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eyewonder300
Joined: 09 Jun 2004 Posts: 52
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Need help getting CLKOUT to work |
Posted: Wed Jun 09, 2004 9:34 pm |
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I'm using an 'F877 and would like to get the xtal clock freq (19.2MHZ) /4 from the CLKOUT (pin 14) to use in the circuit. I have used a logic probe to look for any output from the pin, and cannot see anything, nor will it drive the desired circuit.
I have used the below program just to verify that the PIC is actually running, and it is.
Can anyone point out what I'm doing wrong? Thanks
Steve
// ns_tst.c
////////////////////////////////////////////////////////////////////////
#include <16F877.H>
#FUSES RC,NOPROTECT,NOWDT,NOPUT,NOBROWNOUT,NOLVP,NOCPD,NOWRT
#use delay(clock=10000000)
#include "nep_hdr\nep_lcd.h"
//////////////////////////////////////////////////////////////////////////
main()
{
lcd_init();
lcd_putc("Hello, World!");
delay_ms(1000);
lcd_gotoxy(3,3);
lcd_putc("Goodby, World!");
} |
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PCM programmer
Joined: 06 Sep 2003 Posts: 21708
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Posted: Wed Jun 09, 2004 10:13 pm |
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Quote: | I have used a logic probe to look for any output from the pin,
and cannot see anything, nor will it drive the desired circuit. |
The CCS compiler puts a hidden SLEEP instruction at the end of main().
Your program is executing this instruction, which causes the oscillator
to stop running. The solution is to put a constant loop at the end of
main(). See the example below:
main()
{
lcd_init();
lcd_putc("Hello, World!");
delay_ms(1000);
lcd_gotoxy(3,3);
lcd_putc("Goodby, World!");
while(1); // Add this line
} |
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eyewonder300
Joined: 09 Jun 2004 Posts: 52
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Posted: Wed Jun 09, 2004 10:36 pm |
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Thanks, PCM. That simple change made it work.
Steve |
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