupts can occur during both protected mode and real mode. long hRxMem; int RxSelector = 0; /* setup 128 byte receive buffer */ hRxMem = (long) GlobalDosAlloc( 128L ); if(hRxMem) {/* get selector & lock page */ RxSelector = LOWORD(hRxMem); GlobalPageLock(RxSelector); } else {/* fails */ ... } SioRxBuf(Port,RxSelector,Size128); Also notice that memory should be free after calling SioDone but before exiting: /* clean up PCL & free memory */ SioDone(Port) GlobalPageUnlock(RxSelector); GlobalDosFree(RxSelector); PCL4C Users Manual Page 11 3.2 Protected Mode (continued) The makefile (PMSIMPLE._B_) used to compile PMSIMPLE.C using the Borland compiler and PowerPack for DOS is as follows: ------------------------------------------------------------------------------- # # Borland C makefile for PMSIMPLE.C (protected mode) # .c.obj: bcc -ml -c -WX $< pmsimple.exe: pmsimple.obj use_dpmi.obj pcl4c_p.lib tlink -Txe c0x pmsimple use_dpmi,pmsimple,,dpmi16 emux mathwl cwl pcl4c_p.lib msimple.obj: pmsimple.c pcl4c.h use_dpmi.obj: use_dpmi.asm use_dpmi.h masm /MX use_dpmi.asm; ------------------------------------------------------------------------------- The files USE_DPMI.ASM and USE_DPMI.OBJ are provided along with the PCL4C_P.LIB library. The program SELFTEST.C can also be compiled for protected mode by using the makefile PM_SELF._B_. For more information on protected mode, refer to your DOS extender such as the Borland Power Pack. PCL4C Users Manual Page 12 3.3 Compilers Supported At this time, five C compilers are supported by PCL4C. (1) Microsoft (Optimizing) C Compiler. (2) Quick C Compiler. (3) Turbo C Compiler. (4) Borland C Compiler. (5) MIX Power C Compiler The Microsoft Optimizing C Compiler supports all memory models. Just be careful to link with the PCL4C library that corresponds to the memory model used. Recall that the small memory model is the default. Examine the (small model) makefiles *._M_ for the Microsoft compiler. The Microsoft Quick C Compiler supports all memory models, but be careful to link with the PCL4C library that corresponds with the memory model used. Recall that the small memory model is the default for the command line compiler (QCL) while the medium memory model is the default for the interactive compiler environment. Examine the (small model) makefiles *._Q_ for the Microsoft Quick C compiler. The Borland and Turbo C Compilers also support all memory models. Be sure to link with the correct PCL4C library corresponding to the memory model used. Examine the (small model) makefiles *._T_ for the Turbo C compiler. The MIX Power C Compiler supports the small, medium, and large memory models. However, older versions of Power C only support the small model. Examine the (small model) project batch files *.PRJ for the Power C Compiler. Other compilers may also work with one or more of the PCL4C libraries but have not been tested. Since registered users have the source code to the library, it should not be difficult to modify PCL4C for use with any MSDOS C compiler. Give us a call if you have any difficulty. 3.4 Using the Library The PCL4C has been tested on a Tandy 1000 (4.77 MHZ 8088 IBM PC clone), a Tandy 3000 (80286 IBM AT clone), a Tandy 1400LT (IBM XT clone), a Gateway 2000 386 (25 MHZ 80386-DX), and a Gateway 2000 486 (66MHZ 80486-DX). PCL4C has also been tested under MSDOS 2.11, 3.2, 3.3, 4.01, 5.0, 6.0 and 6.2. Please examine the PCL4C.H file. Note that COM1 is defined as port zero, not port one. The user must assume the responsibilty for passing the correct information when calling PCL4C functions. If there are any conflicts between PCL4C definitions and those in other libraries, the PCL4C definitions can be changed in the PCL4C.H file and any file that uses the definition. There is no change necessary for the library code itself. The PCL4C libraries contain no references to any runtime libraries. Only BIOS and MSDOS functions are called. PCL4C Users Manual Page 13 3.5 Application Notes 3.5.1 Terminal Programs The "terminal program" is the most common class of communications program. It is used to call up a BBS or on-line service such as CompuServe, America On-Line, etc. Refer to the programs SIMPLE and LOGIN in section 7 for examples of simple terminal programs. A more sophisticated terminal program featuring ASCII, XMODEM, YMODEM, and ZMODEM protocol file transfers can be found in our sister product -- The Personal Protocol Libray (PPL4C). Source code is included in the shareware distribution for everything except ZMODEM and the script intepreter. 3.5.2 Door Programs In order to write a door program which "takes over" a serial port without resetting the port or changing the baud rate, call SioReset with NORESET as the second argument rather than the baud rate. Call SioGetDiv to get the baud rate divisor if the baud rate must be determined. Be sure to call SioDone before returning to the invoking program. Refer to the SPAWN.C and DOOR.C example programs. Also be sure to free any memory that you may have allocated in your door program before exiting. 3.5.3 BBS Programs If you are designing a BBS program (also known as HOST programs), consider using 16550 UARTS. You should also choose a multiport card such as the DigiBoard or BOCA board if you wish to run more than 4 ports simultaneously. If you are using an error correcting modem, then you should be sure to set flow control and fix your baud rate at the highest possible transfer rates. For 14,400 modems, this means 19200 or 38400. You may need a 16550 UART in order to run at the higher speed. If you are using an older multi-speed modem (say 1200, 2400, 4800, 9600) that doesn't use flow control, you should change your baud rate to match the CONNECT message baud rate. PCL4C Users Manual Page 14 3.6 Compiling and Linking Registered users may wish to assemble PCL4C.ASM. Use the /MX switch in order to disable automatic conversion from lower case to upper case. If the /MX switch is not used, then all PCL4C function references in C code must be in upper case. To assemble using the Microsoft assembler: Model Command Small