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circuitpython/ports/nrf/common-hal/audiopwmio/PWMAudioOut.c

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/*
* This file is part of the MicroPython project, http://micropython.org/
*
* The MIT License (MIT)
*
* Copyright (c) 2019 Jeff Epler for Adafruit Industries
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stdint.h>
#include <string.h>
#include "extmod/vfs_fat.h"
#include "py/gc.h"
#include "py/mperrno.h"
#include "py/runtime.h"
#include "common-hal/audiopwmio/PWMAudioOut.h"
#include "common-hal/pwmio/PWMOut.h"
#include "shared-bindings/audiopwmio/PWMAudioOut.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/microcontroller/Pin.h"
#include "supervisor/shared/tick.h"
// TODO: This should be the same size as PWMOut.c:pwms[], but there's no trivial way to accomplish that
STATIC audiopwmio_pwmaudioout_obj_t *active_audio[4];
#define F_TARGET (62500)
#define F_PWM (16000000)
// return the REFRESH value, store the TOP value in an out-parameter
// Tested for key values (worst relative error = 0.224% = 3.84 cents)
// 8000: top = 250 refresh = 7 [ 8000.0]
// 22050: top = 242 refresh = 2 [22038.5]
// 24000: top = 222 refresh = 2 [24024.0]
// 44100: top = 181 refresh = 1 [44198.8]
// 48000: top = 167 refresh = 1 [47904.1]
STATIC uint32_t calculate_pwm_parameters(uint32_t sample_rate, uint32_t *top_out) {
// the desired frequency is the closest integer multiple of sample_rate not less than F_TARGET
uint32_t desired_frequency = (F_TARGET + sample_rate - 1) / sample_rate * sample_rate;
// The top value is the PWM frequency divided by the desired frequency (round to nearest)
uint32_t top = (F_PWM + desired_frequency / 2) / desired_frequency;
// The actual frequency is the PWM frequency divided by the top value (round to nearest)
uint32_t actual_frequency = (F_PWM + top / 2) / top;
// The multiplier is the actual frequency divided by the sample rate (round to nearest)
uint32_t multiplier = (actual_frequency + sample_rate / 2) / sample_rate;
*top_out = top;
return multiplier - 1;
}
STATIC void activate_audiopwmout_obj(audiopwmio_pwmaudioout_obj_t *self) {
for (size_t i = 0; i < MP_ARRAY_SIZE(active_audio); i++) {
if (!active_audio[i]) {
active_audio[i] = self;
supervisor_enable_tick();
break;
}
}
}
STATIC void deactivate_audiopwmout_obj(audiopwmio_pwmaudioout_obj_t *self) {
// Turn off the interrupts to the CPU.
self->pwm->INTENCLR = PWM_INTENSET_SEQSTARTED0_Msk | PWM_INTENSET_SEQSTARTED1_Msk;
for (size_t i = 0; i < MP_ARRAY_SIZE(active_audio); i++) {
if (active_audio[i] == self) {
active_audio[i] = NULL;
supervisor_disable_tick();
}
}
}
void audiopwmout_reset() {
for (size_t i = 0; i < MP_ARRAY_SIZE(active_audio); i++) {
if (active_audio[i]) {
supervisor_disable_tick();
}
active_audio[i] = NULL;
}
}
STATIC void fill_buffers(audiopwmio_pwmaudioout_obj_t *self, int buf) {
uint16_t *dev_buffer = self->buffers[buf];
uint8_t *buffer;
uint32_t buffer_length;
audioio_get_buffer_result_t get_buffer_result =
audiosample_get_buffer(self->sample, false, 0,
&buffer, &buffer_length);
if (get_buffer_result == GET_BUFFER_ERROR) {
common_hal_audiopwmio_pwmaudioout_stop(self);
return;
}
uint32_t num_samples = buffer_length / self->bytes_per_sample / self->sample_channel_count;
uint16_t *end_dev_buffer = dev_buffer + 2 * num_samples;
if (self->bytes_per_sample == 1) {
uint8_t offset = self->signed_to_unsigned ? 0x80 : 0;
uint16_t scale = self->scale;
while (dev_buffer < end_dev_buffer) {
uint8_t rawval = (*buffer++ + offset);
uint16_t val = (uint16_t)(((uint32_t)rawval * (uint32_t)scale) >> 8);
*dev_buffer++ = val;
if (self->sample_channel_count == 1) {
*dev_buffer++ = val;
}
}
} else {
uint16_t offset = self->signed_to_unsigned ? 0x8000 : 0;
uint16_t scale = self->scale;
