' demo program to demonstrate the use of the PIO interrupt
' the PIO is programmed to pull 1 word from FIFO at every rising edge of the GP0 pin.
' the GP0 pin is controlled from MMBasic in this demo, but could also be driven from
' an external source.
 
'-------------------------------- PIO state machine -----------------------------------
 
'PIO clear
 pio clear 1
 
'the PIO program
'address    code    mnemonics         comment
'  0      2000      WAIT GP0=0
'  1      2080      WAIT GP0=1
'  2      8080      PULL noblock
'  3      0000      JMP 0
 
'program pio1
 pio program line 1,0,&h2000
 pio program line 1,1,&h2080
 pio program line 1,2,&h8080
 PIO program line 1,3,&h0000
 
'write the configuration, running 100kHz (data in FIFO pulled 10us after rising edge GP0)
 PIO init machine 1,0,1e5,0,,,0
 
 
 
'-------------------------------- MMBasic MAIN ---------------------------------------
 
'Halt the PIO from GP0 from MMBasic before it fills the FIFO out of control
 setpin gp0,dout
 pin(gp0)=0
 
'variables
 dim size%=10
 dim d%(size%)'=(....) fill with data
 dim pointer%=0  'points to first array cell
 dim repeat%=0   '0=do we stop, 1=repeat sending data
 dim ready%=0    '0=running, 1=we are done...
 
'start the pio1 code, state machine 1.0 will be waiting for a rising edge on the GP0 pin
'then it will pull 1 word from fifo. Then it will wait for the falling edge. The cycle repeats.
 PIO start 1,0
 
'interrupt format PIO INTERRUPT PIO,SM,RX_SUB,TX_SUB
 PIO interrupt 1,0,OFF,FeedFifo
 
'freguently PIO pull data from the fifo
 Settick 100,PullFifo
 
'Main: check if data transfer is ready, when yes, then stop interrupt
 do
   if ready%=1 then
     print "done, stop PIO"
     pio stop 1,0
   else
     print "still running"
   end if
   pause 200
 loop
 
 
 
'----------------------------------- SUBS ---------------------------------------
 
'in this sub write 1 word to the Fifo. We can expand that to write more data until
'the fifo is full by repeated write and check of the fifo full flag.
SUB FeedFifo
 PIO write 1,0,1,d%(pointer%)
 inc pointer%,1
 if pointer%=size% then
   if repeat%=1 then
     pointer%=0
   else
     ready%=1
     pio interrupt 1,0,off,off 'stop interrupt
   end if
 end if
end sub
 
'in this sub we toggle the GP0 pin to force the PIO to fetch data from the FIFO
sub PullFifo
 pin(gp0)=1:pause 1:pin(gp0)=0:pause 1
end sub
 
 

cat tm$, ":"

inc tm$, ":"

'
DIM b%, n% =1, k% = 1
SETPIN GP23, DOUT
DO
BITBANG WS2812 O, GP23, 1, b%
PAUSE 300
b% = RGB(n%,n%,n%)
n% = n% + k%
IF n% >= 32 THEN k% = -1
'if n% <= 1 then k% = 1
IF n% = 0 THEN k% = 1 ' this is the faulty line
LOOP UNTIL INKEY$ <>""
BITBANG WS2812 O, GP23, 1, 0