Calculating and setting PIC TMR LOOP

[camerart]

Hi,
I have a PIC program using TMR0 and need to calculate and set the TIMER LOOP to be 20MS.
The clock speed is 4MHz.
Can anyone help me set it please?
Thanks,
Camerart.

 

[Ian Rogers]

Yup!!! Is this for "Ye Olde pic18f4431" per chance??

The 4mHz will give 1uS clocks... You need to count to 20,000.. presetting TMR0L and TMR0H with 0xB1DF and set T0CON with 0x88.. ( timer on.. 16 bit.. prescaler off.. ) you need to preset each interrupt..
If you only have the 8 bit timer, then you'll need the prescaler.. A prescaler of 128 and a preset of 99 will do the job..
T0CON = 0x86.. TMRO = 0x63..

 

[camerart]

Yup!!! Is this for "Ye Olde pic18f4431" per chance??

The 4mHz will give 1uS clocks... You need to count to 20,000.. presetting TMR0L and TMR0H with 0xB1DF and set T0CON with 0x88.. ( timer on.. 16 bit.. prescaler off.. ) you need to preset each interrupt..
If you only have the 8 bit timer, then you'll need the prescaler.. A prescaler of 128 and a preset of 99 will do the job..
T0CON = 0x86.. TMRO = 0x63..

Forsooth 'tis an 18LF2520. (I've got one on a test PCB, before moving to an 19LF4431)

Here's the program, with only the above T0CON and TMR0 settings, before trying your program from the other thread. (NOTE: bit 6 is '1'?? for 8BIT)

It takes a while to see both LOOPs. Cut and paste from LINE 152, into H-UART for test in Oshonsoft SIM.

Thanks, C.

 

[Ian Rogers]

19LF4431

?????

(NOTE: bit 6 is '1'?? for 8BIT)

Just can't get it quite right!! Why I help out here, lord only knows.....

I lob this into my simulator later.... I'll be back!!

 

[camerart]

?????

Just can't get it quite right!! Why I help out here, lord only knows.....

Hi I,
Because you are much needed.
C.

 

[camerart]

Hi I,
I've just realised that the program needs a radio module HC-12. to test it. I'll do that next.
I've connected 1x SERVO as a test.
C.