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> Serial Port Woes..., Just a minute of your time.
omega
post Feb 4 2005, 04:49 AM
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Hi guys.

I've been trying now for a few hours over a few days to get the serial port under pdaxrom to successfully work. It's interfacing to my microcontroller, and I have stepped it down to 3.2volts max signal... The problem is that I'm not getting the correct data......

I've tried command line stuff, but it doesn't want to work properly for me either. I can see this stuff on my windows pc in telnet without a problem.

9600 baud, 8 bits data, 1 stop bit, 1 start bit, no parity...

It also seems that I have no flow control...

anyone got any simple commands or bits of a c program i can try? I've been using a c program called com... it lets you supply information and displays the results... but they are not correct...

Hyperterminal works grand...... on the 3v interface the high is exactly 3volts and the low very close to zero so i think the levels are okay.... it's been driven for a CD4050 buffer chip which should have more than enough switching speed!
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omega
post Feb 4 2005, 04:59 AM
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Is there a terminal program for pdaxrom? Minicom doesn't want to behave for me...

I have the program written and it's graphing on gnuplot but the values are being read wrong from the serial port
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omega
post Feb 9 2005, 01:41 AM
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Anyone got any idaes - the serial port should work correctly just using the rx / signal ground lines?
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lardman
post Feb 9 2005, 03:31 AM
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rx/tx & gnd (pins 2,3 & 5 I think).

Check you've not got the rx & tx the wrong way round (sticjk a null modem cable in and see if it works then).

Minicom works for me, what troubles are you having with it?


Si
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omega
post Feb 23 2005, 05:34 AM
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Sorry lardman for not replying...

Got it working! The problem was that I made a 5v TTL to 3v level shifter. It came to me last night that the MAX232 inverts the signals... Just had to replace the 4050 buffer with a inverter and away it went.
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lardman
post Feb 23 2005, 07:34 AM
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No worries, glad you got it working.

What are you doing with the microcontroler?


Si
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omega
post Feb 23 2005, 08:25 AM
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I am building a multi channel test and measurement system. I would like to have my Z function as a basic oscilloscope... I actually had gnuplot drawing the input waveforms this morning... I will have to find time to develop it further though..
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lardman
post Feb 23 2005, 09:12 AM
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Cool. Sounds like an interesting project.

I've got a ratoc usb host card and was thinking of finding some USB DAQ hardware lying about (I work in an Engineering dept at uni) and seeing if I could get it working (I'm after temperatures mainly). I imagine usb oscilloscopes are also available.

In any case I'm going to have to look at what has driver source available.

Good luck, let us know how it goes.


Si
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craigtyson
post Feb 23 2005, 10:59 AM
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Not sure Im being mad but what about using the mic in as a scope input (up to 44KHz) its a simple 8bit? AtoD converter no? With a buffer amp on the front to stop over voltage damage you could have a single trace Digital Scope. Its a pitty the mic isnt stereo.

Craig.

Heres a link to a Windows PC version PC Scope
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