pio_serialiser.pio

;
; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
;
; SPDX-License-Identifier: BSD-3-Clause
;
; Just serialise a stream of bits. Take 32 bits from each FIFO record. LSB-first.

.program pio_serialiser

.wrap_target
    out pins, 1
.wrap

% c-sdk {
static inline void pio_serialiser_program_init(PIO pio, uint sm, uint offset, uint data_pin, float clk_div) {
    pio_gpio_init(pio, data_pin);
    gpio_set_drive_strength(data_pin, GPIO_DRIVE_STRENGTH_12MA);
    gpio_set_slew_rate(data_pin, GPIO_SLEW_RATE_FAST);
    pio_sm_set_consecutive_pindirs(pio, sm, data_pin, 1, true);
    pio_sm_config c = pio_serialiser_program_get_default_config(offset);
    sm_config_set_out_pins(&c, data_pin, 1);
    sm_config_set_fifo_join(&c, PIO_FIFO_JOIN_TX);
    sm_config_set_clkdiv(&c, clk_div);
    // shift right
    sm_config_set_out_shift(&c, false, true, 32);
    pio_sm_init(pio, sm, offset, &c);
    pio_sm_set_enabled(pio, sm, true);
}
%}