MASM PCL4C /DSMALL_MODEL /MX; Compact MASM PCL4C /DCOMPACT_MODEL /MX; Medium MASM PCL4C /DMEDIUM_MODEL /MX; Large MASM PCL4C /DLARGE_MODEL /MX; To disable transmitter interrupts, add "/DNO_TBE" to each MASM command line above. For example, to make the (small) model PCL4C.OBJ into a library file: DEL PCL4C_S.LIB LIB PCL4C_S.LIB+PCL4C,PCL4C.MAP; If you are using the MIX Power C Compiler, create the MIX object file (you will need version 1.3 of MIX which has the /_ switch): MIX /_ PCL4C_S Similarly with the other memory model libaries. See the batch files MAKE_S.BAT, MAKE_C.BAT, MAKE_M.BAT, and MAKE_L.BAT. Similiarly for MAKE_ST.BAT, MAKE_CT.BAT, MAKE_MT.BAT, and MAKE_LT.BAT. To compile and link (small model) using Microsoft C: CL /AS SIMPLE.C /LINK PCL4C_S.LIB To compile and link (small model) using Microsoft Quick C: QCL /AS SIMPLE.C /LINK PCL4C_S.LIB To compile and link (small model) using Borland C: BCC -ms SIMPLE.C PCL4C_S.LIB To compile and link (small model) using Turbo C: TCC -ms SIMPLE.C PCL4C_S.LIB To compile and link (small model) using Power C: PC /ms SIMPLE.C PCL SIMPLE PCL4C_S.MIX Makefiles or project files are provided for all example code. Borland makefiles end with the extension '._B_', Turbo C makefiles with '._T_', Microsoft C makefiles end with '._M_', Microsoft Quick C makefiles files end with '._Q_', and Power C project batch files end with '.PRJ'. The PCL4C libraries may also be used with integrated development environments. Place all required files along with the library corresponding to the memory model being used into the project file. Be sure to select the appropriate memory model, and turn off case sensitivity. PCL4C Users Manual Page 15 4.0 Talking to Your Modem A modem is used to extend the distance over which you may communicate. Without a modem, your RS232 cable is limited to a maximum of approximately 50 feet. But with a modem, you can communicate literally around the world. Also refer to Section 4.3 for details on MODEM_IO functions. These functions faciliate communications with modems. 4.1 Modem Standards Two modems can communicate over a telephone line only if they are both using the same signaling frequencies and modulation, which are determined by the the modem standards used. Modem standards can be divided into three sets: (1) speed, (2) data compression used, and (3) error control. The Bell standards (103 & 212A) are those of AT&T. The CCITT (The International Consultative Committee for Telephone and Telegraph) standards are designated as "V. ". Speed Bell 103 : 300 baud Bell 212A : 1200 baud V.21 : 300 baud V.22bis : 1200 & 2400 baud V.32 : 4800 & 9600 baud V.32bis : 4800, 7200, 9600, 12000, and 14400 baud V.34 : through 28800 baud Data Compression MNP 5 : Microcom Networking Protocol (proprietary). V.42bis : International data compression standard. Error Control MNP 2,3,4 : Three level error correction (public domain). V.42 : International error correction standard. Most of the newer high speed modems use several of the above standards. However, not all combinations of modem makes communicate easily with each other, especially at high speeds (9600 and up). PCL4C Users Manual Page 16 4.2 Flow Control With modems using data compression, the modem to modem connection will run at various speeds depending on the quality of the line. The computer to modem connection will be at a fixed baud rate. Therefore, a protocol (flow control) is necessary to synchronize the data flow between a modem and the computer to which it is connected. Refer to your modem manual for information on flow control protocols supported by your modem. Two flow control protocols are used by modems which require flow control. Software flow control is called "XON/XOFF" and hardware flow control is called "RTS/CTS". Most modems which require flow control enable hardware flow control by default. 4.2.1 Software Flow Control (XON/XOFF) In XON/XOFF (software) flow control, the computer suspends transmitting data if it receives a XOFF character (13 hex) from the modem, and continues transmitting when it receives a XON character (11 hex). Similiarly, the computer can signal the modem not to send any more data by transmitting a XOFF to it, and can tell the modem to continue transmission be sending a XON. Software flow control cannot be used to transfer binary data since binary data may have hex 11 or hex 13 bytes embedded in it. The ASCII protocol typically uses XON/XOFF to control display flow while the modem may be using RTS/CTS. XON/XOFF is implemented in the module XONOFF.C. 4.2.2 Hardware Flow Control (RTS/CTS) In RTS/CTS (hardware) flow control, the RTS line is used by the computer to signal the modem , while the CTS line is used by the modem to signal the computer. The RTS line is set OFF by the computer to tell the modem to suspend transmission, and set to ON to tell the modem to continue transmission. The CTS line is set to OFF by the modem to tell the computer to stop transmitting, and set to ON to tell the computer to continue transmitting. Given the choice, always choose hardware flow control over software flow control so that all data transmission is transparent. If hardware flow control is not the default (which it almost always is), you should modify your modem initialization string to turn hardware flow control on. Hardware flow control is internal to the PCL4C library and is selected by the SioFlow function. 