File content as of revision 174:ed647f63e28d:

/* mbed Microcontroller Library
 * Copyright (c) 2015, STMicroelectronics
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 * 3. Neither the name of STMicroelectronics nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
#include "mbed_assert.h"
#include "analogout_api.h"

#if DEVICE_ANALOGOUT

#include "cmsis.h"
#include "pinmap.h"
#include "mbed_error.h"
#include "PeripheralPins.h"

// These variables are used for the "free" function
static int channel1_used = 0;
static int channel2_used = 0;

void analogout_init(dac_t *obj, PinName pin) {
    DAC_ChannelConfTypeDef sConfig;

    // Get the peripheral name from the pin and assign it to the object
    obj->dac = (DACName)pinmap_peripheral(pin, PinMap_DAC);
    MBED_ASSERT(obj->dac != (DACName)NC);

    // Get the pin function and assign the used channel to the object
    uint32_t function = pinmap_function(pin, PinMap_DAC);
    MBED_ASSERT(function != (uint32_t)NC);
    switch (STM_PIN_CHANNEL(function)) {
        case 1:
            obj->channel = DAC_CHANNEL_1;
            break;
#if defined(DAC_CHANNEL_2)
        case 2:
            obj->channel = DAC_CHANNEL_2;
            break;
#endif
        default:
            error("Unknown DAC channel");
            break;
    }

    // Configure GPIO
    pinmap_pinout(pin, PinMap_DAC);

    // Save the pin for future use
    obj->pin = pin;

    // Enable DAC clock
    __DAC_CLK_ENABLE();

    // Configure DAC
    obj->handle.Instance = DAC;
    if (HAL_DAC_Init(&obj->handle) != HAL_OK ) {
        error("HAL_DAC_Init failed");
    }

    sConfig.DAC_Trigger      = DAC_TRIGGER_NONE;
    sConfig.DAC_OutputBuffer = DAC_OUTPUTBUFFER_ENABLE;

    if (HAL_DAC_ConfigChannel(&obj->handle, &sConfig, obj->channel) != HAL_OK) {
        error("Cannot configure DAC channel 2");
    }

    if (obj->channel == DAC_CHANNEL_1) {
        channel1_used = 1;
    } else {
        channel2_used = 1;
    }

    analogout_write_u16(obj, 0);
}

void analogout_free(dac_t *obj) {
    // Reset DAC and disable clock
    if (obj->channel == DAC_CHANNEL_1) channel1_used = 0;
#if defined(DAC_CHANNEL_2)
    if (obj->channel == DAC_CHANNEL_2) channel2_used = 0;
#endif
    if ((channel1_used == 0) && (channel2_used == 0)) {
        __DAC_FORCE_RESET();
        __DAC_RELEASE_RESET();
        __DAC_CLK_DISABLE();
    }

    // Configure GPIO
    pin_function(obj->pin, STM_PIN_DATA(STM_MODE_INPUT, GPIO_NOPULL, 0));
}

#endif // DEVICE_ANALOGOUT