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pio

Provides clean API to interact with RP2040's on-board Programable Input/Output (PIO) block. See chapter 3 of the RP2040 datasheet for more information.

piolib

This module contains the piolib package which contains importable drivers for use with a PIO such as:

  • SPI driver
  • 8-pin send-only parallel bus
  • WS2812 (Neopixel) driver
  • A pulse-constrained square wave generator (Pulsar)

Introduction to PIO

The PIO is a versatile hardware interface. It can support a variety of IO standards, including:

  • 8080 and 6800 parallel bus
  • I2C
  • 3-pin I2S
  • SDIO
  • SPI, DSPI, QSPI
  • UART
  • DPI or VGA (via resistor DAC)

PIO is programmable in the same sense as a processor and has a total of nine instructions: JMP, WAIT, IN, OUT, PUSH, PULL, MOV, IRQ, and SET. These are programmed in PIO assembly format describing a PIO program, where each command corresponds to one instruction in the output binary. Below is an example program in PIO assembly:

.program squarewave
again:
    set pins, 1 [1] ; Drive pin high and then delay for one cycle
    set pins, 0     ; Drive pin low
    jmp again       ; Set PC to label `again`