4.3 MODEM_IO Functions The file MODEM_IO.C contains several functions that ease communicating with your modem. Look in the LOGIN.C code for examples of their use. Registered users can also see examples in the script interpreter SI.C. ModemSendTo : Sends string (including control chars) to the modem. ModemWaitFor : Waits for a string from the modem, passing all else through. ModemQuiet : Waits for continuous quiet of specified duration. ModemHangup : Hangs up the modem. ModemCmdState : Goes into the modem's command state. ModemEcho : Echos all serial incoming bytes to the display. PCL4C Users Manual Page 17 4.4 Modem Initialization If your application uses a modem (as opposed to using a null modem cable), then you should always send an initialization string to your modem if it is a programmable modem such as those made by Hayes. Communication programs such as PROCOMM and TELIX always send such a string automatically as soon as they start up. The particular initialization string depends on the make of your modem. Virtually all modems implement the basic Hayes AT command set, and add their own "extended" AT commands. These extended AT commands vary among modem manufacturers. For AT command set modems the following string (followed by a carriage return) may work: AT E1 S7=60 S11=60 V1 X1 Q0 S0=0 Refer to your Modem User's Guide for a full discussion of these commands. A brief description is as follows: AT : Modem attention command. E1 : Modem will echo what you send to it. S7=60 : Wait 60 seconds for carrier and/or dial tone. S11=60 : Use 60 milliseconds for tone dialing duration & spacing. V1 : Display result code as words (not numbers). X1 : Use the extended result message (CONNECT XXXX) set. Q0 : Modem returns result codes. S0=0 : Do not answer RING. If your application will answer incoming calls, then set the S0 register to the ring on which to automatically answer. Alternatively, use the ATA command to explicitly answer the modem after detecting the RING. If you send the above codes by using SioPutc (as opposed to typing them from the keyboard), then follow these guidelines: (1) Send an initial carriage return before the initialization string. (2) Pause at least two tics (18 tics to the second) after each character sent as your modem needs the time to perform its own internal processing. Pause a little longer if your modem is not accepting your initialization string. (3) Pause one and a half seconds after sending any initialization command such as ATZ or AT&F since your modem must do quite a bit of processing. If you experience any problems in initializing your modem, you should first reset it to factory settings by sending: AT&F Your modem may require more initialization than presented above. Refer to your modem manual for details. If you have a communications program such as ProComm or Telix that is known to initialize your modem correctly, then you may wish to use the same initialization string. Refer to the LOGIN.C program (and functions ModemSendTo and ModemWaitFor in the file MODEM_IO.C) for an example of sending an initialization string to a modem. PCL4C Users Manual Page 18 5.0 Problems Before developing your application, you should run the example programs. They should all execute correctly. If you have two ports on your computer, connect them together with a null modem cable and run SELFTEST.C. If SELFTEST does not execute properly then there is something wrong with either (1) your serial port hardware, (2) your null modem cable, or (3) you selected ports that are not connected by the null modem cable. Another easy test is to connect the serial port to a modem, and use SIMPLE to send a "AT" to the modem, which should respond with a "OK". If you cannot get your application to run properly, first compile and run the terminal emulator program SIMPLE provided on your distribution disk. If your application does not run but the example programs run correctly, then you have most likely made a programming mistake in your application. MarshallSoft Computing cannot debug your application, especially over the telephone! However, consider each of the following when searching for an error in your application. 1. Have you included the file PCL4C.H in your application ? 2. Did you link with the correct PCL4C library ? This is the most probable cause if your application 'hangs' as soon as it starts and you must reboot. The function SioInfo('M') returns the model ID under which the library was assembled. 3. Is your receive buffer large enough ? If you are using 1K data blocks in YMODEM, then your receive buffer should be at least 1K (2K if baud rates above 19200 are to be used). 4. Have you selected too high a baud rate (if you are using a slow PC) ? If only one COM port is being run, you should be able to run at 38400 baud on 8088 machines and 115200 on most 286 and all 386 and 486 machines. 5. Are you attempting to run another application in the background ? Try running without any other programs running in the background (unload all TSR programs). 6. If you are running two COM ports simultaneously, are you using separate receive and transmit buffers ? (you should). 7. Did SioReset return a zero value ? If not, then you must call SioReset again. See SIMPLE.C for an example. 8. Did you send the proper initialization string to your modem ? Did you set DTR and RTS ? (you should). 9. Do you have more than one COM1 port, etc. For example, if you have a COM1 port on your motherboard, you cannot add another COM1 port or modem board that uses COM1 without first disabling the COM1 on the motherboard. 10. Are you passing the proper segment of the receive (and transmit) buffer? See SIMPLE.C for an example. PCL4C Users Manual Page 19 6.0 Serial Communications 6.1 Communications Basics The heart of serial communications is the UART (Universal Asynchronous Receiver Transmitter). The IBM PC/XT/AT and compatibles use the INS8250, INS16450, or the INS16550 UART. The purpose of the UART is: (1) To convert bytes from the CPU (Central Processing Unit), into a serial format by adding the necessary start, stop, and parity bits to each byte before transmission, and to then transmit each bit at the correct baud rate. (2) To convert the incoming stream (at a specified baud rate) of serial bits into bytes by removing the start, stop, and parity bits before being made available to the CPU. The UART is part of the serial interface circuitry which allows the CPU to send and receive signals over the RS232 lines. This can be diagrammed as follows: Serial Interface +-------------------+ | | +-----+ Data Bus | +------+ | RS232 Signals | CPU +------------+ | UART | +----------------* +-----+ | +------+ | | | +-------------------+ The INS8250/16450/16550 UART is capable of operating in