PIO (dis)assembler for RP2040

The idea:

A compact PIO forth style (dis)assembler for the RP2040 and mini-PIO control program.

Implementation

The example code asumes a 32-bit machine that has 32-bit compile actions. It is also asumed that the code runs in RAM as noForth T on the RP2040 does. All PIO fuctionality can be used, and a PIO-module EXPORT function is provided. The PIO-assembler is (de)activated by the words {PIO and PIO}. Missing words in Generic Forth are:

+TO         ( n "name" -- )     - Add n to the contents of the value "name"
VOCABULARY  ( "name" -- )       - Define a named wordlist

The structure of PIO opcodes

Pink   = Opcode field
Yellow = Delay and/or side set field
Green  = Destination field
Blue   = Data field

All PIO instructions

✦ PIO opcodes
    in,         out,        push,       pull,       mov,        wait,
    irq,        set,        nop,        pio,        
 
✦  Optional arguments for each opcode
    []         side
 
✦ Conditionals
    x0<>?       x--?        y0<>?       y--?        x=y?        pin?
    osre?
 
✦ Control structures
    if,         else,       then,      begin,      while,      repeat,
    again,      until,
 
✦ Labels
    one         two         one>        two>
 
✦ PIO directives
    clean-pio   =pio        sm          sync        restart
    =org        =set-pins   =out-pins   =side-pins  opt
    =in-pin     =jmp-pin    =inputs     =strength   side-pindirs
    wrap-target wrap        =steal      =autopush   =autopull
    =in-dir     =out-dir    clone       =exec       =clock-div
    =freq       export
 
✦ PIO external tools (mini-PIO.f)
    tx-depth    rx-depth    >txf        rxf>        set-pio
    sm-on       exec        freq        clock-div   sync
    restart
 
✦ PIO disassembler & state machine data
    mpsee       psee        .fifo       .sm

Usage example

decimal
: =BAUD ( b -- )    8 *  =freq ; \ Set baudrate for UART

clean-pio                   \ Empty code space, start at zero
0 0 {pio                    \ Use state machine-0 on PIO-0
    115200 =baud            \ 115k2
    26 1 =side-pins  opt    \ GPIO 26 for optional SIDE
    26 1 =out-pins          \ GPIO 26 for OUT & SET
    26 1 =set-pins
    1 pindirs set,              \ Pin is output!
    wrap-target
        7 []  1 side  pull,     \ Stop bit, get data byte
        7 []  0 side 7 x set,   \ Start bit
        begin,
            1 pins out,         \ Shift 8 bits out
        6 []  x--? until,       \ Until 8 bits are done
    wrap
    0 =exec                 \ Start SM-0 code at address 0
pio}

UART control code

: PEMIT ( ch -- )   begin  0 tx-depth  3 < until  0 >txf ;
: PTYPE ( a u -- )  0 ?do  count pemit  loop  drop ;
: ABC   ( -- )      s" ABC " ptype ;

File name	Purpose	in Dropbox (external link)
PIO-assembler docs.pdf	Documentation	PIO-assembler documentation
PIO assembler overview.pdf	Documentation	PIO-assembler overview
PIO-assembler uni.f	PIO-assembler	noForth PIO assembler
PIO-disassembler uni.f	PIO-disassembler	noForth PIO disassembler
Mini-PIO uni.f	mini-PIO tool set	noForth minimal PIO controller

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Contributions

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