Delay question

[HenrikOlsson]

Hi Paul,
New day, fresh head...
You said:

at 4 MHz, 3 instructions on and 3 instruction off = 6 instructions per cycle, therefore f=1000000/6=166666.667 Hz (twice that noted above)

That is of course correct. I based my calculation on a 20Mhz so 5000000/6 = 833kHz which is what I stated in my post which is also correct (but not half of 166kHz).

Thanks for the 16F vs 18F explanation. I guess it would take up more code to check which bank we're in before each goto instead of just setting the correct one?

Thanks!
/Henrik Olsson.

[paul borgmeier]

Henrik,

My apologies - you are and were indeed correct (166.667 / 2 != 833.33).

I am guessing the 16F PBP compiler code is not optimized to check to see if it is in the same page as the goto. I bet it sets the PCLATH every time it encounters a goto just to be safe. I do not think it would add PIC code - I think it would take more compiler code to do this check - MELABS must not have thought it was not worth it to potentially save one instruction (100% guess by me)?

[mister_e]

I think it will use the CHK?RP macro simply for safety sake. sure the code is not optimized in any sort, but it's always solid as rock. When you need something tight, use ASM. Hence, for safety sake and for none 18Xxxxx your asm example could be...

ASM
    CHK?RP    ; make sure we are on the right BANK
here
    bsf PORTB,1
    NOP
    NOP
    bcf PORTB, 1
    goto here
ENDASM

PORTB.1=0 call MOVE?CT macro. wich is

MOVE?CT macro Cin, Regout, Bitout
        CHK?RP  Regout
    if (((Cin) & 1) == 1)
        bsf     Regout, Bitout
    else
        bcf     Regout, Bitout
    endif
    endm

there you discover the extra cycle

[therian]

separate coil-capacitor Oscillator and use pic only to turn on and of this oscillation we will get Pulse Modulation

[therian]

it sound too simple to be true