Standard interface for ADC peripherals

openrtx/include/peripherals/adc.h

@@ -0,0 +1,97 @@
+/***************************************************************************
+ *   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_H
+#define ADC_H
+
+#include <pthread.h>
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+struct Adc;
+
+/**
+ * Sample one ADC channel returning the raw converted value.
+ *
+ * @param adc: pointer to ADC device handle.
+ * @param channel: channel number.
+ * @return channel raw value, zero if channel is out of range.
+ */
+typedef uint16_t (*adc_sample_impl)(const struct Adc *adc, const uint32_t channel);
+
+/**
+ * ADC device handle.
+ */
+struct Adc
+{
+    const adc_sample_impl sample;      ///< Device-specific implementation of the ADC sample function
+    const void            *priv;       ///< Pointer to device driver private data
+    const pthread_mutex_t *mutex;      ///< Pointer to mutex, can be NULL
+    const uint32_t        countsTouV;  ///< Conversion factor from counts to uV
+};
+
+/**
+ * Compute conversion factor from ADC counts to uV expressed in Q16.16 format.
+ *
+ * @param vref: ADC reference voltage, in uV.
+ * @param resolution: ADC resolution, in bits.
+ * @return conversion factor.
+ */
+#define ADC_COUNTS_TO_UV(vref, resolution) (vref << (16 - resolution))
+
+/**
+ * Sample one ADC channel returning the raw converted value.
+ *
+ * @param adc: pointer to ADC device handle.
+ * @param channel: channel number.
+ * @return channel raw value, zero if channel is out of range.
+ */
+static inline uint16_t adc_getRawSample(const struct Adc *adc, const uint32_t channel)
+{
+    if(adc->mutex != NULL)
+        pthread_mutex_lock((pthread_mutex_t *) adc->mutex);
+
+    uint16_t sample = adc->sample(adc, channel);
+
+    if(adc->mutex != NULL)
+        pthread_mutex_unlock((pthread_mutex_t *) adc->mutex);
+
+    return sample;
+}
+
+/**
+ * Sample one ADC channel returning the voltage, in uV.
+ *
+ * @param adc: pointer to ADC device handle.
+ * @param channel: channel number.
+ * @return channel voltage, zero if channel is out of range.
+ */
+static inline uint32_t adc_getVoltage(const struct Adc *adc, const uint32_t channel)
+{
+    uint64_t value = adc_getRawSample(adc, channel);
+    return (value * adc->countsTouV) >> 16;
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* ADC_H */