Guru
Joined: 05/03/2018
Location: NetherlandsPosts: 4722
| Posted: 03:59pm 30 Jan 2025 |
Hi Kevin,
Here you go. This toggles GP0 at half the PIO clock speed.
Change the f0 value according your wishes.
setpin gp0,PIO1
PIO ASSEMBLE 1,".program toggle"
pio assemble 1,".line 0" 'start line 0
PIO ASSEMBLE 1,"set pindirs,1" 'set GPIO to output
PIO ASSEMBLE 1,".wrap target"
PIO ASSEMBLE 1,"set pins,0" 'set low
PIO ASSEMBLE 1,"set pins,1" 'set high
PIO ASSEMBLE 1,".wrap" 'wrap back to wrap_target
PIO ASSEMBLE 1,".end program list"
'configure pio1 StateMachine 0
f0 = 133e6 '1MHz, change this to meet your need
' a b c d e f g 'a,e=side set c,g=OUT b,f=set
p0 = Pio(PINCTRL 0,1,,,,GP0,)
e0 = Pio(EXECCTRL GP0,Pio(.wrap target),Pio(.wrap))
'write the configuration
PIO init machine 1,0,f0,p0,e0,,0 'SM0 start at address 0
PIO START 1,0
do:loop
PIO ASSEMBLE 1,".program toggle"
pio assemble 1,".line 0" 'start line 0
PIO ASSEMBLE 1,"set pindirs,1" 'set GPIO to output
PIO ASSEMBLE 1,".wrap target"
PIO ASSEMBLE 1,"set pins,0" 'set low
PIO ASSEMBLE 1,"set pins,1" 'set high
PIO ASSEMBLE 1,".wrap" 'wrap back to wrap_target
PIO ASSEMBLE 1,".end program list"
'configure pio1 StateMachine 0
f0 = 133e6 '1MHz, change this to meet your need
' a b c d e f g 'a,e=side set c,g=OUT b,f=set
p0 = Pio(PINCTRL 0,1,,,,GP0,)
e0 = Pio(EXECCTRL GP0,Pio(.wrap target),Pio(.wrap))
'write the configuration
PIO init machine 1,0,f0,p0,e0,,0 'SM0 start at address 0
PIO START 1,0
do:loop
Theoretically you can set the PIO clock frequency to the same value as the ARM speed.
But if PIO can really do 400MHz I am not sure. Try it.
Another problem may be the IO pin that cannot toggle fast enough. At 200MHz, you may see a sine wave half the 3.3V amplitude. Becuase that is all the IO pin silicon can do.
Volhout
P.S. if you want to use a different GPIO pin, change the GP0 in PINCTRL. The one in EXECCTRL is a dummy, and can stay the same.
Edited 2025-01-31 02:14 by Volhout