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+/******************************************************************//**
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+ * @file drv_adc.c
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+ * @brief ADC driver of RT-Thread RTOS for EFM32
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+ * COPYRIGHT (C) 2011, RT-Thread Development Team
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+ * @author onelife
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+ * @version 0.4 beta
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+ **********************************************************************
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+ * @section License
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+ * The license and distribution terms for this file may be found in the file LICENSE in this
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+ * distribution or at http://www.rt-thread.org/license/LICENSE
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+ **********************************************************************
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+ * @section Change Logs
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+ * Date Author Notes
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+ * 2011-02-21 onelife Initial creation for EFM32
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+ *********************************************************************/
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+
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+/******************************************************************//**
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+* @addtogroup efm32
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+* @{
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+*********************************************************************/
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+
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+/* Includes -------------------------------------------------------------------*/
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+#include "board.h"
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+#include "drv_adc.h"
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+
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+/* Private typedef -------------------------------------------------------------*/
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+/* Private define --------------------------------------------------------------*/
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+/* Private macro --------------------------------------------------------------*/
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+/* Private variables ------------------------------------------------------------*/
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+#ifdef RT_USING_ADC0
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+ static struct rt_device adc0_device;
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+#endif
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+
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+/* Private function prototypes ---------------------------------------------------*/
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+rt_uint32_t efm32_adc_calibration(
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+ ADC_TypeDef *adc,
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+ ADC_Ref_TypeDef ref,
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+ ADC_SingleInput_TypeDef input);
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+
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+/* Private functions ------------------------------------------------------------*/
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+/******************************************************************//**
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+ * @brief
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+ * Initialize ADC device
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+ *
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+ * @details
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+ *
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+ * @note
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+ *
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+ * @param[in] dev
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+ * Pointer to device descriptor
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+ *
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+ * @return
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+ * Error code
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+ *********************************************************************/
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+ static rt_err_t rt_adc_init(rt_device_t dev)
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+{
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+ RT_ASSERT(dev != RT_NULL);
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+
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+ rt_uint32_t temp;
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+
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+ struct efm32_adc_device_t *adc;
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+
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+ adc = (struct efm32_adc_device_t *)(dev->user_data);
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+
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+ temp = efm32_adc_calibration(adc->adc_device, ADC_INIT_REF, ADC_INIT_CH);
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+
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+#ifdef RT_ADC_DEBUG
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+ rt_kprintf("adc->CAL = %x\n", temp);
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+#endif
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+
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+ return RT_EOK;
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+}
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+
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+/******************************************************************//**
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+* @brief
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+* Configure ADC device
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+*
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+* @details
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+*
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+* @note
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+*
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+* @param[in] dev
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+* Pointer to device descriptor
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+*
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+* @param[in] cmd
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+* ADC control command
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+*
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+* @param[in] args
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+* Arguments
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+*
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+* @return
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+* Error code
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+*********************************************************************/
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+static rt_err_t rt_adc_control(
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+ rt_device_t dev,
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+ rt_uint8_t cmd,
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+ void *args)
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+{
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+ RT_ASSERT(dev != RT_NULL);
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+
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+ struct efm32_adc_device_t *adc;
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+
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+ adc = (struct efm32_adc_device_t *)(dev->user_data);
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+
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+ switch (cmd)
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+ {
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+ case RT_DEVICE_CTRL_SUSPEND:
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+ /* Suspend device */
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+ dev->flag |= RT_DEVICE_FLAG_SUSPENDED;
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+ adc->adc_device->CMD = ADC_CMD_SINGLESTOP | ADC_CMD_SCANSTOP;
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+ break;
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+
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+ case RT_DEVICE_CTRL_RESUME:
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+ /* Resume device */
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+ dev->flag &= ~RT_DEVICE_FLAG_SUSPENDED;
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+
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+ switch (adc->mode)
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+ {
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+ case ADC_MODE_SINGLE:
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+ ADC_Start(adc->adc_device, adcStartSingle);
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+ break;
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+
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+ case ADC_MODE_SCAN:
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+ ADC_Start(adc->adc_device, adcStartScan);
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+ break;
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+
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+ case ADC_MODE_TAILGATE:
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+ ADC_Start(adc->adc_device, adcStartScanAndSingle);
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+ break;
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+
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+ default:
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+ return -RT_ERROR;
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+ }
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+ break;
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+
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+ case RT_DEVICE_CTRL_ADC_MODE:
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+ {
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+ /* change device setting */
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+ struct efm32_adc_control_t *control;
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+
