sigmadelta.h

// Copyright 2015-2016 Espressif Systems (Shanghai) PTE LTD
//
// 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.

#ifndef __DRIVER_SIGMADELTA_H__
#define __DRIVER_SIGMADELTA_H__
#include <esp_types.h>
#include "soc/gpio_sd_struct.h"
#include "soc/gpio_sd_reg.h"
#include "driver/gpio.h"

#ifdef _cplusplus
extern "C" {
#endif

/**
 * @brief Sigma-delta channel list
 */
typedef enum{
    SIGMADELTA_CHANNEL_0 = 0,         /*!< Sigma-delta channel0 */
    SIGMADELTA_CHANNEL_1 = 1,         /*!< Sigma-delta channel1 */
    SIGMADELTA_CHANNEL_2 = 2,         /*!< Sigma-delta channel2 */
    SIGMADELTA_CHANNEL_3 = 3,         /*!< Sigma-delta channel3 */
    SIGMADELTA_CHANNEL_4 = 4,         /*!< Sigma-delta channel4 */
    SIGMADELTA_CHANNEL_5 = 5,         /*!< Sigma-delta channel5 */
    SIGMADELTA_CHANNEL_6 = 6,         /*!< Sigma-delta channel6 */
    SIGMADELTA_CHANNEL_7 = 7,         /*!< Sigma-delta channel7 */
    SIGMADELTA_CHANNEL_MAX,
} sigmadelta_channel_t;

/**
 * @brief Sigma-delta configure struct
 */
typedef struct {
    sigmadelta_channel_t channel;    /*!< Sigma-delta channel number */
    int8_t sigmadelta_duty;          /*!< Sigma-delta duty, duty ranges from -128 to 127. */
    uint8_t sigmadelta_prescale;     /*!< Sigma-delta prescale, prescale ranges from 0 to 255. */
    uint8_t  sigmadelta_gpio;        /*!< Sigma-delta output io number, refer to gpio.h for more details. */
} sigmadelta_config_t;

/**
 * @brief Configure Sigma-delta channel
 *
 * @param  config Pointer of Sigma-delta channel configuration struct
 *
 * @return
 *     - ESP_OK Success
 *     - ESP_ERR_INVALID_ARG Parameter error
 */
esp_err_t sigmadelta_config(const sigmadelta_config_t *config);

/**
 * @brief Set Sigma-delta channel duty.
 *
 *        This function is used to set Sigma-delta channel duty,
 *        If you add a capacitor between the output pin and ground,
 *        the average output voltage Vdc = VDDIO / 256 * duty + VDDIO/2, VDDIO is power supply voltage.
 *
 * @param channel Sigma-delta channel number
 * @param duty Sigma-delta duty of one channel, the value ranges from -128 to 127, recommended range is -90 ~ 90.
 *             The waveform is more like a random one in this range.
 *                                
 * @return
 *     - ESP_OK Success
 *     - ESP_ERR_INVALID_ARG Parameter error
 */
esp_err_t sigmadelta_set_duty(sigmadelta_channel_t channel, int8_t duty);

/**
 * @brief Set Sigma-delta channel's clock pre-scale value.
 *        The source clock is APP_CLK, 80MHz. The clock frequency of the sigma-delta channel is APP_CLK / pre_scale
 *
 * @param channel Sigma-delta channel number
 * @param prescale The divider of source clock, ranges from 0 to 255
 *
 * @return
 *     - ESP_OK Success
 *     - ESP_ERR_INVALID_ARG Parameter error
 */
esp_err_t sigmadelta_set_prescale(sigmadelta_channel_t channel, uint8_t prescale);

/**
 * @brief Set Sigma-delta signal output pin
 *
 * @param channel Sigma-delta channel number
 * @param gpio_num GPIO number of output pin.
 *
 * @return
 *     - ESP_OK Success
 *     - ESP_ERR_INVALID_ARG Parameter error
 */
esp_err_t sigmadelta_set_pin(sigmadelta_channel_t channel, gpio_num_t gpio_num);

#ifdef _cplusplus
}
#endif

#endif