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Guest
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| UART message capture |
 Posted: Tue Dec 14, 2004 7:59 pm |
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Hi all,
I am using the PIC18LF452 in a project, and it's UART to talk to a 433Mhz transceiver. It needs an "AT" command, and sends back a "\r\nOK\r\n".
From what i've read in the manual, it uses a much stripped down version of the AT Hayes command set, that is used in modems.
What i want to do is read in the response, and process it to get any data other than the OK. I think i should use the interrupt RDA, and i have seen code to do that in the examples.
Sometimes a response has more than 2 pairs of "\r\n". A pair for the data, and a pair for the OK.
I need to know:
>Should i use a circular buffer, or linear? and why?
>How do i get the whole response? given that i can't rely on the "\r\n" to indicate the response, without losing the data OR "OK" to validate.
Thanks |
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Mark
Joined: 07 Sep 2003
Posts: 2838
Location: Atlanta, GA
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Guest
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| Posted: Tue Dec 14, 2004 10:07 pm |
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Hi Mark,
Thanks for the reply, i think a linear buffer should do the trick for now, i'll just make it long enough for big data bursts.
Should i wait for the 1st "\r\n" and disable the interrupt, and use fetc() until no more chars are read in? because i'll get something like "\r\nddddddddddddddd\r\nddddddddddddd\r\nOK\r\n". I don't have a particular 'start' or 'end' character to reference to.
What i mean is something like:
| Code: |
#int_RDA
RDA_isr()
{
buffer[next_in] = getc() //read the uarts 1st buffer char
increment next_in
buffer[next_in]= getc(); // read the uarts 2nd buffer char
if (buffer[next_in-1]==13)&(buffer[next_in]==10))
{
found start (possibly)
disable_interrupt(int_RDA);
do
{ // do this quickly enough to avoid RS232 errors (OERR, FERR)
buffer[next_in] = getc()
increment next_in
}while (kbhit() )
enable_interrupt(int_RDA);
//when kbhit fails= no data in RCREG, return to normal operation
//should have a buffer with data to parse
}
}
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I am only using the interrupt to gather the data so i can process it later in the program.
After it is processed, i then flush the buffer elements to theNull char '0' ready to be used again.
Q's
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>Would this be adequate? or do i have other things to check?
>After gathering the input data, should i turn off the interrupt so that the buffer isn't corrupted during processing, and re-enable for non process activities so that i can response to incomming radio messages?
Thanks so far. |
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