Merge pull request #616 from haukepetersen/periph_driver_adc

Initial import of low-level ADC driver interface

drivers/include/periph/adc.h

@@ -0,0 +1,105 @@
+/*
+ * Copyright (C) 2014 Freie Universität Berlin
+ *
+ * This file is subject to the terms and conditions of the LGPLv2 License.
+ * See the file LICENSE in the top level directory for more details.
+ */
+
+/**
+ * @ingroup     driver_periph
+ * @brief       Low-level ADC peripheral driver
+ * @{
+ *
+ * @file        adc.h
+ * @brief       Low-level ADC peripheral driver interface definitions
+ *
+ * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
+ */
+
+#ifndef __ADC_H
+#define __ADC_H
+
+#include "periph_conf.h"
+
+
+/**
+ * @brief Definition available ADC devices
+ * 
+ * Each ADC device is based on a hardware ADC which can have one or more
+ * multiplexed channels.
+ */
+typedef enum {
+#if ADC_0_EN
+    ADC_0,              /*< ADC device 0 */
+#endif
+#if ADC_1_EN
+    ADC_1,              /*< ADC device 1 */
+#endif
+#if ADC_2_EN
+    ADC_2,               /*< ADC device 2 */
+#endif
+#if ADC_3_EN
+    ADC_3,               /*< ADC device 3 */
+#endif
+    ADC_UNDEFINED
+} adc_t;
+
+/**
+ * @brief Initialization of a given ADC device
+ * 
+ * The ADC will be initialized in synchronous, blocking mode, so no callbacks for finished
+ * conversions are required as conversions are presumed to be very fast (somewhere in the
+ * range of some us).
+ *
+ * @param[in] dev           the device to initialize
+ * @param[in] precision     the conversion precision in bits, will LSBs will be stuffed if
+ *                          precision > max precision of hardware
+ *
+ * @return                  1 on success, -1 on error
+ */
+int adc_init(adc_t dev, int precision);
+
+/**
+ * @brief Start a new conversion by using the given channel.
+ * 
+ * If a conversion on any channel on the given ADC core is in progress, it is aborted.
+ * 
+ * @param[in] dev           the ADC device to use for the conversion
+ * @param[in] channel       the channel to convert from
+ *
+ * @return                  the converted value with the defined precision, -1 on error
+ */
+int adc_sample(adc_t dev, int channel);
+
+/**
+ * @brief Helper function to map a converted value to the given integer range.
+ * 
+ * This function is useful for converting sampled ADC values into their physical representation.
+ * 
+ * The min value is asserted to be smaller than the max value.
+ * 
+ * @param[in] dev           the ADC device to read the precision value from (as input interval)
+ * @param[in] value         the value to map
+ * @param[in] min           the lower bound of the target interval
+ * @param[in] max           the upper bound of the target interval
+ *
+ * @return                  the mapped value
+ */
+int adc_map(adc_t dev, int value, int min, int max);
+
+/**
+ * @brief Helper function to map a converted value to the given float range
+ * 
+ * @see adc_map
+ * 
+ * @param[in] dev           the ADC device to read the precision value from (as input interval)
+ * @param[in] value         the value to map
+ * @param[in] min           the lower bound of the target interval
+ * @param[in] max           the upper bound of the target interval
+ *
+ * @return                  the mapped value
+ */
+float adc_mapf(adc_t dev, int value, float min, float max);
+
+#endif /* __ADC_H */
+/** @} */