Basic DAC Driver, implementation on stm32f4discovery

boards/stm32f4discovery/Makefile.features

@@ -1,2 +1 @@
-FEATURES_PROVIDED += periph_gpio periph_spi periph_i2c periph_pwm periph_random periph_adc cpp
-
+FEATURES_PROVIDED += periph_gpio periph_spi periph_i2c periph_pwm periph_random periph_adc periph_dac cpp

boards/stm32f4discovery/include/periph_conf.h

@@ -132,21 +132,41 @@ extern "C" {
 #define ADC_0_CH1           4
 #define ADC_0_CH1_PIN       4
 
-/* ADC 0 configuration */
+/* ADC 1 configuration */
 #define ADC_1_DEV           ADC2
 #define ADC_1_CHANNELS      2
 #define ADC_1_CLKEN()       (RCC->APB2ENR |= RCC_APB2ENR_ADC2EN)
 #define ADC_1_CLKDIS()      (RCC->APB2ENR &= ~(RCC_APB2ENR_ADC2EN))
+
 #define ADC_1_PORT          GPIOC
 #define ADC_1_PORT_CLKEN()  (RCC->AHB1ENR |= RCC_AHB1ENR_GPIOCEN)
-/* ADC 0 channel 0 pin config */
+/* ADC 1 channel 0 pin config */
 #define ADC_1_CH0           11
 #define ADC_1_CH0_PIN       1
-/* ADC 0 channel 1 pin config */
+/* ADC 1 channel 1 pin config */
 #define ADC_1_CH1           12
 #define ADC_1_CH1_PIN       2
 /** @} */
 
+/**
+ * @name DAC configuration
+ * @{
+ */
+#define DAC_NUMOF          (1U)
+#define DAC_0_EN           1
+#define DAC_MAX_CHANNELS   2
+
+/* DAC 0 configuration */
+#define DAC_0_DEV            DAC
+#define DAC_0_CHANNELS       2
+#define DAC_0_CLKEN()        (RCC->APB1ENR |=  (RCC_APB1ENR_DACEN))
+#define DAC_0_CLKDIS()       (RCC->APB1ENR &= ~(RCC_APB1ENR_DACEN))
+#define DAC_0_PORT           GPIOA
+#define DAC_0_PORT_CLKEN()   (RCC->AHB1ENR |= RCC_AHB1ENR_GPIOAEN)     
+/* DAC 0 channel config */
+#define DAC_0_CH0_PIN        4
+#define DAC_0_CH1_PIN        5
+
 /**
  * @name PWM configuration
  * @{