one of two modes, "polled" and "interrupt driven". The serial communications functions in the BIOS uses the polled method. In this approach, the CPU is typically in a loop asking the UART over and over again if it has a byte ready. If it does, the polling code returns the byte. But, if the next byte comes in before the polling code is executing again, then that byte is lost. In the interrupt driven approach, when a byte is received by the UART, an interrupt is generated and the "Interrupt Service Routine" (ISR) is executed immediately, suspending temporarily whatever else is executing. The ISR then moves the byte to the receive buffer so that your application program can later read it. When a byte is to be transmitted, it is moved to the transmit queue and transmitter interrupts are "kickstarted", which causes an interrupt to be generated each time the transmitter buffer becomes empty. The ISR is invoked, which removes the byte from the transmitter queue and writes it to the UART transmit buffer. Refer to section 6.5 "Transmitter Interrupts", section 6.6 "RS232 Signals", and section 6.7 "National INS8250, INS16450 and INS16550 UARTs" for further information on these topics. PCL4C Users Manual Page 20 6.2 Standard Port Addresses There are a few things to know about how serial communications ports are used by IBM PC/XT/AT and compatible computers. The standard IBM PC/XT/AT configuration values are as follows: Port Reg. IRQ Vector COM1 3F8H 4 12 COM2 2F8H 3 11 COM3 3E8H 4 12 COM4 2E8H 3 11 (Refer to your DigiBoard manual for DigiBoard addresses, or your BOCA board manual for BOCA port addresses). PCL4C assumes the above values. If necessary, the UART base address can be changed by SioUART, and IRQ lines can be re-assigned by SioIRQ. Remember that each port to be used concurrently must have a unique IRQ line. Refer to the PCL4C Reference Manual for specific details. When installing new communications cards, the following guidelines are recommended: (1) Be sure to read the documentation for the hardware you are installing. Pay special attention to UART base addresses and IRQ lines, particularly if trying to set up a non-standard configuration. (2) If you have a choice in base addresses and IRQ lines, always choose standard values as defined above. (3) The first port should be COM1, the second COM2, etc. Do not skip over any port number if possible. (4) Use SioUART to zero all unused ports (for example, call SioUART(COM4,0) if there is no COM4 port installed). (5) Be carefull not to configure two ports for the same address. This is easier to do than you may believe. (6) Choose an external modem over an internal one. It is much easier to debug problems with an external modem than an internal one. (7) Select hardware flow control (RTS/CTS) if flow control is required and hardware flow control is not the default. (8) Always test your port as soon as it is installed. Try several programs that use the communications ports. (9) If your serial card has two or more ports, run SELFTEST after configuring it for your new card. PCL4C Users Manual Page 21 6.3 Running 3 or 4 Ports Concurrently PCL4C supports up to 4 serial ports running concurrently (more if you have a DigiBoard or BOCA board). One free interrupt for each port is required. Refer to the next section if you have a DigiBoard or BOCA board. Interrupts IRQ4 and IRQ3 are dedicated to the communications ports in a standard IBM PC/XT/AT configuration. IRQ4 is shared between COM1 and COM3 while IRQ3 is shared between COM2 and COM4. This means that you can run two ports simultaneously provided that they don't share an interrupt. Suppose that you wish to run 3 ports simultaneously. To begin, you must have 3 UARTs (serial ports) installed on your computer. Assume, for purposes of this discussion, that COM1 is installed on your motherboard, and that you have purchased a new 2 port serial communications board. You should be able to configure the first serial board port as COM2, which uses IRQ3. Refer to the manual that came with your serial board. In order to run the third serial port concurrently with the first two, an unused interrupt must be found. If your serial card can use only IRQ3 and IRQ4, then there is no way to run a third line since IRQ4 and IRQ3 are used for COM1 and COM2. However, many serial cards can use other IRQs, typically IRQ2 through IRQ7. Many of the newer serial cards can use IRQs through IRQ15. Since IRQ5 is normally used for a second printer port, it is a good candidate for COM3. To use IRQ5 for the third serial port, first set your serial card to use IRQ5 for COM3 (refer to your serial card manual) and then add the following line to your applications code before calling SioReset: SioIRQ(COM3,IRQ5); Don't forget to disable any device that might use IRQ5, such as a second printer port or a music card. Unfortunately, there is no easy way to determine that you have no conflicts until you actually attempt to use the IRQ. If there are conflicts, your system will probably hang and you will have to reboot. To run a fourth serial port, another free IRQ must be found. On some systems, IRQ7 can be used. To use IRQ7 for the fourth serial port, first set your serial card to use IRQ7 for COM4 and then add: SioIRQ(COM4,IRQ7); Also note that conflicts are possible with port addresses. You cannot have two cards using the same port address. This problem most often occurs when adding a multiport board since each UART uses 8 consecutive port addresses. Of course, you can select any IRQ and UART address that your serial card can generate. Just be carefull about IRQ and port address conflicts. To summarize, your serial card must be able to generate the correct IRQ, which is not already being used. Refer to the entry for the SioIRQ function in the PCL4C Reference Manual. PCL4C Users Manual Page 22 6.4 Using Multiport Cards The PCL4C library supports the dumb Digiboard (PC/4 & PC/8) and the dumb BOCA board (BB1004, BB1008, and BB2016). 