P0 output

caskaz

Hi.
I have question.
I did below code.

CON
_clkmode = xtal1 + pll16x
_xinfreq = 5_000_000
PUB
cognew(@entry,0)

DAT
      org 0
entry mov outa #0
      mov dira,#1
      mov outa,#1

I checked P0 by oscilloscope.
There are low pulse(100nsec width) evry by 26usec.

Why low pulse?
And why every 26usec?

kwinn

That's how long it takes to execute the instructions in the rest of cog memory. You need to add a jump to "entry" at the bottom. Then the pin should toggle every 150nS ( 3.33MHz )

caskaz

Thanks kwinn.

I changed

        org 0
entry   mov outa #0
        mov dira,#1
        mov outa,#1
b       nop
        jmp b

It output pulse(high=150nsec Low=100nsec).
And why it become to low?

JasonDorie

You need this:

        org 0
entry   mov outa #0
        mov dira,#1
        mov outa,#1
b       nop
        jmp [COLOR="#B22222"]#b[/COLOR]

What your code is doing is jumping to the address in the memory location labelled 'b', not jumping to that literal address value. Since b is a nop, that memory location probably contains zero, which means your code is jumping back to 'entry'.

caskaz

Thank you, JasonDorie and kwinn
I understand it.