/* * This file is part of the MicroPython project, http://micropython.org/ * * The MIT License (MIT) * * Copyright (c) 2021 Scott Shawcroft 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 #include #include #include "py/mperrno.h" #include "py/runtime.h" #include "shared-bindings/audiobusio/PDMIn.h" #include "shared-bindings/microcontroller/Pin.h" #include "supervisor/shared/translate.h" #include "audio_dma.h" #define OVERSAMPLING 64 #define SAMPLES_PER_BUFFER 32 // MEMS microphones must be clocked at at least 1MHz. #define MIN_MIC_CLOCK 1000000 const uint16_t pdmin[] = { // in pins 1 side 0b1 0x5001, // push iffull side 0b0 0x8040 }; // Caller validates that pins are free. void common_hal_audiobusio_pdmin_construct(audiobusio_pdmin_obj_t *self, const mcu_pin_obj_t *clock_pin, const mcu_pin_obj_t *data_pin, uint32_t sample_rate, uint8_t bit_depth, bool mono, uint8_t oversample) { if (!(bit_depth == 16 || bit_depth == 8) || !mono || oversample != OVERSAMPLING) { mp_raise_NotImplementedError(translate("Only 8 or 16 bit mono with " MP_STRINGIFY(OVERSAMPLING) "x oversampling is supported.")); } // Use the state machine to manage pins. common_hal_rp2pio_statemachine_construct(&self->state_machine, pdmin, sizeof(pdmin) / sizeof(pdmin[0]), 44100 * 32 * 2, // Clock at 44.1 khz to warm the DAC up. NULL, 0, NULL, 1, 0, 0xffffffff, // out pin data_pin, 1, // in pins 0, 0, // in pulls NULL, 0, 0, 0x1f, // set pins clock_pin, 1, 0, 0x1f, // sideset pins false, // No sideset enable NULL, // jump pin 0, // wait gpio pins true, // exclusive pin use false, 32, false, // out settings false, // Wait for txstall false, 32, true, // in settings false); // Not user-interruptible. uint32_t actual_frequency = common_hal_rp2pio_statemachine_get_frequency(&self->state_machine); if (actual_frequency < MIN_MIC_CLOCK) { mp_raise_ValueError(translate("sampling rate out of range")); } self->sample_rate = actual_frequency / oversample; self->bit_depth = bit_depth; } bool common_hal_audiobusio_pdmin_deinited(audiobusio_pdmin_obj_t *self) { return common_hal_rp2pio_statemachine_deinited(&self->state_machine); } void common_hal_audiobusio_pdmin_deinit(audiobusio_pdmin_obj_t *self) { if (common_hal_audiobusio_pdmin_deinited(self)) { return; } return common_hal_rp2pio_statemachine_deinit(&self->state_machine); } uint8_t common_hal_audiobusio_pdmin_get_bit_depth(audiobusio_pdmin_obj_t *self) { return self->bit_depth; } uint32_t common_hal_audiobusio_pdmin_get_sample_rate(audiobusio_pdmin_obj_t *self) { return self->sample_rate; } // a windowed sinc filter for 44 khz, 64 samples // // This filter is good enough to use for lower sample rates as // well. It does not increase the noise enough to be a problem. // // In the long run we could use a fast filter like this to do the // decimation and initial filtering in real time, filtering to a // higher sample rate than specified. Then after the audio is // recorded, a more expensive filter non-real-time filter could be // used to down-sample and low-pass. const uint16_t sinc_filter[OVERSAMPLING] = { 0, 2, 9, 21, 39, 63, 94, 132, 179, 236, 302, 379, 467, 565, 674, 792, 920, 1055, 1196, 1341, 1487, 1633, 1776, 1913, 2042, 2159, 2263, 2352, 2422, 2474, 2506, 2516, 2506, 2474, 2422, 2352, 2263, 2159, 2042, 1913, 1776, 1633, 1487, 1341, 1196, 1055, 920, 792, 674, 565, 467, 379, 302, 236, 179, 132, 94, 63, 39, 21, 9, 2, 0, 0 }; #define REPEAT_32_TIMES(X) do { X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X } while (0) static uint16_t filter_sample(uint32_t pdm_samples[2]) { uint16_t running_sum = 0; const uint16_t *filter_ptr = sinc_filter; for (uint8_t i = 0; i < 2; i++) { uint32_t pdm_sample = pdm_samples[i]; REPEAT_32_TIMES({ if (pdm_sample & 0x1) { running_sum += *filter_ptr; } filter_ptr++; pdm_sample >>= 1; } ); } return running_sum; } // output_buffer may be a byte buffer or a halfword buffer. // output_buffer_length is the number of slots, not the number of bytes. uint32_t common_hal_audiobusio_pdmin_record_to_buffer(audiobusio_pdmin_obj_t *self, uint16_t *output_buffer, uint32_t output_buffer_length) { uint32_t samples[2]; size_t output_count = 0; common_hal_rp2pio_statemachine_clear_rxfifo(&self->state_machine); // Do one read to get the mic going and throw it away. common_hal_rp2pio_statemachine_readinto(&self->state_machine, (uint8_t *)samples, 2 * sizeof(uint32_t), sizeof(uint32_t)); while (output_count < output_buffer_length && !common_hal_rp2pio_statemachine_get_rxstall(&self->state_machine)) { common_hal_rp2pio_statemachine_readinto(&self->state_machine, (uint8_t *)samples, 2 * sizeof(uint32_t), sizeof(uint32_t)); // Call filter_sample just one place so it can be inlined. uint16_t value = filter_sample(samples); if (self->bit_depth == 8) { // Truncate to 8 bits. ((uint8_t *)output_buffer)[output_count] = value >> 8; } else { output_buffer[output_count] = value; } output_count++; } return output_count; }