PIO_Builder

Single header C++14 library for runtime generation of RPi RP2040 PIO programs

See examples for example code. examples/i2c.cpp provides a good example of a more involved program, and the other examples show how to use PIOBuilder with the pico sdk.

It can be included as a header in any other project using the pico sdk, and just needs C++14 or later and to be linked against hardware_pio.

Features

See the RP2040 documentation for details of the PIO design.

A program can optionally have its number of side set pins, side set opt and side set pindirs set through template args, with defaults used otherwise

PIOBuilder::Program<SIDE_SET_PINS = 0, SIDE_SET_OPT = false, SIDE_SET_PINDIRS = false>

To create your own program, create a class deriving from PIOBuilder:

struct HelloPIO : public PIOBuilder::Program<> {
	HelloPIO() {
		auto loop = label();
		pull();
		out_pins(1);
		jmp(loop);
	}
};

The assembly language is meant to be very similar to pioasm. See pio_builder.hpp to see what options are available for each command.

pull_block(true);           // pull block
out_y(32);                  // out y, 32
mov(MovDest::X, MovSrc::Y); // mov x, y

Backward jumps can be created with a label() and jmp_* pair:

auto loop = label();
nop();
jmp(loop);

Forward jumps can be created with the jmp_fwd_* variants of jmp_* functions and a corresponding jmp_dest:

auto jmp_target = jmp_fwd();
nop();
jmp_dest(jmp_target);

Delay, side set, wrap and wrap_target can be set in the same way as pioasm:

wrap_target();
nop()    .side(1) [5];
nop()    .side(1) [5];
wrap();

The program can be loaded the PIOs similarly to the programs generated by pioasm:

HelloPIO my_program;

auto offset = pio_add_program(pio0, my_program);
// ...
pio_sm_config c = my_program.get_default_config(offset);
// ...