18f27k40 - timer0 changes from K22, K80 series 8bit/16bit mode

[longpole001]

oh and when i first setup this original code, back some years back i refereed to this calculator, so dont use this calc for timer 0 for k40

[tumbleweed]

// T0CS FOSC/4; T0CKPS 1:64; T0ASYNC synchronised;
// TMR0H 155;
// TMR0L 0;
// T0OUTPS 1:1; T0EN enabled; T016BIT 8-bit;

For the K40 in 8-bit mode I don't see how that gets you 10ms @ 16MHz clock

Doesn't that get you 156 x 64 x 250ns = 2.496ms ?

[richard]

Doesn't that get you 156 x 64 x 250ns = 2.496ms ?

yes , my bad it needs to be T0CKPS 1:256;

accidently set fosc to 4mhz when trying to match sheldons settings trying to guess at his fosc and forgot to regenerate the code

[tumbleweed]

it needs to be T0CKPS 1:256

That'll get you a lot closer... 9.984ms

If you use the postscaler you can get 10.000ms:

- set prescaler to 1:32 T0CKPS<3:0> = 0101
- set postscaler to 1:10 T0OUTPS<3:0> = 1001
- set period count = 125 (load TMR0H with 125-1=124)
gets you 32 x 10 x 125 x 250ns = 10.000ms

For 32MHz, just change the prescaler to 1:64:
64 x 10 x 125 x 125ns = 10.000ms

[richard]

i'm impressed on just how versatile these later generation chips are. there is heaps to learn

[longpole001]

also be aware now of the errata on timer0 k40 series , T0ASYNC bit problem , when FOSC/4 clock source