Diff: targets/TARGET_Silicon_Labs/TARGET_EFM32/analogin_api.c

Revision:

149:156823d33999

Parent:

144:ef7eb2e8f9f7

Child:

176:447f873cad2f

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/targets/TARGET_Silicon_Labs/TARGET_EFM32/analogin_api.c	Fri Oct 28 11:17:30 2016 +0100
@@ -0,0 +1,106 @@
+/***************************************************************************//**
+ * @file analogin_api.c
+ *******************************************************************************
+ * @section License
+ * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
+ *******************************************************************************
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ ******************************************************************************/
+
+#include "device.h"
+#if DEVICE_ANALOGIN
+
+#include "mbed_assert.h"
+#include "analogin_api.h"
+
+#include "pinmap.h"
+#include "pinmap_function.h"
+#include "PeripheralPins.h"
+
+#include "em_adc.h"
+#include "em_cmu.h"
+
+void analogin_init(analogin_t *obj, PinName pin)
+{
+    static uint8_t adc_initialized = 0;
+
+    /* Init structure */
+    obj->adc = (ADC_TypeDef *) pinmap_peripheral(pin, PinMap_ADC);
+    MBED_ASSERT((int) obj->adc != NC);
+
+    obj->channel = pin_location(pin, PinMap_ADC);
+    MBED_ASSERT((int) obj->channel != NC);
+
+    /* Only initialize the ADC once */
+    if (!adc_initialized) {
+        /* Turn on the clock */
+        CMU_ClockEnable(cmuClock_ADC0, true);
+
+        /* Init with default settings */
+        ADC_Init_TypeDef init = ADC_INIT_DEFAULT;
+        init.prescale = 4;
+        ADC_Init(obj->adc, &init);
+
+        /* Init for single conversion use */
+        ADC_InitSingle_TypeDef singleInit = ADC_INITSINGLE_DEFAULT;
+
+        /* Measure input channel with Vdd reference. */
+        singleInit.reference = adcRefVDD;
+        singleInit.resolution = adcRes12Bit;
+        singleInit.acqTime = adcAcqTime32;
+
+        ADC_InitSingle(obj->adc, &singleInit);
+
+        adc_initialized = 1;
+    }
+}
+
+uint16_t analogin_read_u16(analogin_t *obj)
+{
+    ADC_TypeDef *adc = obj->adc;
+    uint16_t sample = 0;
+
+    //Make sure a single conversion is not in progress
+    adc->CMD = ADC_CMD_SINGLESTOP;
+
+    // Make sure we are checking the correct channel
+#if defined _ADC_SINGLECTRL_INPUTSEL_MASK
+    adc->SINGLECTRL = (adc->SINGLECTRL & ~_ADC_SINGLECTRL_INPUTSEL_MASK) | obj->channel;
+#elif _ADC_SINGLECTRL_POSSEL_MASK
+    adc->SINGLECTRL = (adc->SINGLECTRL & ~_ADC_SINGLECTRL_POSSEL_MASK) | obj->channel << _ADC_SINGLECTRL_POSSEL_SHIFT;
+#endif
+
+    ADC_Start(adc, adcStartSingle);
+
+    /* Wait while conversion is active */
+    while (adc->STATUS & ADC_STATUS_SINGLEACT);
+
+    /* Get ADC result */
+    sample = ADC_DataSingleGet(adc);
+
+    /* The ADC has 12 bit resolution. We shift in 4 0s */
+    /* from the right to make it a 16 bit number as expected */
+    return sample << 4;
+}
+
+float analogin_read(analogin_t *obj)
+{
+    /* Convert from a uint16 to a float between 0 and 1 by division by 0xFFFF */
+    return analogin_read_u16(obj) / (float) 0xFFFF;
+}
+
+#endif