cpu/lpc11u34: reworked ADC driver

cpu/lpc11u34/include/periph_cpu.h

@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2015 Freie Universität Berlin
+ * Copyright (C) 2015-2016 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
@@ -14,6 +14,7 @@
  * @brief           CPU specific definitions for internal peripheral handling
  *
  * @author          Paul RATHGEB <paul.rathgeb@skynet.be>
+ * @author          Hauke Petersen<hauke.petersen@fu-berlin.de>
  */
 
 #ifndef PERIPH_CPU_H_
@@ -39,6 +40,28 @@ extern "C" {
  */
 #define CPUID_LEN           (16U)
 
+/**
+ * @brief   Define number of available ADC lines
+ *
+ * TODO: check this value
+ */
+#define ADC_NUMOF           (10U)
+
+/**
+ * @brief   Override the ADC resolution settings
+ * @{
+ */
+#define HAVE_ADC_RES_T
+typedef enum {
+    ADC_RES_6BIT = 0,       /**< ADC resolution: 6 bit */
+    ADC_RES_8BIT,           /**< ADC resolution: 8 bit */
+    ADC_RES_10BIT,          /**< ADC resolution: 10 bit */
+    ADC_RES_12BIT,          /**< ADC resolution: 12 bit */
+    ADC_RES_14BIT,          /**< ADC resolution: 14 bit */
+    ADC_RES_16BIT,          /**< ADC resolution: 16 bit */
+} adc_res_t;
+/** @} */
+
 #ifdef __cplusplus
 }
 #endif

cpu/lpc11u34/periph/adc.c

@@ -1,9 +1,9 @@
 /*
- * Copyright (C) 2015 Freie Universität Berlin
+ * Copyright (C) 2015-2016 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
- * details.
+ * 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.
  */
 
 /**
@@ -13,114 +13,91 @@
  * @file
  * @brief       Low-level ADC driver implementation
  *
- * @author      Paul RATHGEB <paul.rathgeb@skynet.be>
+ * @author      Paul Rathgeb <paul.rathgeb@skynet.be>
+ * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
  *
  * @}
  */
 
 #include <stdint.h>
-#include <string.h>
 
 #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   Mutex to synchronize ADC access from different threads
+ */
+static mutex_t lock = MUTEX_INIT;
 
-static inline uint32_t *_adc_channel_to_pin(int channel)
+static inline uint32_t *pincfg_reg(adc_t line)
 {
-    return (channel < 6) ? ((uint32_t*)(LPC_IOCON) + (11 + channel))
-                         : ((uint32_t*)(LPC_IOCON) + (16 + channel));
+    int offset = (line < 6) ? (11 + line) : (16 + line);
+    return ((uint32_t *)(LPC_IOCON)  + offset);
 }
 
-int adc_init(adc_t dev, adc_precision_t precision)
+static inline void prep(void)
 {
-    adc_poweron(dev);
-
-    /* Set resolution */
-    switch (precision) {
-        case ADC_RES_6BIT:
-            LPC_ADC->CR |= (0x04 << 17);
-            break;
-        case ADC_RES_8BIT:
-            LPC_ADC->CR |= (0x02 << 17);
-            break;
-        case ADC_RES_10BIT:
-            LPC_ADC->CR |= (0x0 << 17);
-            break;
-        case ADC_RES_12BIT:
-        case ADC_RES_14BIT:
-        case ADC_RES_16BIT:
-            /* Resolution > 10 bits unsupported */
-            adc_poweroff(dev);
-            return -1;
-            break;
-    }
-
-    /* ADC frequency : 3MHz */
-    LPC_ADC->CR |= (15 << 8);
+    mutex_lock(&lock);
+    LPC_SYSCON->PDRUNCFG &= ~(1 << 4);
+    LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 13);
+}
 
-    return 0;
+static inline void done(void)
+{
+    LPC_SYSCON->SYSAHBCLKCTRL &= ~(1 << 13);
+    LPC_SYSCON->PDRUNCFG |= (1 << 4);
+    mutex_unlock(&lock);
 }
 
-int adc_sample(adc_t dev, int channel)
+int adc_init(adc_t line)
 {
-    if (channel > ADC_MAX_CHANNELS) {
-        return -1;
-    }
+    uint32_t *pincfg;
+
+    prep();
 
-    /* Compute the IOCON register for the channel */
-    uint32_t *cfg = _adc_channel_to_pin(channel);
+    /* ADC frequency : 3MHz */
+    LPC_ADC->CR = (15 << 8);
+    /* configure the connected pin */
+    pincfg = pincfg_reg(line);
     /* Put the pin in its ADC alternate function */
-    if (channel < 5) {
-        *cfg |= 2;
+    if (line < 5) {
+        *pincfg |= 2;
     }
     else {
-        *cfg |= 1;
+        *pincfg |= 1;
     }
     /* Configure ADMODE in analog input */
-    *cfg &= ~(1 << 7);
-    /* Start a conversion */
-    LPC_ADC->CR |= (1 << channel) | (1 << 24);
-    /* Wait for the end of the conversion */
-    while (!(LPC_ADC->DR[channel] & (1 << 31)));
-    /* Read and return result */
-    return (LPC_ADC->DR[channel] >> 6);
-}
+    *pincfg &= ~(1 << 7);
 
-void adc_poweron(adc_t dev)
-{
-    switch (dev) {
-#if ADC_0_EN
-        case ADC_0:
-            LPC_SYSCON->PDRUNCFG &= ~(1 << 4);
-            LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 13);
-            break;
-#endif
-    }
+    done();
+
+    return 0;
 }
 
-void adc_poweroff(adc_t dev)
+int adc_sample(adc_t line, adc_res_t res)
 {
-    switch (dev) {
-#if ADC_0_EN
-        case ADC_0:
-            LPC_SYSCON->PDRUNCFG |= (1 << 4);
-            LPC_SYSCON->SYSAHBCLKCTRL &= ~(1 << 13);
-            break;
-#endif
+    int sample;
+
+    /* check if resolution is valid */
+    if (res < 0xff) {
+        return -1;
     }
-}
 
-int adc_map(adc_t dev, int value, int min, int max)
-{
-    return 0;
-}
+    /* prepare the device */
+    prep();
 
-float adc_mapf(adc_t dev, int value, float min, float max)
-{
-    return 0.0;
-}
+    /* set resolution */
+    LPC_ADC->CR &= ~(0x7 << 17);
+    LPC_ADC->CR |= res;
+    /* Start a conversion */
+    LPC_ADC->CR |= (1 << line) | (1 << 24);
+    /* Wait for the end of the conversion */
+    while (!(LPC_ADC->DR[line] & (1 << 31))) {}
+    /* Read and return result */
+    sample = (LPC_ADC->DR[line] >> 6);
 
-#endif /* ADC_NUMOF */
+    done();
+
+    return sample;
+}