uint16_t *buffer16 = (uint16_t *)buffer;
while (dev_buffer < end_dev_buffer) {
uint16_t rawval = (*buffer16++ + offset);
uint16_t val = (uint16_t)((rawval * (uint32_t)scale) >> 16);
*dev_buffer++ = val;
if (self->sample_channel_count == 1) {
*dev_buffer++ = val;
}
}
}
self->pwm->SEQ[buf].PTR = (intptr_t)self->buffers[buf];
self->pwm->SEQ[buf].CNT = num_samples * 2;
if (self->loop && get_buffer_result == GET_BUFFER_DONE) {
audiosample_reset_buffer(self->sample, false, 0);
} else if (get_buffer_result == GET_BUFFER_DONE) {
self->pwm->SHORTS = NRF_PWM_SHORT_SEQEND0_STOP_MASK | NRF_PWM_SHORT_SEQEND1_STOP_MASK;
self->stopping = true;
}
}
STATIC void audiopwmout_background_obj(audiopwmio_pwmaudioout_obj_t *self) {
if (!common_hal_audiopwmio_pwmaudioout_get_playing(self)) {
return;
}
if (self->stopping) {
bool stopped =
(self->pwm->EVENTS_SEQEND[0] || !self->pwm->EVENTS_SEQSTARTED[0]) &&
(self->pwm->EVENTS_SEQEND[1] || !self->pwm->EVENTS_SEQSTARTED[1]);
if (stopped) {
self->pwm->TASKS_STOP = 1;
}
} else if (!self->paused && !self->single_buffer) {
if (self->pwm->EVENTS_SEQSTARTED[0]) {
fill_buffers(self, 1);
self->pwm->EVENTS_SEQSTARTED[0] = 0;
}
if (self->pwm->EVENTS_SEQSTARTED[1]) {
fill_buffers(self, 0);
self->pwm->EVENTS_SEQSTARTED[1] = 0;
}
NVIC_ClearPendingIRQ(self->pwm_irq);
}
}
void audiopwmout_background() {
// Check the NVIC first because it is part of the CPU and fast to read.
if (!NVIC_GetPendingIRQ(PWM0_IRQn) &&
!NVIC_GetPendingIRQ(PWM1_IRQn) &&
!NVIC_GetPendingIRQ(PWM2_IRQn) &&
!NVIC_GetPendingIRQ(PWM3_IRQn)) {
return;
}
// Check our objects because the PWM could be active for some other reason.
for (size_t i = 0; i < MP_ARRAY_SIZE(active_audio); i++) {
if (!active_audio[i]) {
continue;
}
audiopwmout_background_obj(active_audio[i]);
}
}
// Caller validates that pins are free.
void common_hal_audiopwmio_pwmaudioout_construct(audiopwmio_pwmaudioout_obj_t *self,
const mcu_pin_obj_t *left_channel, const mcu_pin_obj_t *right_channel, uint16_t quiescent_value) {
self->pwm = pwmout_allocate(256, PWM_PRESCALER_PRESCALER_DIV_1, true, NULL, NULL,
&self->pwm_irq);
if (!self->pwm) {
mp_raise_RuntimeError(translate("All timers in use"));
}
self->pwm->PRESCALER = PWM_PRESCALER_PRESCALER_DIV_1;
// two uint16_t values per sample when Grouped
// n.b. SEQ[#].CNT "counts" are 2 per sample (left and right channels)
self->pwm->DECODER = PWM_DECODER_LOAD_Grouped;
// we use channels 0 and 2 because these are GROUPED; it lets us save half
// the space for sample data (no additional optimization is possible for
// single channel)
self->pwm->PSEL.OUT[0] = self->left_channel_number = left_channel->number;
claim_pin(left_channel);
if (right_channel) {
self->pwm->PSEL.OUT[2] = self->right_channel_number = right_channel->number;
claim_pin(right_channel);
}
self->quiescent_value = quiescent_value >> 8;
self->pwm->ENABLE = 1;
// TODO: Ramp from 0 to quiescent value
}
bool common_hal_audiopwmio_pwmaudioout_deinited(audiopwmio_pwmaudioout_obj_t *self) {
return !self->pwm;
}
void common_hal_audiopwmio_pwmaudioout_deinit(audiopwmio_pwmaudioout_obj_t *self) {
if (common_hal_audiopwmio_pwmaudioout_deinited(self)) {
return;
}
deactivate_audiopwmout_obj(self);
// TODO: ramp the pwm down from quiescent value to 0
self->pwm->ENABLE = 0;
if (self->left_channel_number) {
reset_pin_number(self->left_channel_number);
}
if (self->right_channel_number) {
reset_pin_number(self->right_channel_number);
}
pwmout_free_channel(self->pwm, 0);
pwmout_free_channel(self->pwm, 2);
self->pwm = NULL;
m_free(self->buffers[0]);
self->buffers[0] = NULL;
m_free(self->buffers[1]);
self->buffers[1] = NULL;
}
void common_hal_audiopwmio_pwmaudioout_play(audiopwmio_pwmaudioout_obj_t *self, mp_obj_t sample, bool loop) {
if (common_hal_audiopwmio_pwmaudioout_get_playing(self)) {
