Interrupt for software uart 18F452

[Fredrik]

How can I make a interrupt routine for the software uart that can both receive and transmit serial data? (I need to use two uart's with interrupt). If I send a character using hyperterminal, I only get back garbage. Do I loose data information because of the ext interrupt? The start message "PIC started" (Check the code below) is printed out nicely. If i poll the port in the main loop everything works fine.

Please help.

/Fredrik

//--------------------------------------------------------

#include <18f452.h>
#device *=16 ADC=10
#include <string.h>

//#FUSES HS,NOWDT,NOPROTECT,PUT,BROWNOUT
#ID CHECKSUM
#ZERO_RAM
#use DELAY(CLOCK=19860800)

#use fast_io(A)
#use fast_io(B)
#use fast_io(C)

#byte PORTA=0xf80
#byte PORTB=0xf81
#byte PORTC=0xf82
#byte PORTD=0xf83
#byte PORTE=0xf84

#int_ext
void ext_isr(void);

#use rs232(baud=38400, xmit=PIN_B1, rcv=PIN_B0, PARITY=N, BITS=8)

void main(void) {

SET_TRIS_A(0x00); // A out
SET_TRIS_B(0x01); // Input: B0, Output: B1-B7
SET_TRIS_C(0xa8); // 1010 1000
SET_TRIS_D(0x00); // D out
enable_interrupts(INT_EXT);
enable_interrupts(GLOBAL);

printf("\r\nPIC started\r\n");
delay_ms(100);

while(1)
{
}
}

#int_ext
void ext_isr(void)
{
char c;
c = getc(); // receive the character
putc(c); // echo back character to sender
}
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This message was ported from CCS's old forum
Original Post ID: 14337

[Nikki]

:=#use rs232(baud=38400, xmit=PIN_B1, rcv=PIN_B0, PARITY=N, BITS=8)

I did this, but it only worked at a maximum 57600 with a 40Mhz crystal. Try lowering the baud rate to 19200.

The main problem I think is the interrupt latency of 35 or more instruction.

Nikki
___________________________
This message was ported from CCS's old forum
Original Post ID: 14339

[Fredrik]

Added the line "ext_int_edge(H_TO_L);" to the code and that solved the problem.

:= SET_TRIS_D(0x00); // D out
:= ext_int_edge(H_TO_L);
:= enable_interrupts(INT_EXT);
:= enable_interrupts(GLOBAL);


/Fredrik
___________________________
This message was ported from CCS's old forum
Original Post ID: 14371