6.4.1 The DigiBoard PCL4C supports the DigiBoard PC/4 and PC/8. In order to use the DigiBoard, you must configure PCL4C using the SioPorts, SioUART, and SioIRQ functions. Your PC's ports must be partitioned into "standard" PC ports and dumb card ports. Remember that standard PC ports cannot share IRQs like the DigiBoard (or BOCA board) can. If you are using IRQ4 and IRQ3 for standard PC ports COM1 and COM2, then you cannot use either for DigiBoard ports (try IRQ5 or IRQ7). Suppose that COM1 through COM2 are standard PC ports (using IRQ4 and IRQ3) and you have installed a PC/8 DigiBoard that you wish to use for COM3 through COM10 using interrupt line IRQ5. You choose to use the recommended DigiBoard UART addresses starting at 0x100: ------------------------------------------------------------------------------- SioPorts(10,COM3,0x140,DIGIBOARD);/* COM3 = 1st DigiBoard port */ Address = 0x100; /* 1st DigiBoard UART address */ for(Port=COM3;Port<=COM10;Port++) /* look at each port */ {SioUART(Port,Address); /* set the UART address */ Address += 8; /* compute next address */ SioIRQ(Port,IRQ5); /* set the DigiBoard IRQ */ } ------------------------------------------------------------------------------- The DigiBoard uses 0x140 for the status address for odd interrupts and 0x141 for even interrupts [the status address is set on the board itself]. Digiboard may be contacted at 6400 Flying Cloud Drive, Eden Prairie, MN 55344. Telephone 612-943-9020 or FAX 612-943-5398. 6.4.2 The BOCA Board PCL4C supports the dumb BOCA board. As with the DigiBoard, you must configure PCL4C before using the BOCA board. For example, to configure the BOCA BB2016 to use COM1 to COM16, with base addresses starting at 0x100 and IRQ5: ------------------------------------------------------------------------------- SioPorts(16,COM1,0x107,BOCABOARD);/* COM3 = 1st BOCA board port */ Address = 0x100; /* 1st BOCA UART address */ for(Port=COM1;Port<=COM16;Port++) /* look at each port */ {SioUART(Port,Address); /* set the UART address */ Address += 8; /* compute next address */ SioIRQ(Port,IRQ15); /* set the BOCA IRQ */ } ------------------------------------------------------------------------------- BOCA may be contacted at BOCA Research, Inc., 6413 Congress Avenue, Suite 130, Boca Raton, FL 33487. Phone 407-241-8088, FAX 407-997-0918. PCL4C Users Manual Page 23 6.5 Transmitter Interrupts PCL4C comes assembled for all memory models with transmitter interrupts enabled. PCL4C can also be assembled without transmitter interrupts enabled by including "/DNO_TBE" on the MASM line. When transmitter interrupts are NOT enabled, the following logic occurs everytime SioPutc or SioPuts is called: 1. Wait for the UART transmit buffer to become empty. The UART transmit buffer may not be empty if the previous transmit is not completed (the UART breaks down the byte & sends 1 bit at a time). 2. When the UART transmit buffer is empty, the byte from the SioPutc or SioPuts call is loaded into the UART transmit buffer and control is returned to the caller. Note that you can not write to the UART any faster than the UART baud rate. Transmitter interrupts provide a way for your application program to write to the serial port faster than the baud rate, but transmitter interrupts do have several caveats. To begin, they are slower than polled transmission, although not significantly. Secondly, they are more complex and thus result in a slightly larger library. The increased complexity of transmitter interrupts is due to the fact that even though transmitter interrupts are enabled, a transmitter interrupt can occur only when the UART transmitter register transitions from not-empty to empty (a byte has just been transmitted). To start the transmitter interrupt process, the first byte in the PCL4C transmitter queue must be transmitted by SioPutc (or SioPuts) rather than by the Interrupt Service Routine (ISR). The remainder of the bytes in the PCL4C transmit queue are transmitted by the ISR when the transmitter interrupt occurs. This process is called "kickstarting" the transmitter interrupts. When transmitter interrupts are enabled, the following logic occurs everytime SioPutc or SioPuts is called: 1. The byte from SioPutc or bytes from SioPuts are put into the PCL4C transmitter queue. 2. If there is no byte presently being transmitted, then the transmitter interrupt process is kickstarted. 3. Each time a transmitter interrupt occurs, the ISR gains control, removes the next byte from the PCL4C transmitter queue and puts it in the UART transmit register. While you can now call SioPutc and SioPuts faster than the baud rate, bytes are still transmitted at the given baud rate. The advantage of using transmitter interrupts is that an application program can write a string of bytes to the serial transmit queue without having to wait for those bytes to be transmitted before regaining control. When running a streaming protocol (one that doesn't wait for any acknowledgement from the other side), be sure to check for transmitter buffer overflow (eg, SioPutc returns -1). PCL4C Users Manual Page 24 6.6 RS-232 Signals RS-232 is the name of the serial data interface standard used to connect computers to modems. Most IBM compatible computers are built with at least one serial port and use either DB9 (9 pin) or DB25 (25 pin) connectors. A summary of these pins and their function follows. For more detailed information, refer to one of the many books dealing with RS-232 interfacing. Signal Ground Pin 7 (DB25), Pin 5 (DB9) The SG line is used as the common signal ground, and must always be connected. Transmit Data Pin 2 (DB25), Pin 3 (DB9) The TX line is used to carry data from the computer to the modem. Receive Data Pin 3 (DB25), Pin 2 (DB9) The RX line is used to carry data from the modem to the computer. Data Terminal Ready Pin 20 (DB25), Pin 4 (DB9) The DTR line is used by the computer to signal the modem that it is ready. DTR should be set high when talking to a modem. Data Set Ready Pin 6 (DB25), Pin 6 (DB9) The DSR line is used by the modem to signal the computer that it is ready. Request to Send Pin 4 (DB25), Pin 7 (DB9) The RTS line is used to "turn the line around" in half