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Blob
Joined: 02 Jan 2006
Posts: 75
Location: Neeroeteren, Limburg, Belgium
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| Pic 18F2520 rs232 |
 Posted: Thu Apr 17, 2008 8:26 am |
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Hello to you all,
I am working on a new pic at the moment.
PIC18F2520
Now i want to communicate with this device, using RS232.
I made a USB interface with a USB<->RS232 convertor.
And a small PC program tot communicate with the Pic
I have basically the same code running on a 18F242.
here is a short testing version:
| Code: |
#include <18F2520.h>
#device ADC=10
#include <stdlib.h>
#fuses HS, NOWDT, PUT, BORV27, NOLVP, EC_IO, NOSTVREN, NODEBUG, PROTECT, MCLR //, EBTR
#org 190, 8190 {}
#use fast_io(A)
#use fast_io(B)
#use fast_io(C)
#use delay (clock=20000000)
#use rs232 (baud=19200, xmit=PIN_C6, rcv=PIN_C7)
#define LED PIN_C3 // LED
int int_a, rs_pnt;
char rs_in[10];
boolean bl_ok;
#INT_RDA
void serial_isr();
#separate
void blink_fast();
#separate
void blink_slow();
#INT_RDA
void serial_isr()
{
char a;
a = getc();
printf("ok");
bl_ok = !bl_ok;
}
#separate
void blink_fast()
{
output_high(LED);
delay_ms(5);
output_low(LED);
delay_ms(5);
}
#separate
void blink_slow()
{
output_high(LED);
delay_ms(25);
output_low(LED);
delay_ms(25);
}
#separate
void main(void)
{
int_a = 0;
bl_ok = 0;
rs_pnt = 0;
set_tris_c(129);
SETUP_ADC_PORTS(NO_ANALOGS);
output_low(LED);
enable_interrupts(GLOBAL);
enable_interrupts(INT_RDA);
while(1)
{
if(bl_ok)
blink_fast();
else
blink_slow();
}
}
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On the 242 I allways get the "ok" message on my screen when i send something over.
On the 2520, nothing happens.
also, i tried in the int_rda code:
| Code: |
char a;
a = getc();
if (a == '#')
printf("ok");
bl_ok = !bl_ok;
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when i send # my LED blinking speed changes every time i send it again, so it seems the 2520 receive some data.
but whin i apply this code:
| Code: | if (a == '#')
bl_ok = !bl_ok; |
my LED speed stays the same.
Also i am not getting anything from the pic.
The pin occupation of 242 and 2520 are the same for my app.
I also tried using a stream etc at the rs232 setup.
Is there any change in the 2520 i am not aware of?
Thanks a lot!
Blob |
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Douglas Kennedy
Joined: 07 Sep 2003
Posts: 755
Location: Florida
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| Posted: Thu Apr 17, 2008 8:52 am |
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| Most would never put a printf in an isr. It may not be your problem but it will in time eventually bite you. Look at circular buffers and read this forum for this kind of issue has been asked and answered very very many times. |
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Blob
Joined: 02 Jan 2006
Posts: 75
Location: Neeroeteren, Limburg, Belgium
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| Posted: Fri Apr 18, 2008 1:00 am |
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Hello Douglas,
you are right i should have searching a bit harder.
I found the problem!
It was a wrong interpretation of the fusebits...
i did set EC_IO => external clock.
but i us a 20 MHz Xtal....
So i should only set HS, not HS and EC_IO...
I saw the problem when i was thinking my led blinks too slow for intervals of 5 or 25 ms...
Best Regards,
Blob |
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