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Ossyle
Joined: 03 Dec 2007
Posts: 1
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| RS232 communication problem |
 Posted: Mon Dec 03, 2007 7:01 am |
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Hi.
I am trying to RS232 communication with 16F628-04/P UART but I didn't success. I did simple practice. For example I receive RS232 data with getch() function and write porta by leds. I simulate circuit with Proteus, its work. But I didn't work on breadbord. Please help for this.
Sorry about bad english.
Circuit
Program.c
| Code: | #include "C:\Program Files\PICC\Projects\628yeni.h"
int deg;
void main()
{
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)
{
output_a(0);
deg=getc();
if(deg!="")
{
output_a(deg);
delay_ms(500);
}
}
} |
Program.h
| Code: | #include <16F628.h>
#FUSES NOWDT //No Watch Dog Timer
#FUSES INTRC_IO //Internal RC Osc, no CLKOUT
#FUSES NOPUT //No Power Up Timer
#FUSES PROTECT //Code protected from reads
#FUSES NOBROWNOUT //No brownout reset
#FUSES NOMCLR //Master Clear pin used for I/O
#FUSES NOLVP //No low voltage prgming, B3(PIC16) or B5(PIC18) used for I/O
#FUSES NOCPD //No EE protection
#use delay(clock=4000000)
#use rs232(baud=9600,parity=N,xmit=PIN_B2,rcv=PIN_B1,bits=8) |
Thanks for help. |
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SherpaDoug
Joined: 07 Sep 2003
Posts: 1640
Location: Cape Cod Mass USA
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| Posted: Mon Dec 03, 2007 11:00 am |
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You should NOT connect an RS232 signal directly to a PIC pin. The RS232 signal voltage can swing as much as +15V to -15V which can seriously damage a PIC.
The best way is to use an RS232 driver chip like the MAX232. You can learn a lot by reading the MAX232 datasheet even if you don't use that chip.
For receiving only you can probably get away with a simple 10k resistor between the RS232 connector and the PIC, especially at moderate baud rates like 9600 baud.
_________________
The search for better is endless. Instead simply find very good and get the job done. |
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Ttelmah
Guest
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| Posted: Mon Dec 03, 2007 11:11 am |
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Also, remember that unless an inverter is present, the 'invert' option is needed in the RS232 setup.
Best Wishes |
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