wavegen.pio

;
; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
;
; SPDX-License-Identifier: BSD-3-Clause
;

.program wavegen

; Repeatedly get one word of data from the TX FIFO, stalling when the FIFO is
; empty. Write the least significant bit to the OUT pin group.

.wrap_target
    out pins, 8
.wrap    

;loop:
;    pull
;    out pins, 2
;    jmp loop

% c-sdk {
static inline void wavegen_program_init(PIO pio, uint sm, uint offset, uint pin) {
    pio_sm_set_enabled(pio, sm, false);
    pio_sm_clear_fifos(pio, sm);
    pio_sm_restart(pio, sm);    
    
    pio_sm_config c = wavegen_program_get_default_config(offset);

    // Map the state machine's OUT pin group to one pin, namely the `pin`
    // parameter to this function.
    sm_config_set_out_pins(&c, pin, 8);
    // Set this pin's GPIO function (connect PIO to the pad)
    for(uint8_t i=0; i<8; i++)
        pio_gpio_init(pio, pin+i);
        
    // Set the pin direction to output at the PIO
    pio_sm_set_consecutive_pindirs(pio, sm, pin, 8, true);

    //sm_config_set_out_shift(&c, false, true, 8);
    sm_config_set_out_shift(&c, true, true, 8);

    sm_config_set_clkdiv(&c, 1);

    // Load our configuration, and jump to the start of the program
    pio_sm_init(pio, sm, offset, &c);
    // Set the state machine running
    pio_sm_set_enabled(pio, sm, true);

}
%}