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Audio device driver for STM32F4xx PWM-based 8-bit DAC emulation

This commit is contained in:
Silvano Seva 2023-03-18 09:34:55 +01:00
parent efb5f22750
commit 5aed3e3316
2 changed files with 243 additions and 0 deletions
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174
platform/drivers/audio/stm32_pwm.cpp Normal file
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/***************************************************************************
* Copyright (C) 2023 by Federico Amedeo Izzo IU2NUO, *
* Niccolò Izzo IU2KIN *
* Frederik Saraci IU2NRO *
* Silvano Seva IU2KWO *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 3 of the License, or *
* (at your option) any later version. *
* *
* This program 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 this program; if not, see <http://www.gnu.org/licenses/> *
***************************************************************************/
#include <kernel/scheduler/scheduler.h>
#include <data_conversion.h>
#include <DmaStream.hpp>
#include <Timer.hpp>
#include <miosix.h>
#include <errno.h>
#include "stm32_pwm.h"
using Dma1_Stream2 = DmaStream< DMA1_BASE, 2, 1, 3 >; // DMA 1, Stream 2, channel 1, very high priority
static const struct PwmChannelCfg *config; // Config
static struct streamCtx *context; // Current stream context
static StreamHandler stream(Dma1_Stream2::init(10, DataSize::_16BIT, 1)); // DMA stream handler
static Timer tim(TIM7_BASE); // Trigger timebase
/**
* \internal
* Stop an ongoing transfer, deactivating timers and DMA stream.
*/
static void stopTransfer()
{
tim.stop();
config->stopCbk();
context->running = 0;
}
/**
* \internal
* Actual implementation of DMA interrupt handler.
*/
void __attribute__((used)) DMA_Handler()
{
Dma1_Stream2::IRQhandleInterrupt(&stream);
}
void __attribute__((naked)) DMA1_Stream2_IRQHandler()
{
saveContext();
asm volatile("bl _Z11DMA_Handlerv");
restoreContext();
}
void stm32pwm_init()
{
// Enable peripherals
RCC->APB1ENR |= RCC_APB1ENR_TIM7EN;
__DSB();
// Init DMA stream
stream.setEndTransferCallback(stopTransfer);
}
void stm32pwm_terminate()
{
if(stream.running())
stream.halt();
RCC->APB1ENR &= ~RCC_APB1ENR_TIM7EN;
__DSB();
}
static int stm32pwm_start(const uint8_t instance, const void *cfg,
struct streamCtx *ctx)
{
(void) instance;
if(ctx == NULL)
return -EINVAL;
if((ctx->running != 0) || stream.running())
return -EBUSY;
__disable_irq();
ctx->running = 1;
__enable_irq();
context = ctx;
config = reinterpret_cast< const struct PwmChannelCfg *>(cfg);
/*
* Convert buffer elements from int16_t to unsigned 12 bit values as required
* by the DAC. Processing can be done in-place because the API mandates that
* the function caller does not modify the buffer content once this function
* has been called.
*/
S16toU8(ctx->buffer, ctx->bufSize);
bool circ = false;
if(ctx->bufMode == BUF_CIRC_DOUBLE)
circ = true;
stream.start(config->pwmReg, ctx->buffer, ctx->bufSize, circ);
config->startCbk();
// Configure trigger
tim.setUpdateFrequency(ctx->sampleRate);
tim.enableDmaTrigger(true);
tim.start();
return 0;
}
static int stm32pwm_idleBuf(struct streamCtx *ctx, stream_sample_t **buf)
{
*buf = reinterpret_cast< stream_sample_t *>(stream.idleBuf());
return ctx->bufSize/2;
}
static int stm32pwm_sync(struct streamCtx *ctx, uint8_t dirty)
{
if((ctx->bufMode == BUF_CIRC_DOUBLE) && (dirty != 0))
{
void *ptr = stream.idleBuf();
S16toU8(reinterpret_cast< int16_t *>(ptr), ctx->bufSize/2);
}
bool ok = stream.sync();
if(ok) return 0;
return -1;
}
static void stm32pwm_stop(struct streamCtx *ctx)
{
if(ctx->running == 0)
return;
stream.stop();
}
static void stm32pwm_halt(struct streamCtx *ctx)
{
if(ctx->running == 0)
return;
stream.halt();
}
#pragma GCC diagnostic ignored "-Wpedantic"
const struct audioDriver stm32_pwm_audio_driver =
{
.start = stm32pwm_start,
.data = stm32pwm_idleBuf,
.sync = stm32pwm_sync,
.stop = stm32pwm_stop,
.terminate = stm32pwm_halt
};
#pragma GCC diagnostic pop

69
platform/drivers/audio/stm32_pwm.h Normal file
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/***************************************************************************
* Copyright (C) 2023 by Federico Amedeo Izzo IU2NUO, *
* Niccolò Izzo IU2KIN *
* Frederik Saraci IU2NRO *
* Silvano Seva IU2KWO *
* *
* This program is free software; you can redistribute it and/or modify *
* it under the terms of the GNU General Public License as published by *
* the Free Software Foundation; either version 3 of the License, or *
* (at your option) any later version. *
* *
* This program 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 this program; if not, see <http://www.gnu.org/licenses/> *
***************************************************************************/
#ifndef STM32_PWM_H
#define STM32_PWM_H
#include <stdbool.h>
#include <stdint.h>
#include <stm32f4xx.h>
#include <interfaces/audio.h>
#ifdef __cplusplus
extern "C" {
#endif
/**
* Driver STM32 PWM used as audio output stream device.
* Input data format is signed 16-bit, internally converted to unsigned 8-bit
* values for compatibility with the hardware.
*
* The driver uses the following peripherals: DMA1_Stream2, TIM7
*/
/**
* Data structure holding the configuration for a given DAC channel.
*/
struct PwmChannelCfg
{
volatile uint32_t *pwmReg; ///< Address of PWM duty cycle register.
void (*startCbk)(void); ///< Callback function for additional setup operations.
void (*stopCbk)(void); ///< Callback function for additional end operations.
};
extern const struct audioDriver stm32_pwm_audio_driver;
/**
* Initialize the driver and the peripherals.
*/
void stm32pwm_init();
/**
* Shutdown the driver and the peripherals.
*/
void stm32pwm_terminate();
#ifdef __cplusplus
}
#endif
#endif /* STM32_PWM_H */