tomg@code3.com (Tom Green) (06/19/91)
To: ron@eatdust Subject: Re: Help: how to output to a port such as a RS232? Newsgroups: comp.lang.c In-Reply-To: <1991Jun14.152321.1698@cherokee.uswest.com> References: <1991Jun11.135431.22955@udecc.engr.udayton.edu> <8380@awdprime.UUCP> Organization: 3M Health Information Systems Cc: Bcc: In article <1991Jun14.152321.1698@cherokee.uswest.com> you write: >In article <8380@awdprime.UUCP> sjb@piobe.austin.ibm.com writes: >>In article <1991Jun11.135431.22955@udecc.engr.udayton.edu>, Jinghong Li writes: >>> Help needed: would someone tell me how to send output >>> to a port such as a RS232? Any sepcial commands? > >other stuff deleted. > >I responded to him by mail, but thought I'd post because I'm also interested >in communications. I got a book by Sam's, called "C programmer's Guide to >Serial Communications" by Joe Campbell, ISBN 0-672-22584-0. > >I haven't implemented any code with it yet, but while reading it I feel it's >quite comprehensive and informative. > >Have others read it? Comments? Do you recommend other books over (or in >conjunction with) to understand (and be able to write code for) async comm? I found the book to be quite good. A few problems with the book are that the definitions for the odd and even parity masks for the U8250 were incorrect. The book should read: #define ODD_MASK 0x20 #define EVEN_MASK 0x30 The other problem is that the book doesn't define the base address for serial ports 3 and 4. These can be added with the definition of: #define COMM3 0x3e8 #define COMM4 0x2e8 Also the definition of the comm base address to be a unsigned char pointer I found to be inappropriate to deal with regardless of the explanation given in the book. Just declare it as an unsigned int. Otherwise the book is an excellent base for a good library of routines and I recommend it. All standard disclaimers apply. -- Tom Green - Life's a pain, then you die. _/_ __ ____ __ "I shall be swift, and merciful" - the Gorn / /_// / //_/ tomg@code3.code3.com _/