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+ control = (struct efm32_adc_control_t *)args;
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+
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+ switch (control->mode)
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+ {
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+ case ADC_MODE_SINGLE:
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+ ADC_InitSingle(adc->adc_device, control->singleInit);
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+ break;
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+
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+ case ADC_MODE_SCAN:
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+ ADC_InitScan(adc->adc_device, control->scanInit);
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+ break;
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+
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+ case ADC_MODE_TAILGATE:
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+ ADC_InitSingle(adc->adc_device, control->singleInit);
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+ ADC_InitScan(adc->adc_device, control->scanInit);
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+ break;
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+
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+ default:
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+ return -RT_ERROR;
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+ }
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+
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+ adc->mode = control->mode;
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+ }
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+ break;
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+
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+ case RT_DEVICE_CTRL_ADC_RESULT:
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+ switch (adc->mode)
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+ {
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+ case ADC_MODE_SINGLE:
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+ while (adc->adc_device->STATUS & ADC_STATUS_SINGLEACT);
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+ *((rt_uint32_t *)args) = ADC_DataSingleGet(adc->adc_device);
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+ break;
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+
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+ case ADC_MODE_SCAN:
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+ while (adc->adc_device->STATUS & ADC_STATUS_SCANACT);
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+ *((rt_uint32_t *)args) = ADC_DataScanGet(adc->adc_device);
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+ break;
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+
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+ case ADC_MODE_TAILGATE:
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+ while (adc->adc_device->STATUS & ADC_STATUS_SCANACT);
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+ *((rt_uint32_t *)args) = ADC_DataScanGet(adc->adc_device);
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+
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+ while (adc->adc_device->STATUS & ADC_STATUS_SINGLEACT);
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+ *((rt_uint32_t *)args + 1) = ADC_DataSingleGet(adc->adc_device);
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+ break;
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+
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+ default:
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+ return -RT_ERROR;
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+ }
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+ break;
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+ }
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+
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+ return RT_EOK;
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+}
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+
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+/******************************************************************//**
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+* @brief
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+* Register ADC device
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+*
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+* @details
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+*
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+* @note
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+*
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+* @param[in] device
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+* Pointer to device descriptor
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+*
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+* @param[in] name
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+* Device name
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+*
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+* @param[in] flag
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+* Configuration flags
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+*
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+* @param[in] adc
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+* Pointer to ADC device descriptor
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+*
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+* @return
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+* Error code
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+*********************************************************************/
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+rt_err_t rt_hw_adc_register(
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+ rt_device_t device,
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+ const char *name,
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+ rt_uint32_t flag,
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+ struct efm32_adc_device_t *adc)
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+{
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+ RT_ASSERT(device != RT_NULL);
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+
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+ device->type = RT_Device_Class_Char; /* fixme: should be adc type */
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+ device->rx_indicate = RT_NULL;
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+ device->tx_complete = RT_NULL;
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+ device->init = rt_adc_init;
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+ device->open = RT_NULL;
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+ device->close = RT_NULL;
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+ device->read = RT_NULL;
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+ device->write = RT_NULL;
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+ device->control = rt_adc_control;
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+ device->user_data = adc;
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+
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+ /* register a character device */
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+ return rt_device_register(device, name, flag);
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+}
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+
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+/******************************************************************//**
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+* @brief
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+* Initialize all ADC module related hardware and register ADC device to kernel
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+*
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+* @details
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+*
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+* @note
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+*
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+*********************************************************************/
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+void rt_hw_adc_init(void)
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+{
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+ struct efm32_adc_device_t *adc;
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+ ADC_Init_TypeDef init = ADC_INIT_DEFAULT;
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+
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+ init.ovsRateSel = adcOvsRateSel4096; //TODO
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+ init.timebase = ADC_TimebaseCalc(0);
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+ init.prescale = ADC_PrescaleCalc(ADC_CONVERT_FREQUENCY, 0);
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+
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+
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+#ifdef RT_USING_ADC0
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+ adc = rt_malloc(sizeof(struct efm32_adc_device_t));
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+ if (adc == RT_NULL)
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+ {
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+ rt_kprintf("no memory for ADC driver\n");
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+ return;
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+ }
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+ adc->adc_device = ADC0;
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+ adc->mode = ADC_MODE_SINGLE;
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+
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+ /* Enable clock for ADCn module */
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+ CMU_ClockEnable(cmuClock_ADC0, true);
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+
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+ /* Reset */
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+ ADC_Reset(ADC0);
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+
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+ /* Configure ADC */
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+ ADC_Init(adc->adc_device, &init);
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+
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+ rt_hw_adc_register(&adc0_device, RT_ADC0_NAME, EFM32_NO_DATA, adc);
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+#endif
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+}
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+
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+
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+/***************************************************************************//**
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+ * @brief
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+ * Calibrate offset and gain for the specified reference.
