pico_tnc/pico_tnc/pio_dac.pio

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;
; Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
;
; SPDX-License-Identifier: BSD-3-Clause
;
.program pio_dac
; 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, 1
.wrap
% c-sdk {
#include "hardware/clocks.h"
static inline void pio_dac_program_init(PIO pio, uint sm, uint offset, uint pin, float fs) {
pio_sm_config c = pio_dac_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_shift(&c, true, true, 32);
sm_config_set_out_pins(&c, pin, 1);
sm_config_set_clkdiv(&c, (float)clock_get_hz(clk_sys) / fs);
// Set this pin's GPIO function (connect PIO to the pad)
pio_gpio_init(pio, pin);
// Set the pin direction to output at the PIO
pio_sm_set_consecutive_pindirs(pio, sm, pin, 1, true);
// 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);
}
%}