Matrix user forums

Hi folks, I have attached the flowchart I have done for a darkness detector.

Everything seems to be working fine except for when I want the LED (connectd to GP5)to come on for 1 second. For som reason it it comes on for about half a second which is too quick. I've set the internal clock to 8Mhz and 4Mhz for the delays and have checked my chip configurations. For the life of me I just cannot figure out where I have gone wrong so would appreciate somebody pointing it out.

Thanks for your time.............JDR04

Hi John,
The only thing I can spot is osccon value not matching clock frequency.
osccon=0x60; = 4MHz (since this is the default value on switch on then osccon is not required).
osccon=0x70; = 8MHz

Martin

Hi Martin, thanks for your time. Could I clear one thing up as I think I may misunderstand it.

I've got osccon=70 so I can run the chip at 8Mhz. The 4 Mhz I set was for the delay periods? Am I confusing something here????

Thanks a lot.....John

Hi John,

JDR04 wrote:'ve got osccon=70 so I can run the chip at 8Mhz. The 4 Mhz I set was for the delay periods? Am I confusing something here????

Yes, I'm afraid you are.
The Clock speed must be set to match the actual osc speed.
All the dalays are automatically calculated.

So if osccon = 0x70; sets osc to 8MHz then you must also set clock speed to 8MHz.
Same if you have a 20MHz crystal then you must also set clock speed to 20MHz.
Etc..

Martin

OK, finally get it.

Thanks for your patience.............Take care,John

No problem at all John.
Glad you have got it now.

Martin