henry@ginger.sri.com (Henry Pasternack) (07/31/90)
This is technically a UNIX question, but I have this paranoid feeling that posting to a UNIX bulletin board would be an exercise in futility. Perhaps someone over here can help me out. Problem: My 68000 board is running now, and I'm successfully programming it in C using the Sun3 compiler. I've written a two-part communications program for the purpose of downloading S-record code from a SPARCStation to the 68000. I use kermit to provide terminal emulation over the Sun's 'ttya' port. The 'ttyb' port is driven by my communications program which listens for file requests from the client and dumps S-records on command. I'm having a lot of trouble getting the interface to '/dev/ttyb' to work. I admit to knowing virtually nothing about UNIX I/O, and the reference manuals aren't much help. The port already seems to be configured for 9600 baud, which is convenient. I do an 'fopen' on '/dev/ttyb' and use 'gets' and 'fprintf' to perform I/O. The Sun has no problem receiving command lines from the client, but when the client begins polling for a response after sending a request, it gets a garbled copy of its request back. It seems as though the buffer UNIX is creating is bidirectional, rather than dual-unidirectional. Can anyone give me an understandable explanation of how to set up my SPARCStation to do simple and effective I/O to the serial ports? Thanks. -Henry
stevem@sauron.Columbia.NCR.COM (Steve McClure) (07/31/90)
In article <14703@unix.SRI.COM> henry@ginger.sri.com (Henry Pasternack) writes:
+
+ This is technically a UNIX question, but I have this paranoid
+feeling that posting to a UNIX bulletin board would be an exercise
+in futility. Perhaps someone over here can help me out.
+
+ Problem: My 68000 board is running now, and I'm successfully
+programming it in C using the Sun3 compiler. I've written a two-part
+communications program for the purpose of downloading S-record code
+from a SPARCStation to the 68000. I use kermit to provide terminal
+emulation over the Sun's 'ttya' port. The 'ttyb' port is driven by
+my communications program which listens for file requests from the
+client and dumps S-records on command.
+
+ I'm having a lot of trouble getting the interface to '/dev/ttyb'
+to work. I admit to knowing virtually nothing about UNIX I/O, and
+the reference manuals aren't much help. The port already seems to be
+configured for 9600 baud, which is convenient. I do an 'fopen' on
+'/dev/ttyb' and use 'gets' and 'fprintf' to perform I/O. The Sun
+has no problem receiving command lines from the client, but when the
+client begins polling for a response after sending a request, it gets
+a garbled copy of its request back. It seems as though the buffer
+UNIX is creating is bidirectional, rather than dual-unidirectional.
+
+ Can anyone give me an understandable explanation of how to set
+up my SPARCStation to do simple and effective I/O to the serial ports?
+
I wrote some PROM Programmer software for a Unix box and ended up opening
a read-only file and a write-open file on the same port. This same technique
is used in the Unix cu command so I assume it is pretty much standard. Hope
this helps.
--
----------------------------------------------------------------------
Steve email: Steve.McClure@Columbia.NCR.COM 803-791-7054
The above are my opinions, which NCR doesn't really care about anyway!
CAUSER's Amiga BBS! | 803-796-3127 | 8pm-8am 8n1 | 300/1200/2400mason@Unify.Com (Mark Mason) (08/02/90)
In article <2254@sauron.Columbia.NCR.COM> stevem@sauron.UUCP (Steve McClure) writes: >In article <14703@unix.SRI.COM> henry@ginger.sri.com (Henry Pasternack) writes: [del...] >+ I'm having a lot of trouble getting the interface to '/dev/ttyb' >+to work. I admit to knowing virtually nothing about UNIX I/O, and >+the reference manuals aren't much help. The port already seems to be >+configured for 9600 baud, which is convenient. I do an 'fopen' on >+'/dev/ttyb' and use 'gets' and 'fprintf' to perform I/O. The Sun >+has no problem receiving command lines from the client, but when the >+client begins polling for a response after sending a request, it gets >+a garbled copy of its request back. It seems as though the buffer >+UNIX is creating is bidirectional, rather than dual-unidirectional. >+ >+ Can anyone give me an understandable explanation of how to set >+up my SPARCStation to do simple and effective I/O to the serial ports? >+ [del...] you need to do a fflush() on the stream before "changing direction" (reading -> writing or writing -> reading). like: fgets() --> fflush() fprintf() --> fflush() fgets() etc. Hope this helps. mason pyramid!unify!mason for 1 more week... mason@reed.bitnet forever! -- {{ucdavis,csun,lll-crg}!csusac,pyramid,sequent}!unify!mason -or- mason@reed.bitnet The above opinions/falsehoods/misconceptions are my own....