STM32F4xx: driver for ADC peripherals

meson.build

@@ -214,6 +214,7 @@ stm32f405_src = ['platform/mcu/STM32F4xx/boot/startup.cpp',
                  'platform/mcu/STM32F4xx/drivers/rng.c',
                  'platform/mcu/STM32F4xx/drivers/i2c_stm32.c',
                  'platform/mcu/STM32F4xx/drivers/spi_stm32.c',
+                 'platform/mcu/STM32F4xx/drivers/adc_stm32.c',
                  'platform/drivers/audio/stm32_dac.cpp',
                  'platform/drivers/audio/stm32_adc.cpp',
                  'platform/drivers/audio/stm32_pwm.cpp',

platform/mcu/STM32F4xx/drivers/adc_stm32.c

@@ -0,0 +1,116 @@
+/***************************************************************************
+ *   Copyright (C) 2020 - 2023 by Silvano Seva IU2KWO                      *
+ *                            and Niccolò Izzo IU2KIN                      *
+ *                                                                         *
+ *   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 <stm32f4xx.h>
+#include <pthread.h>
+#include <errno.h>
+#include "adc_stm32.h"
+
+int adcStm32_init(const struct Adc *adc)
+{
+    switch((uint32_t) adc->priv)
+    {
+        case ADC1_BASE:
+            RCC->APB2ENR |= RCC_APB2ENR_ADC1EN;
+            __DSB();
+            break;
+
+        case ADC2_BASE:
+            RCC->APB2ENR |= RCC_APB2ENR_ADC2EN;
+            __DSB();
+            break;
+
+        case ADC3_BASE:
+            RCC->APB2ENR |= RCC_APB2ENR_ADC3EN;
+            __DSB();
+            break;
+
+        default:
+            return -EINVAL;
+            break;
+    }
+
+    ADC_TypeDef *pAdc = ((ADC_TypeDef *) adc->priv);
+
+    /*
+     * ADC clock is APB2 frequency divided by 8, giving 10.5MHz.
+     * We set the sample time of each channel to 84 ADC cycles and we have that
+     * a conversion takes 12 cycles: total conversion time is then of ~9us.
+     */
+    ADC->CCR   |= ADC_CCR_ADCPRE;
+    pAdc->SMPR2 = 0x4924924;
+    pAdc->SMPR1 = 0x24924924;
+
+    /*
+     * Convert one channel, no overrun interrupt, 12-bit resolution,
+     * no analog watchdog, discontinuous mode, no end of conversion interrupts,
+     * turn on ADC.
+     */
+    pAdc->SQR1 = 0;
+    pAdc->CR2  = ADC_CR2_ADON;
+
+    if(adc->mutex != NULL)
+        pthread_mutex_init((pthread_mutex_t *) adc->mutex, NULL);
+
+    return 0;
+}
+
+void adcStm32_terminate(const struct Adc *adc)
+{
+    /* A conversion may be in progress, wait until it finishes */
+    if(adc->mutex != NULL)
+        pthread_mutex_lock((pthread_mutex_t *) adc->mutex);
+
+    ((ADC_TypeDef *) adc->priv)->CR2 = 0;
+
+    switch((uint32_t) adc->priv)
+    {
+        case ADC1_BASE:
+            RCC->APB2ENR &= ~RCC_APB2ENR_ADC1EN;
+            __DSB();
+            break;
+
+        case ADC2_BASE:
+            RCC->APB2ENR &= ~RCC_APB2ENR_ADC2EN;
+            __DSB();
+            break;
+
+        case ADC3_BASE:
+            RCC->APB2ENR &= ~RCC_APB2ENR_ADC3EN;
+            __DSB();
+            break;
+    }
+
+    if(adc->mutex != NULL)
+        pthread_mutex_destroy((pthread_mutex_t *) adc->mutex);
+}
+
+uint16_t adcStm32_sample(const struct Adc *adc, const uint32_t channel)
+{
+    if(channel > 19)
+        return 0;
+
+    ADC_TypeDef *pAdc = ((ADC_TypeDef *) adc->priv);
+
+    pAdc->SQR3 = channel;
+    pAdc->CR2 |= ADC_CR2_SWSTART;
+
+    while((pAdc->SR & ADC_SR_EOC) == 0) ;
+
+    return pAdc->DR;
+}

platform/mcu/STM32F4xx/drivers/adc_stm32.h

@@ -0,0 +1,66 @@
+/***************************************************************************
+ *   Copyright (C) 2024 by 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 ADC_STM32_H
+#define ADC_STM32_H
+
+#include <peripherals/adc.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/**
+ * Define an instance of an STM32 ADC device driver.
+ *
+ * @param name: instance name.
+ * @param periph: pointer to hardware peripheral.
+ * @param mutx: pointer to mutex for concurrent access, can be NULL.
+ * @param vref: ADC reference voltage, in uV.
+ */
+#define ADC_STM32_DEVICE_DEFINE(name, periph, mutx, vref) \
+extern uint16_t adcStm32_sample(const struct Adc *adc,    \
+                                const uint32_t channel);  \
+const struct Adc name =                                   \
+{                                                         \
+    .sample     = &adcStm32_sample,                       \
+    .priv       = periph,                                 \
+    .mutex      = mutx,                                   \
+    .countsTouV = ADC_COUNTS_TO_UV(vref, 12)              \
+};
+
+/**
+ * Initialize an STM32 ADC peripheral.
+ *
+ * @param adc: pointer to ADC device handle.
+ * @return zero on success, a negative error code otherwise.
+ */
+int adcStm32_init(const struct Adc *adc);
+
+/**
+ * Shut down an STM32 ADC peripheral.
+ *
+ * @param adc: pointer to ADC device handle.
+ * @return zero on success, a negative error code otherwise.
+ */
+void adcStm32_terminate(const struct Adc *adc);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ADC_STM32_H */