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densimitre
Joined: 21 Dec 2004
Posts: 45
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| 16F877A USART Problem |
 Posted: Tue Nov 15, 2005 9:26 am |
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Hi friends.
I am having troubles with mi PIC 16F877A and his USART module. I am usign MAX232.
This code donīt work.
| Code: |
#include <16F877A.h>
#device adc=10
#FUSES NOWDT, HS, NOPUT, NOPROTECT, NODEBUG
#FUSES BROWNOUT, NOLVP, NOCPD, NOWRT
#use delay(clock=20000000,RESTART_WDT)
#use rs232 (baud=57600,parity=n,[b]xmit=PIN_C6,rcv=PIN_C7[/b],bits=8,restart_wdt) // HARDWARE USART
void main() {
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
while(1)
{
int i=0;
while(i<255) {
printf("Current CHAR: %C\n\r",i);
i++;
delay_ms(100);
}
}
}
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But following code works.
| Code: |
#include <16F877A.h>
#device adc=10
#FUSES NOWDT, HS, NOPUT, NOPROTECT, NODEBUG
#FUSES BROWNOUT, NOLVP, NOCPD, NOWRT
#use delay(clock=20000000,RESTART_WDT)
#use rs232 (baud=57600,parity=n,[b]xmit=PIN_C4,rcv=PIN_C5[/b],bits=8,restart_wdt) // SOFTWARE USART
void main() {
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
while(1)
{
int i=0;
while(i<255) {
printf("Current CHAR: %C\n\r",i);
i++;
delay_ms(100);
}
}
}
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itīs seems hardware usart fail.
thank you. |
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asmallri
Joined: 12 Aug 2004
Posts: 1634
Location: Perth, Australia
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| Posted: Tue Nov 15, 2005 9:42 am |
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try using the same IO pins as the hardware UART but forcing the compiler to use software.
| Code: | | #use rs232 (baud=57600,parity=n,xmit=PIN_C6,rcv=PIN_C7,bits=8, force_sw) // SOFTWARE USART |
For your hardware implementation you forgot to add the keyword errors but this affects the receive logic not the trnsmit logic.
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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densimitre
Joined: 21 Dec 2004
Posts: 45
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| Posted: Tue Nov 15, 2005 12:49 pm |
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| asmallri wrote: | try using the same IO pins as the hardware UART but forcing the compiler to use software.
| Code: | | #use rs232 (baud=57600,parity=n,xmit=PIN_C6,rcv=PIN_C7,bits=8, force_sw) // SOFTWARE USART |
For your hardware implementation you forgot to add the keyword errors but this affects the receive logic not the trnsmit logic. |
HI
thankz for answer..
Well, My intention is to send information towards the PC only....i will try your suggestion.
Bye |
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densimitre
Joined: 21 Dec 2004
Posts: 45
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| Posted: Wed Nov 16, 2005 6:57 am |
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| asmallri wrote: | try using the same IO pins as the hardware UART but forcing the compiler to use software.
| Code: | | #use rs232 (baud=57600,parity=n,xmit=PIN_C6,rcv=PIN_C7,bits=8, force_sw) // SOFTWARE USART |
For your hardware implementation you forgot to add the keyword errors but this affects the receive logic not the trnsmit logic. |
Hi there
I have tested your code, and this is the result.
1.- USARTīs pins with force_sw as simple I/O, works fine for rs232 communications. TX and RX functions works very well.
2.- I did some test.
a.- TX in force_sw mode / RX in hardware mode ==> TX ok / RX not OK
b.- TX in hardware mode / RX in force_sw mode ==> TX not OK / RX OK
| Code: |
#use delay(clock=4000000)
#use rs232(baud=9600,bits=8,parity=n,xmit=pin_c6,rcv=pin_c7,force_sw,errors,stream=pc1)
#use rs232(baud=9600,bits=8,parity=n,xmit=pin_c6,rcv=pin_c7,errors,stream=pc2)
void main() {
char c;
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_psp(PSP_DISABLED);
setup_spi(FALSE);
setup_timer_0(RTCC_INTERNAL|RTCC_DIV_1);
setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);
setup_comparator(NC_NC_NC_NC);
setup_vref(FALSE);
while (1) {
c=fgetc(pc2); //RX in hardware mode
fputc(c,pc1); //TX in force_sw mode
}
}
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after
| Code: |
while (1) {
c=fgetc(pc2); //RX in hardware mode. DONT WORK
fputc(c,pc1); //TX in force_sw mode
delay_ms(1000);
fputc(c,pc2); //As RX dont work, TX in HARD/SW mode dont work also.
}
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Im afraid USART HARDWARE ist FAULT....
A question:
- When i use usart in force_sw mode, the data to send is stored in RAM or TXSTA register????
thank you |
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Ttlemah
Guest
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| Posted: Wed Nov 16, 2005 10:19 am |
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What compiler version?.
If you look back a few days, another poster was having problems with the receive, on the hardware UART, on another chip, and I suggested he simply set the TRIS bit for the RX line. This is a fault, that seems to have appeared a few compiler versions ago, with some chips, when using standard_io, where the compiler clears the TRIS bit incorrectly, setting the receive pin as an output (I have reported it to CCS). Can I suggest you try the same fix?
The software UART does everything in RAM.
Best Wishes |
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