duplex modems, and for hardware flow control in most modems that require flow control. Clear to Send Pin 5 (DB25), Pin 8 (DB9) The CTS line is used to "turn the line around" in half duplex modems, and for hardware flow control in most modems that require flow control. Data Carrier Detect Pin 8 (DB25), Pin 1 (DB9) The DCD line is used by the modem to signal the computer that a data carrier signal is present. Ring Indicator Pin 22 (DB25), Pin 9 (DB9) The RI line is asserted when a 'ring' occurs. PCL4C Users Manual Page 25 6.7 National INS8250, INS16450, and INS16550 UARTs The Personal Communications Library is based on the standard National INS8250, INS16450, and INS16550 UARTs. The 8250 was the original UART used in the IBM PC, whereas the 16450 is a faster version found on most 286 & up machines. The 16550 contains a 16 byte FIFO to further reduce communications overhead. These UARTs consists of 8 register ports as follows: Offset R/W Register 0 R/W Receiver (read) / Transmitter (write) 1 R/W Interrupt Enable (read) 2 R Interrupt Identification 2 W FIFO control (INS16550 only) 3 R/W Data Format (Line Control) 4 R/W RS-232 (Modem) Control 5 R/W Line Status 6 R/W RS-232 (Modem) Status 7 R/W Not used. For the standard PC ports (not DigiBoard or BOCA ports), the UART registers are based at 3F8h (COM1), 2F8h (COM2), 3E8h (COM3), and 2E8h (COM4). COM1 and COM3 share interrupt request line IRQ4 while COM2 and COM4 share request line IRQ3. This means that COM1 and COM3 can't be used concurrently. Similarly for COM2 and COM4. If you have a DigiBoard (or BOCA board) installed, you will have 4 or more additional ports using INS16450 or INS16550 UARTS. The default DigiBoard and BOCA board ports are located at 100h, 108h, 110h, etc. Refer to your DigiBoard (or BOCA board) manual. Four sources of interrupts are possible with the 8250 and 16550: (1) receiver error or BREAK, (2) receiver data ready, (3) ready to transmit, and (4) RS232 input. These four sources of interrupts are summarized as follows: Source of Interrupt Action Required to Clear Receiver error or BREAK. Read Line Status register. Receiver data. Read data from data register. Transmitter Buffer Empty. Write to data register or read IID reg. RS232 input. Read Modem Status register. However, PCL4C only enables transmitter and receiver interrupts. If you are not familiar with the INS8250, several good books are available. Refer to the Serial Communications chapter for recommendations. Although a knowledge of the 8250 is not necessary to use PCL4C, a general knowledge of the theory of asynchronous serial communications is recommended. PCL4C Users Manual Page 26 6.8 Register Summary REG 0 : Data Register Reading from the data register fetches the next input byte, once it is ready. Writing to the data register transmits the byte written to it over the serial line. REG 1 : Interrupt Enable The Interrupt Enable register enables each of four types of interrupts when the appropriate bit is set to a one. bit 3 : Enable interrupt on RS232 input. bit 2 : Enable interrupt on receiver error or break. bit 1 : Enable interrupt on transmitter buffer empty (TBE). bit 0 : Enable interrupt on received data (RxRDY). REG 2 : Interrupt Identification (IID) Reading the Interrupt Identification (read only) register once an interrupt has occurred identifies the interrupt as follows: Bit 2 Bit 1 Bit 0 Priority Interrupt 0 0 1 none none 1 1 0 0 (high) Serialization or break. 1 0 0 1 Received data. 0 1 0 2 Transmitter Buffer Empty. 0 0 0 3 (low) RS232 Input. In the INS16650, REG 2 (write only) is also the FIFO control register. Writing bits 6 & 7 will set the FIFO trigger level (number of bytes received before an interrupt is generated). Bit 7 Bit 6 Trigger Bit 7 Bit 6 Trigger 0 0 1 byte 1 0 8 bytes 0 1 4 bytes 1 1 14 bytes REG 3 : Line Control RS232 line parameters are selected by writing to this register. bit 7 : DLAB = 0 bit 6 : BREAK on(1), off(0). bits 5-3 : Parity None(000),ODD(001),EVEN(011),MARK(101),SPACE(111) bit 2 : One stop bit(0), two stop bits(1). bits 1-0 : Data bits = 5 (00), 6(01), 7(10), 8(11). When the Divisor Latch Access Bit (DLAB) is 1, registers 0 and 1 become the LS and MS bytes of the Baud Rate Divisor registers. Baud Divisor Baud Divisor Baud Divisor 300 0180 4800 0018 38400 0003 1200 0060 9600 000C 57600 0002 2400 0030 19200 0006 115200 0001 PCL4C Users Manual Page 27 REG 4 : Modem Control RTS, DTR, loopback testing, and General Purpose Outputs #1 and #2 are controlled by the Modem Control register as follows: bit 4 : Enable local loopback. bit 3 : Enable GP02. Necessary for 8250 interrupts. bit 2 : Enable GP01. bit 1 : Set / clear RTS. bit 0 : Set / clear DTR. REG 5 : Line Status Reading the Line Status register provides status information as follows (1 for TRUE, 0 for FALSE) : bit 6 : Transmitter Empty. bit 5 : Transmitter Buffer Empty (TBE). bit 4 : BREAK detect. bit 3 : Framing error. bit 2 : Parity error. bit 1 : Overrun error. bit 0 : Data Ready. REG 6 : Modem Status Reading the Modem Status register provides the following status information (1 for TRUE, 0 for FALSE) : bit 7 : DCD status. bit 6 : RI status. bit 5 : DSR status. bit 4 : CTS status. bit 3 : Delta DCD status. bit 2 : Delta RI status. bit 1 : Delta DSR status. bit 0 : Delta CTS status. The delta bits (bits 0 through 3) are set whenever one of the status bits (bits 4 through 7) changes (from 0 to 1 or from 1 to 0) since the last time that the Modem Status register was read. Reading the Modem Status register clear the delta bits. REG 7 : Scratch Register There is no function associated with register 7. It does not exist in early versions of the 8250. PCL4C Users Manual Page 28 7.0 Example Programs Six example programs are include with PCL4C. In addition, the Personal Protocol Library for C (PPL4C) includes the terminal program TERM which features ASCII, XMODEM, YMODEM, and ZMODEM protocol transfers. Complete source code is included in the shareware product for all of the protocols above except ZMODEM. In order to get ZMODEM source, PPL4C must be registered. 