cpu/stm32f4: reworked the ADC driver

cpu/stm32f4/include/periph_cpu.h

@@ -25,6 +25,15 @@
 extern "C" {
 #endif
 
+/**
+ * @brief   Available number of ADC devices
+ */
+#if defined(CPU_MODEL_STM32F401RE)
+#define ADC_DEVS            (1U)
+#elif defined(CPU_MODEL_STM32F407VG) || defined(CPU_MODEL_STM32F415RG)
+#define ADC_DEVS            (3U)
+#endif
+
 /**
  * @brief   Overwrite the default gpio_t type definition
  * @{
@@ -43,6 +52,30 @@ typedef uint32_t gpio_t;
  */
 #define GPIO_PIN(x, y)      ((GPIOA_BASE + (x << 10)) | y)
 
+/**
+ * @brief declare needed generic SPI functions
+ * @{
+ */
+#define PERIPH_SPI_NEEDS_TRANSFER_BYTES
+#define PERIPH_SPI_NEEDS_TRANSFER_REG
+#define PERIPH_SPI_NEEDS_TRANSFER_REGS
+/** @} */
+
+/**
+ * @brief   Override the ADC resolution configuration
+ * @{
+ */
+#define HAVE_ADC_RES_T
+typedef enum {
+    ADC_RES_6BIT  = 0x03000000,  /**< ADC resolution: 6 bit */
+    ADC_RES_8BIT  = 0x02000000,  /**< ADC resolution: 8 bit */
+    ADC_RES_10BIT = 0x01000000,  /**< ADC resolution: 10 bit */
+    ADC_RES_12BIT = 0x00000000,  /**< ADC resolution: 12 bit */
+    ADC_RES_14BIT = 1,           /**< ADC resolution: 14 bit (not supported) */
+    ADC_RES_16BIT = 2            /**< ADC resolution: 16 bit (not supported)*/
+} adc_res_t;
+/** @} */
+
 /**
  * @brief   Available ports on the STM32F4 family
  */
@@ -95,6 +128,16 @@ typedef struct {
 } uart_conf_t;
 /** @} */
 
+/**
+ * @brief   ADC channel configuration data
+ */
+typedef struct {
+    gpio_t pin;             /**< pin connected to the channel */
+    uint8_t dev;            /**< ADCx - 1 device used for the channel */
+    uint8_t chan;           /**< CPU ADC channel connected to the pin */
+    uint8_t rcc;            /**< bit in the RCC APB2 enable register */
+} adc_conf_t;
+
 /**
  * @brief   Configure the alternate function for the given pin
  *
@@ -105,6 +148,13 @@ typedef struct {
  */
 void gpio_init_af(gpio_t pin, gpio_af_t af);
 
+/**
+ * @brief   Configure the given pin to be used as ADC input
+ *
+ * @param[in] pin       pin to configure
+ */
+void gpio_init_analog(gpio_t pin);
+
 /**
  * @brief   Power on the DMA device the given stream belongs to
  *

cpu/stm32f4/periph/adc.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2014 Freie Universität Berlin
+ * Copyright (C) 2014-2016 Freie Universität Berlin
  *
  * 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
@@ -19,167 +19,111 @@
  */
 
 #include "cpu.h"
+#include "mutex.h"
 #include "periph/adc.h"
 #include "periph_conf.h"
 
-/* guard in case that no ADC device is defined */
+/**
-#if ADC_NUMOF
+ * @brief   Maximum allowed ADC clock speed
+ */
+#define MAX_ADC_SPEED           (12000000U)
 
-typedef struct {
+/**
-    int max_value;
+ * @brief   Load the ADC configuration
-} adc_config_t;
+ * @{
+ */
+#ifdef ADC_CONFIG
+static const adc_conf_t adc_config[] = ADC_CONFIG;
+#else
+static const adc_conf_t adc_config[] = {};
+#endif
 