cpu/stm32f4/periph/dac.c

@@ -0,0 +1,166 @@
+/*
+ * Copyright (C) 2014 Simon Brummer
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser General
+ * Public License v2.1. See the file LICENSE in the top level directory for more
+ * details.
+ */
+
+/**
+ * @ingroup     cpu_stm32f4
+ * @{
+ *
+ * @file
+ * @brief       Low-level DAC driver implementation
+ *
+ * @author      Simon Brummer<simon.brummer@haw-hamburg.de>
+ *
+ * @}
+ */
+
+#include "cpu.h"
+#include "periph/dac.h"
+#include "periph_conf.h"
+
+/* guard in case that no DAC device is defined */
+#if DAC_NUMOF
+
+#define DAC_MAX_12BIT 0x0fff
+
+typedef struct {
+    uint8_t shift_mod;
+} dac_config_t;
+
+dac_config_t dac_config[DAC_NUMOF];
+
+int8_t dac_init(dac_t dev, dac_precision_t precision)
+{
+    DAC_TypeDef *dac = 0;
+    dac_poweron(dev);
+
+    switch (dev) {
+#if DAC_0_EN
+        case DAC_0:
+            dac = DAC_0_DEV;
+            DAC_0_PORT_CLKEN();
+            /* Set Mode to analoge out, disable Pullup Pulldown Resistors for both channels */
+            DAC_0_PORT->MODER |=  (3 << (DAC_0_CH0_PIN * 2) | 3 << (DAC_0_CH1_PIN * 2));
+            DAC_0_PORT->PUPDR &= ~(3 << (DAC_0_CH0_PIN * 2) | 3 << (DAC_0_CH1_PIN * 2));
+            break;
+#endif
+        default:
+            /* Unknown Device */
+            return -1;
+    }
+
+    /* Select Shift value to normalize given Value */
+    switch(precision) {
+        case DAC_RES_6BIT:
+            dac_config[dev].shift_mod = 0x06;       /* 2^6  << 6 = 2^12 */
+            break;
+        case DAC_RES_8BIT:
+            dac_config[dev].shift_mod = 0x04;       /* 2^8  << 4 = 2^12 */
+            break;
+        case DAC_RES_10BIT:
+            dac_config[dev].shift_mod = 0x02;       /* 2^10 << 2 = 2^12 */
+            break;
+        case DAC_RES_12BIT:
+            dac_config[dev].shift_mod = 0x00;       /* 2^12 << 0 = 2^12 */
+            break;
+        /* Not Supported Resolutions */
+        case DAC_RES_14BIT:
+        case DAC_RES_16BIT:
+        default:
+            dac_poweroff(dev);
+            return -2;
+        break;
+    }
+
+    /* Enable Channels, Clear Output */
+    dac->CR = 0;
+    dac->CR |= (DAC_CR_EN1 | DAC_CR_EN2);
+    dac->DHR12R1 = 0;
+    dac->DHR12R2 = 0;
+
+    return 0;
+}
+
+int8_t dac_write(dac_t dev, uint8_t channel, uint16_t value)
+{
+    DAC_TypeDef* __attribute__((unused))  dac = 0;
+    uint16_t     __attribute__((unused))  val = value << dac_config[dev].shift_mod;
+
+    switch(dev){
+#if DAC_0_EN
+    case DAC_0:
+        dac = DAC_0_DEV;
+
+        if( DAC_MAX_12BIT < val ){
+            /* Value out of Range */
+            return -3;
+        }
+
+        switch(channel){
+            case 0:
+                dac->DHR12R1 = val;
+                break;
+            case 1:
+                dac->DHR12R2 = val;
+                break;
+            /* Invalid Channel */
+            default:
+                return -2;
+        }
+        break;
+#endif
+        /* Unknown  Device */
+        default:
+            return -1;
+    }
+    return 0;
+}
+
+int8_t dac_poweron(dac_t dev)
+{
+    switch (dev){
+#if DAC_0_EN
+        case DAC_0:
+            DAC_0_CLKEN();
+            break;
+#endif
+        default:
+            /* Unknown Device */
+            return -1;
+    }
+    return 0;
+}
+
+int8_t dac_poweroff(dac_t dev)
+{
+    switch (dev) {
+#if DAC_0_EN
+        case DAC_0:
+            DAC_0_CLKDIS();
+            break;
+#endif
+        default:
+            /* Unknown Device */
+            return -1;
+    }
+    return 0;
+}
+
+uint16_t dac_map(dac_t dev, int value, int min, int max)
+{
+    return dac_mapf(dev, (int) value, (int) min, (int) max);
+}
+
+uint16_t dac_mapf(dac_t dev, float value, float min, float max)
+{
+    uint16_t val_12_bit = ((value - min) * DAC_MAX_12BIT)/(max-min);
+    return val_12_bit >> dac_config[dev].shift_mod;
+}
+
+#undef DAC_MAX_12BIT
+
+#endif /* DAC_NUMOF */