common_hal_audiopwmio_pwmaudioout_stop(self);
}
self->sample = sample;
self->loop = loop;
uint32_t sample_rate = audiosample_sample_rate(sample);
self->bytes_per_sample = audiosample_bits_per_sample(sample) / 8;
uint32_t max_buffer_length;
uint8_t spacing;
audiosample_get_buffer_structure(sample, /* single channel */ false,
&self->single_buffer, &self->signed_to_unsigned, &max_buffer_length,
&spacing);
self->sample_channel_count = audiosample_channel_count(sample);
mp_arg_validate_length_max(max_buffer_length, UINT16_MAX, MP_QSTR_buffer);
uint16_t buffer_length = (uint16_t)max_buffer_length;
self->buffers[0] = m_malloc(buffer_length * 2 * sizeof(uint16_t));
if (!self->single_buffer) {
self->buffers[1] = m_malloc(buffer_length * 2 * sizeof(uint16_t));
}
uint32_t top;
self->pwm->SEQ[0].REFRESH = self->pwm->SEQ[1].REFRESH = calculate_pwm_parameters(sample_rate, &top);
self->scale = top - 1;
self->pwm->COUNTERTOP = top;
self->pwm->LOOP = 1;
audiosample_reset_buffer(self->sample, false, 0);
activate_audiopwmout_obj(self);
self->stopping = false;
self->pwm->SHORTS = NRF_PWM_SHORT_LOOPSDONE_SEQSTART0_MASK;
fill_buffers(self, 0);
self->pwm->SEQ[1].PTR = self->pwm->SEQ[0].PTR;
self->pwm->SEQ[1].CNT = self->pwm->SEQ[0].CNT;
self->pwm->EVENTS_SEQSTARTED[0] = 0;
self->pwm->EVENTS_SEQSTARTED[1] = 0;
self->pwm->EVENTS_SEQEND[0] = 0;
self->pwm->EVENTS_SEQEND[1] = 0;
self->pwm->EVENTS_STOPPED = 0;
// Enable the SEQSTARTED interrupts so that they wake the CPU and keep it awake until serviced.
// We don't enable them in the NVIC because we don't actually want an interrupt routine to run.
self->pwm->INTENSET = PWM_INTENSET_SEQSTARTED0_Msk | PWM_INTENSET_SEQSTARTED1_Msk;
self->pwm->TASKS_SEQSTART[0] = 1;
self->playing = true;
self->paused = false;
}
void common_hal_audiopwmio_pwmaudioout_stop(audiopwmio_pwmaudioout_obj_t *self) {
deactivate_audiopwmout_obj(self);
self->pwm->TASKS_STOP = 1;
self->stopping = false;
self->paused = false;
m_free(self->buffers[0]);
self->buffers[0] = NULL;
m_free(self->buffers[1]);
self->buffers[1] = NULL;
}
bool common_hal_audiopwmio_pwmaudioout_get_playing(audiopwmio_pwmaudioout_obj_t *self) {
if (!self->paused && self->pwm->EVENTS_STOPPED) {
self->playing = false;
self->pwm->EVENTS_STOPPED = 0;
}
return self->playing;
}
/* pause/resume present difficulties for the NRF PWM audio module.
*
* A PWM sequence can be stopped in its tracks by sending a TASKS_STOP event,
* but there's no way to pick up the sequence where it was stopped; you could
* start at the start of one of the two sequences, but especially for "single buffer"
* sample, this seems undesirable.
*
* Or, you can stop at the end of a sequence so that you don't duplicate anything
* when restarting, but again this is unsatisfactory for a "single buffer" sample.
*
* For now, I've taken the coward's way and left these methods unimplemented.
* Perhaps the way forward is to divide even "single buffer" samples into tasks of
* only a few ms long, so that they can be stopped/restarted quickly enough that it
* feels instant. (This also saves on memory, for long in-memory "single buffer"
* samples, since we have to locally take a resampled copy!)
*/
void common_hal_audiopwmio_pwmaudioout_pause(audiopwmio_pwmaudioout_obj_t *self) {
self->paused = true;
self->pwm->SHORTS = NRF_PWM_SHORT_SEQEND1_STOP_MASK;
}
void common_hal_audiopwmio_pwmaudioout_resume(audiopwmio_pwmaudioout_obj_t *self) {
self->paused = false;
self->pwm->SHORTS = NRF_PWM_SHORT_LOOPSDONE_SEQSTART0_MASK;
if (self->pwm->EVENTS_STOPPED) {
self->pwm->EVENTS_STOPPED = 0;
self->pwm->TASKS_SEQSTART[0] = 1;
}
}
bool common_hal_audiopwmio_pwmaudioout_get_paused(audiopwmio_pwmaudioout_obj_t *self) {
return self->paused;
}
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