-adc_config_t adc_config[ADC_NUMOF];
+/**
+ * @brief   Allocate locks for all three available ADC devices
+ */
+static mutex_t locks[] = {
+#if ADC_DEVS > 1
+    MUTEX_INIT,
+#endif
+#if ADC_DEVS > 2
+    MUTEX_INIT,
+#endif
+    MUTEX_INIT
+};
 
-int adc_init(adc_t dev, adc_precision_t precision)
+static inline ADC_TypeDef *dev(adc_t line)
 {
-    ADC_TypeDef *adc = 0;
+    return (ADC_TypeDef *)(ADC1_BASE + (adc_config[line].dev << 8));
+}
 
-    adc_poweron(dev);
+static inline void prep(adc_t line)
+{
+    mutex_lock(&locks[adc_config[line].dev]);
+    RCC->APB2ENR |= (RCC_APB2ENR_ADC1EN << adc_config[line].dev);
+}
 
-    switch (dev) {
+static inline void done(adc_t line)
-#if ADC_0_EN
+{
-        case ADC_0:
+    RCC->APB2ENR &= ~(RCC_APB2ENR_ADC1EN << adc_config[line].dev);
-            adc = ADC_0_DEV;
+    mutex_unlock(&locks[adc_config[line].dev]);
-            ADC_0_PORT_CLKEN();
+}
-            ADC_0_PORT->MODER |= (3 << (ADC_0_CH0_PIN * 2) | 3 << (ADC_0_CH1_PIN * 2));
+
-            break;
+int adc_init(adc_t line)
-#endif
+{
-#if ADC_1_EN
+    uint32_t clk_div = 2;
-        case ADC_1:
+
-            adc = ADC_1_DEV;
+    /* check if the line is valid */
-            ADC_1_PORT_CLKEN();
+    if (line >= ADC_NUMOF) {
-            ADC_1_PORT->MODER |= (3 << (ADC_1_CH0_PIN * 2) | 3 << (ADC_1_CH1_PIN * 2));
-            break;
-#endif
-        default:
         return -1;
     }
 
-    /* reset control registers */
+    /* lock and power-on the device */
-    adc->CR1 = 0;
+    prep(line);
-    adc->CR2 = 0;
-    adc->SQR1 = 0;
 
-    /* set precision */
+    /* configure the pin */
-
+    gpio_init_analog(adc_config[line].pin);
-    switch (precision) {
+    /* set sequence length to 1 conversion and enable the ADC device */
-        case ADC_RES_6BIT:
+    dev(line)->SQR1 = 0;
-            adc->CR1 |= ADC_CR1_RES_0 | ADC_CR1_RES_1;
+    dev(line)->CR2 = ADC_CR2_ADON;
-            adc_config[dev].max_value = 0x3f;
+    /* set clock prescaler to get the maximal possible ADC clock value */
-            break;
+    for (clk_div = 2; clk_div < 8; clk_div += 2) {
-        case ADC_RES_8BIT:
+        if ((CLOCK_CORECLOCK / clk_div) <= MAX_ADC_SPEED) {
-            adc->CR1 |= ADC_CR1_RES_1;
-            adc_config[dev].max_value = 0xff;
-            break;
-        case ADC_RES_10BIT:
-            adc->CR1 |= ADC_CR1_RES_0;
-            adc_config[dev].max_value = 0x3ff;
-            break;
-        case ADC_RES_12BIT:
-            adc_config[dev].max_value = 0xfff;
-            break;
-        case ADC_RES_14BIT:
-        case ADC_RES_16BIT:
-            adc_poweroff(dev);
-            return -1;
             break;
         }
+    }
+    ADC->CCR = ((clk_div / 2) - 1) << 16;
 
-    /* set clock prescaler */
+    /* free the device again */
-    ADC->CCR = (3 << 16);       /* ADC clock = 10,5MHz */
+    done(line);
-
-    /* enable the ADC module */
-    adc->CR2 |= ADC_CR2_ADON;
-
     return 0;
 }
 
