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hexfet13
Joined: 03 Jul 2009
Posts: 8
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| PIC18f2550 and rs232 garbage |
 Posted: Fri Jul 03, 2009 10:33 am |
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Hi, I'm trying to work with rs232 on pic18f2550 but with a simple test program in my hyperterminal I see only garbage . Originally, I need to implement a simple rs232 protocol to transfer a data stream with pll enabled (4MHz external crystal) but with pll enabled (fuses HSPLL and #use delay( clock=48000000 ) ) or not (only HS fuses enabled) the result is always the same.
Where's the mistake?
Thanks!
| Code: |
#include <18f2550.h>
#fuses HS,NOWDT,NOPROTECT,NOPUT,NOLVP,NOMCLR
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7,ERRORS )
void main()
{
printf("\f");
while(1){
delay_ms(500);
printf("testing ");
}
} |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Fri Jul 03, 2009 1:36 pm |
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1. Read the markings on the crystal. Is it really 4.000 MHz ?
2. Make sure you re-compiled the program and re-programmed it into
the PIC, after making changes.
3. Check the settings on HyperTerminal. Make sure it's set for
9600 baud, No parity, 8 bits, 1 stop bit, and No hardware or software
handshaking. Or try a different Terminal progam, such as TeraTerm:
http://www.ccsinfo.com/forum/viewtopic.php?t=39388&start=18
4. Do you have a MAX232-type chip between the PIC and the PC ?
Did you build the board and the serial cable yourself, or did you
buy them ? If you built them yourself, then check for wiring errors. |
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hexfet13
Joined: 03 Jul 2009
Posts: 8
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| Posted: Sun Jul 05, 2009 4:19 am |
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Thanks for reply.
I've solved the problem: the guilty was a spike upon Vcc caused by max3232.The amplitude of it was over 1.5V and the result was a dead pic that work at irregular intervals.
Thanks again. |
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