7.1 MINIMAL MINIMAL is the simpliest possible communications program. It displays on the screen what it reads from the serial port and transmits over the serial line what is typed at the keyboard. COM1 and 9600 baud are hard coded for simplicity. 7.2 SIMPLE SIMPLE is a simple terminal program. It operates like MINIMAL, except that both a port and a baud rate can be specified. For example. SIMPLE 1 9600 7.3 LOGIN LOGIN is programmed to dial our support BBS (205-880-9748) and log on as GUEST. Start LOGIN like SIMPLE by providing a COM port and a baud rate. For example, LOGIN 1 38400 7.4 SPAWN and DOOR The SPAWN program is the same as the SIMPLE program except that it spawns DOOR when the user types a '$'. For example, to start SPAWN on COM3, type SPAWN 3 The DOOR program is also the same as SIMPLE except that it can "take over" a serial port without changing any of the port parameter. Exiting DOOR returns to the invoking program (SPAWN). 7.5 SELFTEST The SELFTEST.C program is designed to test serial ports provided that two ports are avaiable which can be connected together with a null modem cable. SELFTEST can also be used to test your multiport board. For example, to test PC port COM1 against COM2, type: SELFTEST PC 1 2 SELFTEST may need to be configured for non-standard PC ports or your multiport board. Refer to the SELFTEST source code for more information. PCL4C Users Manual Page 29 8.0 Legal Issues 8.1 Registration If you wish to register the PCL4C library, please send $75 plus $5 S&H ($10 outside of North America) to: MarshallSoft Computing, Inc. Post Office Box 4543 Huntsville AL 35815 Multiple copies are available: $55 for 3 to 9, $45 for 10 to 19, and $35 for 20 or more. A site license is also available for $675 (includes 20 sets of printed documentation). We pay shipping. We accept American Express, MasterCard, and VISA (account number, expiration date, exact name on your card, and complete card billing address required), checks in US dollars drawn on a US bank, purchase orders (POs) from recognized US schools and companies listed in Dun & Bradstreet, and COD (street address and phone number required) within the USA (plus an additional $3 COD charge). You can also order PCL4C from The Public Software Library (PSL) in Houston Texas with your American Express, MasterCard, VISA, or Discover card by calling 800-242-4PSL (from overseas: 713-524-6394) or by FAX at 713-524-6398 or by CompuServe at [71355,470]. THESE NUMBERS ARE FOR ORDERING ONLY. The product number for PCL4C is 10908. Please have your credit card billing address ready. If you wish to update from an older version of PCL4C, send $20 plus $5 S&H ($10 outside of North America). Updates must be ordered directly from MarshallSoft Computing. The registered package includes: o Small,Compact,Medium,Large & PM libs w/o shareware screens. o Assembler source code for the library. o Laser printed Users and Reference Manuals. o Telephone, FAX, and BBS support for one year. Print the file INVOICE.DOC if an invoice is needed. The registered user will receive the latest version of PCL4C shipped by two day priority mail (packet airmail overseas). A 3.5" diskette is provided unless a 5.25" diskette is requested. PCL4C Users Manual Page 30 8.2 License MarshallSoft Computing, Inc. grants the registered user of PCL4C the right to use one copy of the PCL4C library (in object form) on a single computer in the development of any software product (other than libraries such as PCL4C). The user may not use the library on more than one computer at the same time. The source code for the library (PCL4C.ASM) is copyrighted by MarshallSoft Computing and may not be released in whole or in part. Products developed using PCL4C can include the object form of the library and may be distributed without any royalty. 8.3 Warranty MARSHALLSOFT COMPUTING, INC. DISCLAIMS ALL WARRANTIES RELATING TO THIS SOFTWARE, WHETHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, AND ALL SUCH WARRANTIES ARE EXPRESSLY AND SPECIFICALLY DISCLAIMED. NEITHER MARSHALLSOFT COMPUTING, INC. NOR ANYONE ELSE WHO HAS BEEN INVOLVED IN THE CREATION, PRODUCTION, OR DELIVERY OF THIS SOFTWARE SHALL BE LIABLE FOR ANY INDIRECT, CONSEQUENTIAL, OR INCIDENTAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE SUCH SOFTWARE EVEN IF MARSHALLSOFT COMPUTING, INC. HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES OR CLAIMS. IN NO EVENT SHALL MARSHALLSOFT COMPUTING, INC.'S LIABILITY FOR ANY SUCH DAMAGES EVER EXCEED THE PRICE PAID FOR THE LICENSE TO USE THE SOFTWARE, REGARDLESS OF THE FORM OF THE CLAIM. THE PERSON USING THE SOFTWARE BEARS ALL RISK AS TO THE QUALITY AND PERFORMANCE OF THE SOFTWARE. Some states do not allow the exclusion of the limit of liability for consequential or incidental damages, so the above limitation may not apply to you. This agreement shall be governed by the laws of the State of Alabama and shall inure to the benefit of Marshallsoft Computing, Inc. and any successors, administrators, heirs and assigns. Any action or proceeding brought by either party against the other arising out of or related to this agreement shall be brought only in a STATE or FEDERAL COURT of competent jurisdiction located in Madison County, Alabama. The parties hereby consent to in personam jurisdiction of said courts. PCL4C Users Manual Page 31 9.0 Summary 9.1 Revision History Version 1.0 - 14 January 1991 - original release. Version 1.1 - 11 March 1991 o Added SioUnGetc function to library. Version 1.2 - 1 June 1991 o SioParms bug - could not call before SioReset. o SioReset bug - was not saving & restoring all regs. Version 1.3 - 1 July 1991 o Added NORESET option to SioReset. o Added SioDSR, SioCTS, SioDCD, SioLoopBack, and SioRI. Version 2.0 - 1 Nov 1991 o Reorganized as four memory model libraries. o Added SioModel function to library. o Added support for Quick C and Power C. Version 2.1 - 1 Dec 1991 o Fixed bug due to Microsoft Assembler (MASM 5.0,5.1) error. NOTE: MarshallSoft incorporated as "MarshallSoft Computing, Inc." on December 23rd, 1991. Version 3.0 - 15 Jan 1992 o Added SioUART function. o