[NUCLEO_F303RE] Correct ADC initialization

Same as #809

Author: bcostm

libraries/mbed/targets/hal/TARGET_STM/TARGET_NUCLEO_F303RE/analogin_api.c

@@ -37,13 +37,13 @@
 
 ADC_HandleTypeDef AdcHandle;
 
-int adc1_inited = 0;
-int adc2_inited = 0;
-int adc3_inited = 0;
-int adc4_inited = 0;
-
 void analogin_init(analogin_t *obj, PinName pin)
 {
+    static int adc1_inited = 0;
+    static int adc2_inited = 0;
+    static int adc3_inited = 0;
+    static int adc4_inited = 0;
+
     // Get the peripheral name from the pin and assign it to the object
     obj->adc = (ADCName)pinmap_peripheral(pin, PinMap_ADC);
     MBED_ASSERT(obj->adc != (ADCName)NC);
@@ -54,42 +54,49 @@ void analogin_init(analogin_t *obj, PinName pin)
     // Save pin number for the read function
     obj->pin = pin;
 
-    // The ADC initialization is done only once for each ADC
-    if ((adc1_inited == 0) || (adc2_inited == 0) || (adc3_inited == 0) || (adc4_inited == 0)) {
-        if (obj->adc == ADC_1) {
-            __ADC12_CLK_ENABLE();
-            adc1_inited = 1;
-        }
-        if (obj->adc == ADC_2) {
-            __ADC12_CLK_ENABLE();
-            adc2_inited = 1;
-        }
-        if (obj->adc == ADC_3) {
-            __ADC34_CLK_ENABLE();
-            adc3_inited = 1;
-        }
-        if (obj->adc == ADC_4) {
-            __ADC34_CLK_ENABLE();
-            adc4_inited = 1;
-        }
-        // Configure ADC
-        AdcHandle.Instance = (ADC_TypeDef *)(obj->adc);
-        AdcHandle.Init.ClockPrescaler        = ADC_CLOCKPRESCALER_PCLK_DIV2;
-        AdcHandle.Init.Resolution            = ADC_RESOLUTION12b;
-        AdcHandle.Init.DataAlign             = ADC_DATAALIGN_RIGHT;
-        AdcHandle.Init.ScanConvMode          = DISABLE;
-        AdcHandle.Init.EOCSelection          = DISABLE;
-        AdcHandle.Init.LowPowerAutoWait      = DISABLE;
-        AdcHandle.Init.ContinuousConvMode    = DISABLE;
-        AdcHandle.Init.NbrOfConversion       = 1;
-        AdcHandle.Init.DiscontinuousConvMode = DISABLE;
-        AdcHandle.Init.NbrOfDiscConversion   = 0;
-        AdcHandle.Init.ExternalTrigConv      = ADC_EXTERNALTRIGCONV_T1_CC1;
-        AdcHandle.Init.ExternalTrigConvEdge  = ADC_EXTERNALTRIGCONVEDGE_NONE;
-        AdcHandle.Init.DMAContinuousRequests = DISABLE;
-        AdcHandle.Init.Overrun               = OVR_DATA_OVERWRITTEN;
-        HAL_ADC_Init(&AdcHandle);
+    // Check if ADC is already initialized
+    if ((obj->adc == ADC_1) && adc1_inited) return;
+    if ((obj->adc == ADC_2) && adc2_inited) return;
+    if ((obj->adc == ADC_3) && adc3_inited) return;
+    if ((obj->adc == ADC_4) && adc4_inited) return;
+
+    if (obj->adc == ADC_1) {
+        __ADC12_CLK_ENABLE();
+        adc1_inited = 1;
     }
+
+    if (obj->adc == ADC_2) {
+        __ADC12_CLK_ENABLE();
+        adc2_inited = 1;
+    }
+
+    if (obj->adc == ADC_3) {
+        __ADC34_CLK_ENABLE();
+        adc3_inited = 1;
+    }
+
+    if (obj->adc == ADC_4) {
+        __ADC34_CLK_ENABLE();
+        adc4_inited = 1;
+    }
+
+    // Configure ADC
+    AdcHandle.Instance = (ADC_TypeDef *)(obj->adc);
+    AdcHandle.Init.ClockPrescaler        = ADC_CLOCKPRESCALER_PCLK_DIV2;
+    AdcHandle.Init.Resolution            = ADC_RESOLUTION12b;
+    AdcHandle.Init.DataAlign             = ADC_DATAALIGN_RIGHT;
+    AdcHandle.Init.ScanConvMode          = DISABLE;
+    AdcHandle.Init.EOCSelection          = DISABLE;
+    AdcHandle.Init.LowPowerAutoWait      = DISABLE;
+    AdcHandle.Init.ContinuousConvMode    = DISABLE;
+    AdcHandle.Init.NbrOfConversion       = 1;
+    AdcHandle.Init.DiscontinuousConvMode = DISABLE;
+    AdcHandle.Init.NbrOfDiscConversion   = 0;
+    AdcHandle.Init.ExternalTrigConv      = ADC_EXTERNALTRIGCONV_T1_CC1;
+    AdcHandle.Init.ExternalTrigConvEdge  = ADC_EXTERNALTRIGCONVEDGE_NONE;
+    AdcHandle.Init.DMAContinuousRequests = DISABLE;
+    AdcHandle.Init.Overrun               = OVR_DATA_OVERWRITTEN;
+    HAL_ADC_Init(&AdcHandle);
 }
 
 static inline uint16_t adc_read(analogin_t *obj)