456 lines
12 KiB
C
456 lines
12 KiB
C
/******************************************************************//**
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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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* @addtogroup efm32
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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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/* 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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/* 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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/* 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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rt_uint32_t temp;
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struct efm32_adc_device_t *adc;
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adc = (struct efm32_adc_device_t *)(dev->user_data);
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temp = efm32_adc_calibration(adc->adc_device, ADC_INIT_REF, ADC_INIT_CH);
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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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return RT_EOK;
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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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struct efm32_adc_device_t *adc;
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adc = (struct efm32_adc_device_t *)(dev->user_data);
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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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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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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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case ADC_MODE_SCAN:
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ADC_Start(adc->adc_device, adcStartScan);
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break;
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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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default:
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return -RT_ERROR;
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}
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break;
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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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control = (struct efm32_adc_control_t *)args;
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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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case ADC_MODE_SCAN:
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ADC_InitScan(adc->adc_device, control->scanInit);
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break;
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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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default:
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return -RT_ERROR;
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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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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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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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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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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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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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return RT_EOK;
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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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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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/* 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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* @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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// TODO: Fixed oversampling rate?
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init.ovsRateSel = adcOvsRateSel4096;
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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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#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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#ifdef RT_ADC_DEBUG
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rt_kprintf("no memory for ADC driver\n");
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#endif
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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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/* Enable clock for ADCn module */
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CMU_ClockEnable(cmuClock_ADC0, true);
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/* Reset */
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ADC_Reset(ADC0);
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/* Configure ADC */
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ADC_Init(adc->adc_device, &init);
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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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* @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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/* 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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/* 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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/* 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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/* 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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/* Do a conversion */
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ADC_Start(adc, adcStartSingle);
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/* Wait while conversion is active */
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while (adc->STATUS & ADC_STATUS_SINGLEACT) ;
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/* Get ADC result */
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sample = ADC_DataSingleGet(adc);
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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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/* 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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/* 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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/* 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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/* 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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/* Do a conversion */
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ADC_Start(adc, adcStartSingle);
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/* Wait while conversion is active */
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while (adc->STATUS & ADC_STATUS_SINGLEACT) ;
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/* Get ADC result */
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sample = ADC_DataSingleGet(adc);
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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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{
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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 < 0xffd0)
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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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return adc->CAL;
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}
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/******************************************************************//**
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* @}
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*********************************************************************/
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