UART test program in C for 16F873

Hardware
The testboard K3 is set up with reset circuit, crystal oscillator at 4 MHz and a MAX232 for RS232 communication. The 4 arrows in the circuit diagram indicate signal direction.

Software in C

//************************************************************************
// Processor: PIC16F873 at 4 MHz
// Function: Characters received via RS232 (19200 baud 8-N-1) are returned
// Hardware: Testboard K3
// Language: C
// Compiler: CCS PCM
// Filename: 873_ser.c
// Author: Lars Petersen, oz1bxm@pobox.com
//*************************************************************************

#include <16F873.h>
#fuses NOPROTECT, XT, NOWDT, PUT, NOLVP, BROWNOUT
#use delay(clock=4000000)
#use rs232(baud=19200, xmit=PIN_C6, rcv=PIN_C7 ) // Use the micro's UART

main() {
   setup_adc(ADC_OFF);  // all pins portA digital I/O
   while (TRUE) {
     putc(getc());      // echo the received char
   }
}

Remarks
The MAX232 is used for RS232 communication. A simpler circuit can be set up using DS275, see the homepage of Wichit Sirichote from Thailand.

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