Messages in this thread | | | Date | Mon, 17 Jan 2000 15:07:35 +0100 | From | Jens Benecke <> | Subject | Serial Port voltage drops with Linux |
| |
Hi,
we have a home-made device connected to the serial port which we are trying to program with Linux. I have posted here already and got a lot of useful answers, BitWizard (thanks) even translated a QBasic source which was supposed to do what we needed for our project into C for Linux.
Thanks to all who answered!
But now we have a somewhat different problem.
The situation is this: When we connect the hardware to the serial port, the signal amplitude breaks down to lower than +3V (which is miniumum for the PC to detect a "0"). With DOS, the signal amplitude varies from -10..+10 V (approx) for 1/0 signals. With Linux, it's -10..<+3V, and that is not enough.
I tried not starting setserial when starting Linux, this did not change. When gpm was started, the serial port status changed though - although the mouse is on ttyS0 and our hardware on ttyS1.
The next thing for us will probably be dosemu....
Yes, I know this project is ridiculous. I didn't invent it. And nobody wanted to learn MS Visual C++ & Co, we'd all be happy getting this to run under Linux.
Do you have any further ideas about this? Why do the ports behave so much differently (no matter if we start setserial or not) when using Linux? In theory (yeah, right) it's hardware that should behave the same under any OS, at least in respect to voltage levels and power consumption?
We'd all really appreciate if you can give us any further insights (or RTFMs...) you might have on this.
BTW, we tried three different serial port hardware boards (ISA) so the hardware should not be at fault.
I have put the QBasic source and the C source at http://www.pinguin.conetix.de/serial.zip, perhaps someone can shed a little light on this. There is also a complete DOS floppy boot image including QBasic and the .bas file for those who do not have a bootable DOS handy (dos.img.gz).
Thanks a lot!
-- _ciao, Jens_______________________________ http://www.pinguin.conetix.de · "[Microsoft] ... guarantees 99.8% NT uptime for certain hard-/software. That's exactly the 3 minutes daily that my NT server needs to reboot." -- ZDnet editorial
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/
| |