drivers/include/periph/dac.h

@@ -0,0 +1,152 @@
+/*
+ * Copyright (C) 2014 Simon Brummer
+ *
+ * This file is subject to the terms and conditions of the GNU Lesser
+ * General Public License v2.1. See the file LICENSE in the top level
+ * directory for more details.
+ */
+
+/**
+ * @defgroup    driver_periph_dac DAC
+ * @ingroup     driver_periph
+ * @brief       Low-level DAC peripheral driver
+ * @{
+ *
+ * @file
+ * @brief       Low-level DAC peripheral driver interface definitions
+ *
+ * @author      Simon Brummer <simon.brummer@haw-hamburg.de>
+ */
+
+#ifndef __DAC_H
+#define __DAC_H
+
+#include <stdint.h>
+#include "periph_conf.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+/* guard file in case no ADC device is defined */
+#if DAC_NUMOF
+
+/**
+  * @brief Definition avialable DAC devices
+  *
+  * Each DAC device is based on a hardware DAC which can have one or more
+  * independet channels.
+  */
+typedef enum {
+#if DAC_0_EN
+    DAC_0 = 0,             /**< DAC device 0 */
+#endif
+#if DAC_1_EN
+    DAC_1 = 1,             /**< DAC device 1 */
+#endif
+#if DAC_2_EN
+    DAC_2 = 2,             /**< DAC device 2 */
+#endif
+#if DAC_3_EN
+    DAC_3 = 3,             /**< DAC device 3 */
+#endif
+} dac_t;
+
+/**
+ * @breif Possilbe DAC precision settings
+ */
+typedef enum {
+    DAC_RES_6BIT = 0,      /**< DAC precision: 6 bit */
+    DAC_RES_8BIT,          /**< DAC precision: 8 bit */
+    DAC_RES_10BIT,         /**< DAC precision: 10 bit */
+    DAC_RES_12BIT,         /**< DAC precision: 12 bit */
+    DAC_RES_14BIT,         /**< DAC precision: 14 bit */
+    DAC_RES_16BIT,         /**< DAC precision: 16 bit */
+} dac_precision_t;
+
+/**
+ * @brief Initialization of a given DAC device
+ *
+ * The DAC will be initialized with all possilble channels active. 
+ * On each channel will be initialized with a Zero on it.
+ *
+ * @param[in] dev          the device to initialize
+ * @param[in] precision    the precision to use for conversion
+ *
+ * @return                 0 on success
+ * @return                 -1 on unknown DAC Device
+ * @return                 -2 on precision not available
+ */
+int8_t dac_init(dac_t dev, dac_precision_t precision);
+
+/**
+ * @brief Write a value onto DAC Device on a given Channel.
+ *
+ * @param[in] dev          the DAC device to use
+ * @param[in] channel      the channel used for Digital/Analoge conversion 
+ * @param[in] value        the value to write onto DAC. 
+ * 
+ * @return                 0 on success
+ * @return                 -1 on unknown DAC Device
+ * @return                 -2 on invalid channel 
+ * @return                 -3 if value is out of range. 
+ */
+int8_t dac_write(dac_t dev, uint8_t channel, uint16_t value);
+
+/**
+ * @brief Enable power for the given DAC Device
+ * 
+ * @param[in] dev          the DAC device to power up.
+ *
+ * @return                 0 on success
+ * @return                 -1 on unknown DAC Device
+ */
+int8_t dac_poweron(dac_t dev);
+
+/**
+ * @brief Disable power for the given DAC Device
+ *
+ * @param[in] dev          the DAC device to power down
+ * 
+ * @return                 0 on success
+ * @return                 -1 on unknown DAC Device
+ */
+int8_t dac_poweroff(dac_t dev);
+
+/**
+ * @brief Helper function to map a given integer range to a valid DAC value.
+ * 
+ * This function is useful for converting ranges of values to a valid DAC output value.
+ *
+ * The min value is assumed to be smaller than max value and value is assumed 
+ * to be between min and max.
+ *
+ * @param[in] dev          the DAC Device to read precision value from
+ * @param[in] value        the value to map onto min and max
+ * @param[in] min          the lower bound of the target interval
+ * @param[in] max          the upper bound of the target interval
+ *
+ * @return                 the mapped value, in valid DAC range
+ */
+uint16_t dac_map(dac_t dev, int value, int min, int max);
+
+/**
+ * @brief Helper function to map a given float value range to a valid DAC value.
+ * 
+ * @see dac_map
+ *
+ * @param[in] dev          the DAC Device to read precision value from
+ * @param[in] value        the value to map onto min and max
+ * @param[in] min          the lower bound of the target interval
+ * @param[in] max          the upper bound of the target interval
+ * 
+ * @return                 the mapped value, in valid DAC range
+ */
+uint16_t dac_mapf(dac_t dev, float value, float min, float max);
+
+#endif/* DAC_NUMOF */ 
+#ifdef __cplusplus
+}
+#endif
+#endif /* __DAC_H */
+/** @} */