Diff: mbed-dev/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/analogin_api.c

Revision:

18:6a4db94011d3

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed-dev/targets/TARGET_NORDIC/TARGET_NRF5/TARGET_MCU_NRF52832/analogin_api.c	Sun May 14 23:18:57 2017 +0000
@@ -0,0 +1,91 @@
+/* mbed Microcontroller Library
+ * Copyright (c) 2006-2013 ARM Limited
+ *
+ * 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 "mbed_assert.h"
+#include "analogin_api.h"
+#include "cmsis.h"
+#include "pinmap.h"
+#include "app_util_platform.h"
+#include "nrf_drv_saadc.h"
+
+#ifdef DEVICE_ANALOGIN
+
+#define ADC_12BIT_RANGE 0xFFF
+#define ADC_RANGE       ADC_12BIT_RANGE
+
+static void analog_in_event_handler(nrf_drv_saadc_evt_t const *p_event)// type of nrf_drv_saadc_event_handler_t 
+{
+    (void) p_event;
+}
+
+static const nrf_drv_saadc_config_t saadc_config = 
+{
+    .resolution         = NRF_SAADC_RESOLUTION_12BIT,
+    .oversample         = NRF_SAADC_OVERSAMPLE_DISABLED,
+    .interrupt_priority = SAADC_CONFIG_IRQ_PRIORITY
+};
+
+void SAADC_IRQHandler(void);
+
+void analogin_init(analogin_t *obj, PinName pin)
+{
+    ret_code_t ret_code;
+    
+    NVIC_SetVector(SAADC_IRQn, (uint32_t)SAADC_IRQHandler);
+    
+    ret_code = nrf_drv_saadc_init(&saadc_config, analog_in_event_handler);
+    MBED_ASSERT(((ret_code == NRF_SUCCESS) || (ret_code == NRF_ERROR_INVALID_STATE))); //NRF_ERROR_INVALID_STATE expected for multiple channels used.
+    
+    uint8_t saadcIn = nrf_drv_saadc_gpio_to_ain(pin);
+    MBED_ASSERT(saadcIn != NRF_SAADC_INPUT_DISABLED);
+    
+    obj->adc     = ADC0_0; // only one instance of ADC in nRF52 SoC
+    obj->adc_pin = saadcIn  - 1;
+    
+    nrf_saadc_channel_config_t channel_config =
+            NRF_DRV_SAADC_DEFAULT_CHANNEL_CONFIG_SE(saadcIn); //Single ended, negative input to ADC shorted to GND.
+    
+    ret_code = nrf_drv_saadc_channel_init(obj->adc_pin, &channel_config);
+    MBED_ASSERT(ret_code == NRF_SUCCESS);
+}
+
+
+uint16_t analogin_read_u16(analogin_t *obj)
+{
+    int16_t    adc_value;
+    ret_code_t ret_code;
+    
+    ret_code = nrf_drv_saadc_sample_convert(obj->adc_pin, &adc_value);
+    MBED_ASSERT(ret_code == NRF_SUCCESS);
+    
+    if (adc_value < 0)
+    {
+        // Even in the single ended mode measured value can be {-0}. Saturation for avoid casting to a big integer.
+        return 0;
+    }
+    else
+    {
+        return (uint16_t) adc_value;
+    }
+}
+
+float analogin_read(analogin_t *obj)
+{
+    uint16_t value = analogin_read_u16(obj);
+    return (float)value * (1.0f / (float)ADC_RANGE);
+}
+
+#endif // DEVICE_ANALOGIN