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.
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, yBackward 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);
// ...