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+ * Supports currently only single ended gain calibration.
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+ * Could easily be expanded to support differential gain calibration.
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+ *
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+ * @details
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+ * The offset calibration routine measures 0 V with the ADC, and adjust
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+ * the calibration register until the converted value equals 0.
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+ * The gain calibration routine needs an external reference voltage equal
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+ * to the top value for the selected reference. For example if the 2.5 V
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+ * reference is to be calibrated, the external supply must also equal 2.5V.
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+ *
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+ * @param[in] adc
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+ * Pointer to ADC peripheral register block.
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+ *
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+ * @param[in] ref
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+ * Reference used during calibration. Can be both external and internal
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+ * references.
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+ *
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+ * @param[in] input
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+ * Input channel used during calibration.
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+ *
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+ * @return
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+ * The final value of the calibration register, note that the calibration
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+ * register gets updated with this value during the calibration.
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+ * No need to load the calibration values after the function returns.
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+ ******************************************************************************/
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+rt_uint32_t efm32_adc_calibration(
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+ ADC_TypeDef *adc,
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+ ADC_Ref_TypeDef ref,
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+ ADC_SingleInput_TypeDef input)
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+{
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+ rt_uint32_t cal;
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+ rt_int32_t sample;
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+ rt_int8_t high, mid, low, tmp;
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+ ADC_InitSingle_TypeDef singleInit = ADC_INITSINGLE_DEFAULT;
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+
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+ /* Init for single conversion use, measure diff 0 with selected reference. */
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+ singleInit.reference = ref;
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+ singleInit.input = adcSingleInpDiff0;
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+ singleInit.acqTime = adcAcqTime32;
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+ singleInit.diff = true;
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+ /* Enable oversampling rate */
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+ singleInit.resolution = adcResOVS;
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+ ADC_InitSingle(adc, &singleInit);
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+
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+ /* ADC is now set up for offset calibration */
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+ /* Offset calibration register is a 7 bit signed 2's complement value. */
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+ /* Use unsigned indexes for binary search, and convert when calibration */
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+ /* register is written to. */
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+ high = 63;
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+ low = -64;
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+
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+ /* Do binary search for offset calibration*/
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+ while (low < high)
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+ {
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+ /* Calculate midpoint */
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+ mid = low + (high - low) / 2;
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+
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+ /* Midpoint is converted to 2's complement and written to both scan and */
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+ /* single calibration registers */
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+ cal = adc->CAL & ~(_ADC_CAL_SINGLEOFFSET_MASK | _ADC_CAL_SCANOFFSET_MASK);
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+ tmp = mid < 0 ? (mid & 0x3F ^ 0x3F | 0x40) + 1 : mid;
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+ cal |= tmp << _ADC_CAL_SINGLEOFFSET_SHIFT;
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+ cal |= tmp << _ADC_CAL_SCANOFFSET_SHIFT;
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+#ifdef RT_ADC_DEBUG
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+ rt_kprintf("adc->CAL = %x, cal = %x, tmp = %x\n", adc->CAL, cal, tmp);
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+#endif
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+ adc->CAL = cal;
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+
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+ /* Do a conversion */
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+ ADC_Start(adc, adcStartSingle);
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+
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+ /* Wait while conversion is active */
