mirror of
https://github.com/arabine/open-story-teller.git
synced 2025-12-06 17:09:06 +01:00
82 lines
2.8 KiB
Text
82 lines
2.8 KiB
Text
; i2s.pio
|
|
;
|
|
; Author: Daniel Collins
|
|
; Date: 2022-02-25
|
|
;
|
|
; Copyright (c) 2022 Daniel Collins
|
|
;
|
|
; This file is part of rp2040_i2s_example.
|
|
;
|
|
; rp2040_i2s_example is free software: you can redistribute it and/or modify it under
|
|
; the terms of the GNU General Public License, version 3 as published by the
|
|
; Free Software Foundation.
|
|
;
|
|
; rp2040_i2s_example is distributed in the hope that it will be useful, but WITHOUT ANY
|
|
; WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
|
|
; A PARTICULAR PURPOSE. See the GNU General Public License for more details.
|
|
;
|
|
; You should have received a copy of the GNU General Public License along with
|
|
; rp2040_i2s_example. If not, see <https://www.gnu.org/licenses/>.
|
|
|
|
; An I2S bi-directional peripheral with master clock (SCK) output.
|
|
|
|
|
|
.program i2s_out_master
|
|
; I2S audio output block. Synchronous with clock and input.
|
|
; Must run at BCK * 2.
|
|
;
|
|
; This block also outputs the word clock (also called frame or LR clock) and
|
|
; the bit clock.
|
|
;
|
|
; Set register x to (bit depth - 2) (e.g. for 24 bit audio, set to 22).
|
|
; Note that if this is needed to be synchronous with the SCK module,
|
|
; it is not possible to run 24-bit frames with an SCK of 256x fs. You must either
|
|
; run SCK at 384x fs (if your codec permits this) or use 32-bit frames, which
|
|
; work fine with 24-bit codecs.
|
|
|
|
.side_set 2
|
|
|
|
public entry_point:
|
|
; /--- LRCLK
|
|
; |/-- BCLK
|
|
frameL: ; ||
|
|
set x, 30 side 0b00 ; start of Left frame
|
|
pull noblock side 0b01 ; One clock after edge change with no data
|
|
dataL:
|
|
out pins, 1 side 0b00
|
|
jmp x-- dataL side 0b01
|
|
|
|
frameR:
|
|
set x, 30 side 0b10
|
|
pull noblock side 0b11 ; One clock after edge change with no data
|
|
dataR:
|
|
out pins, 1 side 0b10
|
|
jmp x-- dataR side 0b11
|
|
|
|
|
|
% c-sdk {
|
|
|
|
// These constants are the I2S clock to pio clock ratio
|
|
const int i2s_sck_program_pio_mult = 2;
|
|
const int i2s_out_master_program_pio_mult = 2;
|
|
|
|
|
|
static inline void i2s_out_master_program_init(PIO pio, uint8_t sm, uint8_t offset, uint8_t bit_depth, uint8_t dout_pin, uint8_t clock_pin_base) {
|
|
pio_gpio_init(pio, dout_pin);
|
|
pio_gpio_init(pio, clock_pin_base);
|
|
pio_gpio_init(pio, clock_pin_base + 1);
|
|
|
|
pio_sm_config sm_config = i2s_out_master_program_get_default_config(offset);
|
|
sm_config_set_out_pins(&sm_config, dout_pin, 1);
|
|
sm_config_set_sideset_pins(&sm_config, clock_pin_base);
|
|
sm_config_set_out_shift(&sm_config, false, false, bit_depth);
|
|
sm_config_set_fifo_join(&sm_config, PIO_FIFO_JOIN_TX);
|
|
pio_sm_init(pio, sm, offset, &sm_config);
|
|
|
|
uint32_t pin_mask = (1u << dout_pin) | (3u << clock_pin_base);
|
|
pio_sm_set_pins_with_mask(pio, sm, 0, pin_mask); // zero output
|
|
pio_sm_set_pindirs_with_mask(pio, sm, pin_mask, pin_mask);
|
|
}
|
|
|
|
|
|
%} |