Messages in this thread | | | Date | Thu, 11 Nov 1999 18:24:34 +0100 | From | Jens Benecke <> | Subject | Need info about serial port programming -UPDATE |
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Hi,
a while ago I asked about accessing the serial port from Linux. I got a lot of very nice answers, thanks to anyone for answering, I will publish our results and code when the project is finished.
The "problem" now is that I have received detailed information about how the hardware "the other guys" are about to solder speaks to the serial port, which makes me kind of sick. It seems that there is no thought of a standard serial RS232 handshake protocol.
The hardware expects a clock signal on the DTR pin (whenever DTR is toggled it sends a bit), a fixed configuration signal (bit width, LSB/MSB conf, etc) on the RTS pin, and sends the binary data on the DTR port. They designed it so that "it's easy to program from DOS" (which is probably even true), but I would like the machine to run under Linux, because it has to put the gained data over a network.
The sampling frequency with which the DTR is being fed is way below a kHz, so my former ideas about 4..5kHz sampling frequency seemed to have failed on the hardware (the A/D chip is a cheap one, it seems). All we want to do with it is to long-term analyze the sound/speech volume in (i.e. useage of) a certain room here over a few weeks, the sound doesn't even have to be recognizable. (One of the things that we have been strictly forbidden to do is to use a soundcard, so don't ask. Strictly speaking, this is a 100% hardware project, the PC is thought to be only there for making the data look pretty. =)
Our time frame is extremely tight, I have to present a rough code draft on Monday, and I have no idea whether it is at all possible to access the RS232 ports directly from Linux, without digging deep into kernel programming (which I probably wouldn't manage in the time anyway). So:
- Is there a way to control those pins from user space, directly enough so that we can get the data?
- Alternatively, is there a _simple_ way (e.g. an IC) to put between the data line and the RS232 that implements a handshake so that I can use termios and so on? (Remember, the time frame is almost nonexistant.)
Thanks to all who enlighten me ;)
-- _ciao, Jens_______________________________ http://www.pinguin.conetix.de
Windows NT indeed has very low Total Cost of Ownership. Trouble is, Microsoft _owns_ Windows NT. You just licensed it.
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