delay_ms problems

[Guest]

I'm using the ICD-U40 to program a PIC18F4431. I'm trying to make two leds blink. The program seems to have problems with the line "delay_ms()" because the leds do not blink within the time I specified. The leds blink sporadically and stop. I think it might be my oscillator since it looks like a timing issue. I have a 40MHz oscillator with pin 1 as no connect, pin 7 connected to GND, pin 8 connected to OSC1 of the pic, and pin 14 connected to +5. Is there something wrong with my oscillator selection?

Also, what is the best way to send timed electrical pulses with delays in them accurately?

Here's the program for the blinking leds:
#include <18F4431.h>
#device ICD=TRUE
#fuses HS, NOLVP, NOWDT, NOPUT
#use delay(clock=40000000)

#define RED_LED PIN_B4
#define GREEN_LED PIN_B5

void main() {
while(TRUE){
output_low(GREEN_LED);
delay_ms (500);
output_high(GREEN_LED);
delay_ms (500);
output_low(RED_LED);
delay_ms (500);
output_high(RED_LED);
delay_ms (500);
}
}

Any suggestions or answers would help greatly and would be most appreciated. Thanks so much!!!

[sseidman]

I wasn't aware that the 4431 can clock off a 40MHz crystal. I know it can clock off a 20MHz, or a 10MHz crystal at 40MHz if you use the hardware 4X PLL multiplier. To use the PLL, clock with a 10MHz crystal, and use the H4 fuse instead of HS. You will need to reset the chip after you program it with this fuse.

Scott

[Mark]

Try it without the debugger.
Have you verified all the power and ground connections?
Do you have a pullup on the MCLR?

[PCM programmer]

[Guest]

I replaced the HS with the EC and still have the same problem as well as checking the suggestions made about disconnecting the debugger and verifying power and gnd. I still get the same results. Is it okay to use a 40MHz clock oscillator? Or should I try a 20MHz crystal? Can I buy crystal oscillators over the counter at the stores without making an online order?

Thanks for the suggestions!

[Neutone]