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+ while (adc->STATUS & ADC_STATUS_SINGLEACT) ;
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+
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+ /* Get ADC result */
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+ sample = ADC_DataSingleGet(adc);
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+
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+ /* Check result and decide in which part of to repeat search */
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+ /* Calibration register has negative effect on result */
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+ if (sample < 0)
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+ {
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+ /* Repeat search in bottom half. */
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+ high = mid;
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+ }
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+ else if (sample > 0)
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+ {
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+ /* Repeat search in top half. */
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+ low = mid + 1;
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+ }
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+ else
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+ {
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+ /* Found it, exit while loop */
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+ break;
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+ }
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+ }
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+#ifdef RT_ADC_DEBUG
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+ rt_kprintf("adc->CAL = %x\n", adc->CAL);
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+#endif
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+
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+ /* Now do gain calibration, only input and diff settings needs to be changed */
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+ adc->SINGLECTRL &= ~(_ADC_SINGLECTRL_INPUTSEL_MASK | _ADC_SINGLECTRL_DIFF_MASK);
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+ adc->SINGLECTRL |= (input << _ADC_SINGLECTRL_INPUTSEL_SHIFT);
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+ adc->SINGLECTRL |= (false << _ADC_SINGLECTRL_DIFF_SHIFT);
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+
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+ /* ADC is now set up for gain calibration */
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+ /* Gain calibration register is a 7 bit unsigned value. */
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+ high = 127;
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+ low = 0;
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+
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+ /* Do binary search for gain calibration */
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+ while (low < high)
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+ {
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+ /* Calculate midpoint and write to calibration register */
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+ mid = low + (high - low) / 2;
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+
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+ /* Midpoint is converted to 2's complement */
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+ cal = adc->CAL & ~(_ADC_CAL_SINGLEGAIN_MASK | _ADC_CAL_SCANGAIN_MASK);
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+ cal |= mid << _ADC_CAL_SINGLEGAIN_SHIFT;
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+ cal |= mid << _ADC_CAL_SCANGAIN_SHIFT;
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+#ifdef RT_ADC_DEBUG
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+ rt_kprintf("adc->CAL = %x, cal = %x, mid = %x\n", adc->CAL, cal, mid);
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+#endif
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+ adc->CAL = cal;
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+
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+ /* Do a conversion */
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+ ADC_Start(adc, adcStartSingle);
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+
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+ /* Wait while conversion is active */
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+ while (adc->STATUS & ADC_STATUS_SINGLEACT) ;
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+
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+ /* Get ADC result */
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+ sample = ADC_DataSingleGet(adc);
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+
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+ /* Check result and decide in which part to repeat search */
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+ /* Compare with a value atleast one LSB's less than top to avoid overshooting */
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+ /* Since oversampling is used, the result is 16 bits, but a couple of lsb's */
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+ /* applies to the 12 bit result value, if 0xffe is the top value in 12 bit, this */
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+ /* is in turn 0xffe0 in the 16 bit result. */
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+ /* Calibration register has positive effect on result */
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+ if (sample > 0xffd0)
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|
+ {
|
|
|
+ /* Repeat search in bottom half. */
|
|
|
+ high = mid;
|
|
|
+ }
|
|
|
+ else if (sample < 0xffd0)
|
|
|
+ {
|
|
|
+ /* Repeat search in top half. */
|
|
|
+ low = mid + 1;
|
|
|
+ }
|
|
|
+ else
|
|
|
+ {
|
|
|
+ /* Found it, exit while loop */
|
|
|
+ break;
|
|
|
+ }
|
|
|
+ }
|
|
|
+#ifdef RT_ADC_DEBUG
|
|
|
+ rt_kprintf("adc->CAL = %x\n", adc->CAL);
|
|
|
+#endif
|
|
|
+
|
|
|
+ return adc->CAL;
|
|
|
+}
|
|
|
+
|
|
|
+/******************************************************************//**
|
|
|
+ * @}
|
|
|
+*********************************************************************/
|