-int adc_sample(adc_t dev, int channel)
+int adc_sample(adc_t line, adc_res_t res)
 {
-    ADC_TypeDef *adc = 0;
+    int sample;
 
-    switch (dev) {
+    /* check if resolution is applicable */
-#if ADC_0_EN
+    if (res < 0xff) {
-        case ADC_0:
-            adc = ADC_0_DEV;
-            switch (channel) {
-                case 0:
-                    adc->SQR3 = ADC_0_CH0 & 0x1f;
-                    break;
-                case 1:
-                    adc->SQR3 = ADC_0_CH1 & 0x1f;
-                    break;
-                default:
         return -1;
     }
-            break;
-#endif
-#if ADC_1_EN
-        case ADC_1:
-            adc = ADC_1_DEV;
-            switch (channel) {
-                case 0:
-                    adc->SQR3 = ADC_1_CH0 & 0x1f;
-                    break;
-                case 1:
-                    adc->SQR3 = ADC_1_CH1 & 0x1f;
-                    break;
-                default:
-                    return -1;
-            }
-            break;
-#endif
-    }
 
-    /* start single conversion */
+    /* lock and power on the ADC device  */
-    adc->CR2 |= ADC_CR2_SWSTART;
+    prep(line);
-    /* wait until conversion is complete */
-    while (!(adc->SR & ADC_SR_EOC)) {}
-    /* read and return result */
-    return (int)adc->DR;
-}
 
-void adc_poweron(adc_t dev)
+    /* wait for any ongoing conversions to finish */
-{
+    while (dev(line)->SR & ADC_SR_STRT) {}
-    switch (dev) {
+    /* set resolution and conversion channel */
-#if ADC_0_EN
+    dev(line)->CR1 = res;
-        case ADC_0:
+    dev(line)->SQR3 = adc_config[line].chan;
-            ADC_0_CLKEN();
+    /* start conversion and wait for results */
-            break;
+    dev(line)->CR2 |= ADC_CR2_SWSTART;
-#endif
+    while (!(dev(line)->SR & ADC_SR_EOC)) {}
-#if ADC_1_EN
+    /* finally read sample and reset the STRT bit in the status register */
-        case ADC_1:
+    sample = (int)dev(line)->DR;
-            ADC_1_CLKEN();
+    dev(line)->SR &= ~ADC_SR_STRT;
-            break;
-#endif
-    }
-}
 
-void adc_poweroff(adc_t dev)
+    /* power off and unlock device again */
-{
+    done(line);
-    switch (dev) {
-#if ADC_0_EN
-        case ADC_0:
-            ADC_0_CLKDIS();
-            break;
-#endif
-#if ADC_1_EN
-        case ADC_1:
-            ADC_1_CLKDIS();
-            break;
-#endif
-    }
-}
 
-int adc_map(adc_t dev, int value, int min, int max)
+    return sample;
-{
-    return (int)adc_mapf(dev, value, (float)min, (float)max);
 }
-
-float adc_mapf(adc_t dev, int value, float min, float max)
-{
-    return ((max - min) / ((float)adc_config[dev].max_value)) * value;
-}
-
-#endif /* ADC_NUMOF */

cpu/stm32f4/periph/gpio.c

@@ -148,6 +148,14 @@ void gpio_init_af(gpio_t pin, gpio_af_t af)
     port->AFR[(pin_num > 7) ? 1 : 0] |= (af << ((pin_num & 0x07) * 4));
 }
 
+void gpio_init_analog(gpio_t pin)
+{
+    /* enable clock */
+    RCC->AHB1ENR |= (RCC_AHB1ENR_GPIOAEN << _port_num(pin));
+    /* set to analog mode */
+    _port(pin)->MODER |= (0x3 << (2 * _pin_num(pin)));
+}
+
 void gpio_irq_enable(gpio_t pin)
 {
     EXTI->IMR |= (1 << _pin_num(pin));