circuitpython/stm/audio.c

99 lines
2.8 KiB
C

#include <stdint.h>
#include "stm32f4xx_rcc.h"
#include "stm32f4xx_gpio.h"
#include "stm32f4xx_dac.h"
#include "nlr.h"
#include "misc.h"
#include "mpyconfig.h"
#include "parse.h"
#include "compile.h"
#include "runtime.h"
#include "audio.h"
#define SAMPLE_BUF_SIZE (32)
// sample_buf_in is always the same or ahead of sample_buf_out
// when they are the same, there are no more samples left to process
// in this scheme, there is always 1 unusable byte in the buffer, just before sample_buf_out
int sample_buf_in;
int sample_buf_out;
byte sample_buf[SAMPLE_BUF_SIZE];
bool audio_is_full(void) {
return ((sample_buf_in + 1) % SAMPLE_BUF_SIZE) == sample_buf_out;
}
void audio_fill(byte sample) {
sample_buf[sample_buf_in] = sample;
sample_buf_in = (sample_buf_in + 1) % SAMPLE_BUF_SIZE;
// enable interrupt
}
void audio_drain(void) {
if (sample_buf_in == sample_buf_out) {
// buffer is empty; disable interrupt
} else {
// buffer has a sample; output it
byte sample = sample_buf[sample_buf_out];
DAC_SetChannel2Data(DAC_Align_8b_R, sample);
sample_buf_out = (sample_buf_out + 1) % SAMPLE_BUF_SIZE;
}
}
// direct access to DAC
py_obj_t pyb_audio_dac(py_obj_t val) {
DAC_SetChannel2Data(DAC_Align_8b_R, py_obj_get_int(val));
return py_const_none;
}
py_obj_t pyb_audio_is_full(void) {
if (audio_is_full()) {
return py_const_true;
} else {
return py_const_false;
}
}
py_obj_t pyb_audio_fill(py_obj_t val) {
audio_fill(py_obj_get_int(val));
return py_const_none;
}
void audio_init(void) {
// DAC peripheral clock
RCC_APB1PeriphClockCmd(RCC_APB1Periph_DAC, ENABLE);
// DAC channel 2 (DAC_OUT2 = PA.5) configuration
GPIO_InitTypeDef GPIO_InitStructure;
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AN;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_NOPULL;
GPIO_Init(GPIOA, &GPIO_InitStructure);
// DAC channel2 Configuration
DAC_InitTypeDef DAC_InitStructure;
DAC_InitStructure.DAC_Trigger = DAC_Trigger_None;
DAC_InitStructure.DAC_WaveGeneration = DAC_WaveGeneration_None;
DAC_InitStructure.DAC_OutputBuffer = DAC_OutputBuffer_Enable;
DAC_Init(DAC_Channel_2, &DAC_InitStructure);
// Enable DAC Channel2
DAC_Cmd(DAC_Channel_2, ENABLE);
// from now on use DAC_SetChannel2Data to trigger a conversion
sample_buf_in = 0;
sample_buf_out = 0;
// enable interrupt
// Python interface
py_obj_t m = py_module_new();
rt_store_attr(m, qstr_from_str_static("dac"), rt_make_function_1(pyb_audio_dac));
rt_store_attr(m, qstr_from_str_static("is_full"), rt_make_function_0(pyb_audio_is_full));
rt_store_attr(m, qstr_from_str_static("fill"), rt_make_function_1(pyb_audio_fill));
rt_store_name(qstr_from_str_static("audio"), m);
}