lweekes
Joined: 06 Jun 2004
Posts: 1
Location: UK
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| 18f6620 strange corrupt UART behaviour |
 Posted: Sun Jun 06, 2004 3:52 am |
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Hi,
I�m having a few problems converting code to run from a 18f258 to a 18f6620 and wondered if anyone could help.
On the 18f6620 if I use the following everything is ok:
| Code: | while (1) {
ch = fgetc(com1);
fputc(com2);
} |
However if I try the following on it I get around 80% of the message output ok, but some of the characters are corrupted:
| Code: | while (1) {
buffer[i++] = fgetc(com1);
if (ch == 13) {
fprintf(com2,�%s�, buffer);
}
} |
What I see being output varies every time, sometimes its 100% perfect but that�s about 1 in 10 (although totally random). On the 18f258 everything is ok with both methods above.
An example of this problem is if I had the ascii character 1 (0x31) being output sometimes the first half of the byte gets sent and then the second so I see two bytes 0x3 and 0x1 as individual bytes on the output, not a single transmitted character.
Am I doing something stupid? All other operations work ok on the pic it�s just the sending from a stored array that I�m having a problem with. If I exchange fprintf for putc and output character by character I still see the same random problems (I've even tried delaying each character being sent but no joy).
I�m confident the comms settings are ok on the PIC and receiving hardware, but this looks like some form of timing problem to me but I�m not sure what to investigate. I�m using a MAX202 as the transceiver for both uarts and version 3.190 of CCS. My fuses and uses are as below:
| Code: | #include <18F6620.h>
#device adc=8
#use delay(clock=10000000)
#fuses NOWDT,WDT128,HS, NOPROTECT, NOOSCSEN, NOBROWNOUT, BORV25, NOPUT, NOCPD, NOSTVREN, NODEBUG, NOWRT, NOWRTD, NOCPB, NOEBTRB, NOEBTR, NOWRTC, NOWRTB, NOLVP
#use rs232(baud=9600,parity=N,xmit=PIN_C6,rcv=PIN_C7,bits=8, stream=com1)
#use rs232(baud=9600,parity=N,xmit=PIN_G1,rcv=PIN_G2,bits=8, stream=com2) |
If anyone has any help or guidance to the source of the problem I would be really grateful as this is driving me up the wall.
Thanks,
Lee |
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Haplo
Joined: 06 Sep 2003
Posts: 659
Location: Sydney, Australia
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| Posted: Sun Jun 06, 2004 4:32 am |
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Two things to mention:
1. The format of fputc() is value = fputc(cdata, stream). You need to specify both the stream name and the data to be sent out.
2. The "%s" in the fprintf() expects a null-terminated string. Yours is not. That may be the reason for the random results you are seeing. |
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