Added "UART undefined" error code. o Added "Bad or missing UART" error code. o Added "Port already enabled" error code. o Added "Cannot enable both COM1 & COM3 ..." error code. o Fixed several minor bugs (using new automated testing). Version 3.1 - 1 March 1992 o Added SioFIFO (INS16550 support). o Added SioIRQ function. o Increased maximum receive buffer size to 32K bytes. Version 3.2 - 1 May 1992 o Modified SioReset so that it no longer clears DTR & RTS. o Modified SioModel & renamed to SioInfo. o Fixed bug in SioDone when using 2 ports simultaneously. o Added SioFlow to library. o Added YMODEM-G protocol to TERM program. PCL4C Users Manual Page 32 9.1 Revision History (continued) Version 3.3 - 3 August 1992 o Fixed bug in SioUnGet when using 2 ports simultaneously. o Add SioRead function. Version 3.4 - 4 Jan 1993 o Library modified to use up to four ports simultaneously. o SioIRQ was modified to include a third argument. o EXAMPORT utility distributed to registered users. Version 3.5 - 15 May 1993 o Supports dumb DigiBoards ( PC/4 and PC/8). o Two new error traps added ("No such IRQ" & "No such ISR"). o ASCII file transfer protocol added to TERM (with XON/XOFF). Version 4.0 - 18 Oct 1993 o The library supports transmitter interrupts. o Corrects bug in Ver 3.5 requiring calling SioIRQ for COM3/4. o All example code compiles with supported C++ compilers. o The SioIRQ function has been simplified. Version 4.1 - 1 May 1994 o Transmitter FIFO enabled. o Minor internal modifications. o Supports dumb BOCA boards (BB1004, BB1008, & BB2016). o Port definition extented to COM16. Version 4.2 - 1 Sept 1994 o A flow control bug was fixed. o SioGetDiv function added. o SioRxBuf & SioTxBuf function modified. Version 4.3 - 15 March 1995 o BREAK detection bug fixed, o Port definitions extended to COM20. o Support for IRQ8 through IRQ15. o Line status bits preserved. (The TERM program moved to PPL4C) Version 5.0 - 20 November 1995 o Supports Protected Mode o Renamed SioRxFlush to SioRxClear. o Renamed SioTxFlush to SioTxClear. o Added SioTxFlush o Added more choices in SioInfo. o Removed SioCrtWrite (use putch instead). o Removed SioKeyPress (use kbhit instead). o Removed SioKeyRead (use getch instead). o Added SioGets. o Added SioPuts. PCL4C Users Manual Page 33 9.2 Function Summary Refer to the PCL4C Reference Manual (PCL4C.REF) for detailed information on the communications and support functions. A one line summary of each function follows: SioBaud Sets the baud rate of the selected port. SioBrkKey Returns non-zero if the Control-BREAK key was pressed. SioBrkSig Asserts, cancels, or detects BREAK signal. SioCTS Reads the Clear to Send (CTS) modem status bit. SioDCD Reads the Data Carrier Detect (DCD) modem status bit. SioDelay Delays one or more tics (18 tics per second). SioDone Terminates further serial processing. SioDSR Reads the Data Set Ready (DSR) modem status bit. SioDTR Set, clear, or read the Data Terminal Ready (DTR) bit. SioError Displays error in text. SioFIFO Sets the interrupt level for the INS16550. SioFlow Enables / disables hardware flow control. SioGetc Reads the next character from the serial line. SioGets Reads a buffer of characters from the serial line. SioGetDiv Reads the baud rate divisor registers. SioInfo Returns library information (version number, etc.) SioIRQ Assigns an IRQ line to a port. SioLine Reads the line status register. SioLoopBack Performs a UART loopback test. SioModem Reads the modem status register. SioParms Sets parity, stop bits, and word length. SioPorts Sets # ports, 1st DigiBoard / BOCA port & status reg. SioPutc Transmits a character over a serial line. SioPuts Transmits a buffer of characters over a serial line. SioRead Reads any of 7 UART ports. SioReset Initialize a serial port for processing. SioRI Reads the Ring Indicator (RI) modem status bit. SioRTS Sets, clears, or reads the Request to Send (RTS) line. SioRxClear Clears the receive buffer. SioRxBuf Sets up receive buffer. SioRxQue Returns the number of characters in the receive queue. SioTimer Returns the number of system clock tics. SioTxBuf Sets up transmit buffer. SioTxClear Clears the transmit buffer. SioTxFlush Restarts transmitter interrupts thus flushing the TX queue. SioTxQue Returns the number of characters in the transmit queue. SioUART Sets the UART base address. SioUnGetc "Un-gets" (puts back) a specified character. 9.3 Further Reading The best way to learn about serial communications is to read a good book on the subject. Several good texts are available. Two that I like are: (1) C Programmers's Guide to Serial Communications by Joe Campbell (SAMS) (2) Mastering Serial Communications by Peter Gofton (SYBEX). PCL4C Users Manual Page 34 10.0 Other MarshallSoft Computing Products 10.1 The Personal Protocol Library for C/C++ The Personal Protocol Library for C (PPL4C) consists of a C/C++ language library which implements XMODEM, XMODEM-CRC, XMODEM-1K, XMODEM-G, YMODEM, YMODEM-G, and ZMODEM file transfer protocols. A script compiler and interpreter is also included which is capable of such tasks as automatically logging onto a BBS and downloading a file or retrieving mail. Three example script programs are included. The protocol library (PPL4C) requires the Personal Communications Library for C (PCL4C). The Personal Protocol Library for C is available for $40 plus $3 S&H ($6 S&H overseas). 10.2 The EMS Expanded Memory Library The EMS4C library implements version 3.2 of the LIM (Lotus-Intel-Microsoft) specification for expanded memory. It will run with either version 3.2 or 4.0 of the LIM specification. The EMM4C library (included with the EMS4C library) is an expanded memory manager which allows C programmers to allocate and free EMS (expanded) memory similiar to malloc and free in the standard C runtime library. Both EMM4C and EMS4C require that your system be configured with expanded (EMS) memory. But, 386 & up systems can use extended memory as expanded memory. The EMS Expanded Memory Library for C is available for $35 plus $3 S&H ($6 S&H overseas). PCL4C Users Manual Page 35