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Altera_Forum's avatar
Altera_Forum
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11 years ago

Problem of receiving data from UART RS232

Hello everyone. I am now working on a project and it has to receive data from the COM port (RS232). I have written a receiver in VHDL. However, the code does not always receive correct data byte ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

What I think is the problem is:

In check_start, you test at rcount = 217 if RxD = 0. If so, you reset the counter and proceed to receiving. That is a half the bit time. Then you test in receiving at again at rcount=217 that's agiain at half a bit time, so that's around the signal transition of the RxD signal. You should wait a full rcount cycle to test again.