| Title: | Atari ST, TT, & Falcon |
| Notice: | Please read note 1.0 and its replies before posting! |
| Moderator: | FUNYET::ANDERSON |
| Created: | Mon Apr 04 1988 |
| Last Modified: | Tue May 06 1997 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 1433 |
| Total number of notes: | 10312 |
I have a problem with an application using RS232 and handshaking :
I wrote an application that sends data using the RS232-port.
A received XOFF (^S) should stop the transmission immediately.
I thought about two solutions but both bring up special problems :
1. Setting up the port hardware with XON/XOFF.
Problem : The application will continue to write into the trans-
mission buffer until its full. Then the application
is blocked until it can deliver more characters.
How can I sense the XOFF-state to prevent filling up
the buffer to enable other tasks during waittime ?
2. Let the application do the handshake.
Problem : The application serves the XOFF-command and stops
sending into the buffer. But... there may be some
characters pending in the buffer which will continue to
be sent until the buffer is empty. How can I set the
transmission buffer size to zero ?
Thanks for any hints,
Detlef.
| T.R | Title | User | Personal Name | Date | Lines |
|---|---|---|---|---|---|
| 1081.1 | Bconxxx Functions | MPGS::RADOFF | Mon Feb 25 1991 09:21 | 6 | |
If you use the Bconxxx functions set for AUX, you can intercept and
interpret incoming stream characters and control transmittion and
reception in that manner. This is a means I have used for years that
works perfectly.
Steve
| |||||
| 1081.2 | Some ways around this | PRNSYS::LOMICKAJ | Jeffrey A. Lomicka | Mon Feb 25 1991 11:48 | 20 |
Some ideas: - If you transmit with a loop that calls Bcostat() before each character, it should tell you if the port is ready for more data or not. - If you use Iorec, you can watch the input and output pointers as they go by, and even change them. Careful about synchronization with Atari's interrupt routines. I'd change them at IPL 7 if possible. - One good way would be to set the output buffer size small in Iorec, so that the O/S cannot queue up more than, say 8 characters. Then monitor incoming data for XON/XOFF, and you will never overrun the XOFF by more than 9 characters, which should be okay. - Another good way may be to only transmit if the difference between head and tail in Iorec is small, and you are not in an XOFF condition. I once write a driver (for a raw VAX, no operating system) that transmitted as long as the input buffer in the uart didn't contain a ^S. You'd be amazed how well that worked. | |||||