'PIO frequency counter for PICOMITE MMBasic

'PIO program
'this PIO program samples the GPx pin for edges in 2 loops
'that are 2 instructions per loop so the resulting count is in
'ticks that are 2/f seconds. Each GPx period is 2 instructions off.
PIO assemble 0,".program period"
PIO assemble 0,".line 0"
pio assemble 0,".wrap target"
PIO assemble 0,"mov X,!null"
PIO assemble 0,"posloop:"
PIO assemble 0,"jmp pin negloop"
PIO assemble 0,"jmp x-- posloop"
PIO assemble 0,"negloop:"
PIO assemble 0,"jmp x-- next"
PIO assemble 0,"next:"
PIO assemble 0,"jmp pin negloop"
PIO assemble 0,"mov isr ,!x"
PIO assemble 0,"push noblock"
pio assemble 0,".wrap"
PIO assemble 0,".end program list"

'configure pio0
e=Pio(execctrl gp0,pio(.wrap target),pio(.wrap)) 'use gp0 for PIN
f=133e6                     '133MHz @ 2 instr per loop

'program pio0 and start
PIO init machine 0,0,f,0,e
PIO start 0,0

'pio fifo register
Dim h%(4)

'read counted time, average over 4, and convert to frequency
Do
 PIO read 0,0,5,h%()
 period=(h%(1)+h%(2)+h%(3)+h%(4))/4 + 2    'skip h%(0) = rubbish
                                           'correct loop delay
 Print f/(2*period);" Hz"                  'convert to the Hz
 Pause 1000
Loop While Inkey$=""
End