interrupt behaviour / compiler versions?

[avery earle]

I have the linux compiler for PIC16.
The serial echoback below functions
if compiled with ccsc version 3.112
If I use 3.249, the pic seems not to
hear me and huh?


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#include <16f877.h>
#use delay (clock=20000000)
#use rs232 (baud=9600, parity=N, xmit=PIN_C6, rcv=PIN_C7)
#fuses HS,NOWDT,NOPROTECT,NOLVP


#define ringsize 16
int ringbuffer[ringsize];
int ringR = 0;
int ringW = 0;


#int_rda
void receive()
{
// b1 drives a LED.

if (ringW & 1) output_high (pin_b1); else output_low (pin_b1);

ringbuffer[ringW] = getchar();
ringW++;
//ringW %= ringsize;
if (ringW >= ringsize) ringW = 0;
}


void main(void)
{
int j;

printf ("\r\nPower\r\n");

enable_interrupts (INT_RDA);
enable_interrupts (GLOBAL);

for (;;) {

while (ringR != ringW) {
j = ringbuffer[ringR];
ringR++;
// ringR %= ringsize;
if (ringR >= ringsize) ringR = 0;

putchar (j);
} // end while

} // end for (;;)

} // end main()


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[PCM programmer]

I compiled your program with the Windows version of PCM 3.249 and
and ran it on a PicDem2-Plus board. It worked OK. I typed keys in
a terminal window and the LED changed state on each keypress, and
it echoed back the characters. The only things I changed were the
frequency and fuse. I changed them to 4 MHz and XT, to fit my board.

You're using vs. 3.249 of the Linux version. I don't have that. I suggest
that you compile with both 3.112 and 3.249 and compare the .LST
files. There will probably be several differences in the library code
and the start-up code. Sometimes CCS changes the order of
the things they do in the start-up code. Also, at one point, they
changed from loading registers (such as ADCON1) with a byte,
to setting or clearing individual bits. These types of changes won't be
relevant to your problem. You need to find a change that's causing
the problem.