File content as of revision 627:4fa1328d9c60:

/***************************************************************************//**
 * @file analogin_api.c
 *******************************************************************************
 * @section License
 * <b>(C) Copyright 2015 Silicon Labs, http://www.silabs.com</b>
 *******************************************************************************
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 *    claim that you wrote the original software.
 * 2. Altered source versions must be plainly marked as such, and must not be
 *    misrepresented as being the original software.
 * 3. This notice may not be removed or altered from any source distribution.
 *
 * DISCLAIMER OF WARRANTY/LIMITATION OF REMEDIES: Silicon Labs has no
 * obligation to support this Software. Silicon Labs is providing the
 * Software "AS IS", with no express or implied warranties of any kind,
 * including, but not limited to, any implied warranties of merchantability
 * or fitness for any particular purpose or warranties against infringement
 * of any proprietary rights of a third party.
 *
 * Silicon Labs will not be liable for any consequential, incidental, or
 * special damages, or any other relief, or for any claim by any third party,
 * arising from your use of this Software.
 *
 ******************************************************************************/

#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"

uint8_t analogin_get_index(analogin_t *obj)
{
    return 0; //only one module availalbe
}

void analogin_preinit(analogin_t *obj, PinName pin)
{
    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);
}

void analogin_init(analogin_t *obj, PinName pin)
{
    static uint8_t adc_initialized = 0;

    /* Init structure */
    analogin_preinit(obj, pin);

    /* 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;
    }
}

void analogin_enable(analogin_t *obj, uint8_t enable)
{
    //not avail for EFM32
}

void analogin_enable_pins(analogin_t *obj, uint8_t enable)
{
    //not avail for EFM32
}

void analogin_enable_interrupt(analogin_t *obj, uint32_t address, uint8_t enable)
{
    NVIC_SetVector(ADC0_IRQn, address);
    if (enable) {
        // enable end of conversion interrupt
        ADC_IntEnable(obj->adc, ADC_IEN_SCAN);
        ADC_IntSet(obj->adc, ADC_IF_SCAN);
        NVIC_EnableIRQ(ADC0_IRQn);
    } else {
        ADC_IntDisable(obj->adc, ADC_IEN_SCAN);
        ADC_IntClear(obj->adc, ADC_IF_SCAN);
        NVIC_DisableIRQ(ADC0_IRQn);
    }
}

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
    adc->SINGLECTRL = (adc->SINGLECTRL & ~_ADC_SINGLECTRL_INPUTSEL_MASK) | obj->channel;

    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