esp-idf/components/driver/adc_common.c

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20 KiB
C

// Copyright 2019 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.
#include <esp_types.h>
#include <stdlib.h>
#include <ctype.h>
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "freertos/timers.h"
#include "esp_log.h"
#include "esp_pm.h"
#include "soc/rtc.h"
#include "driver/rtc_io.h"
#include "driver/dac.h"
#include "sys/lock.h"
#include "driver/gpio.h"
#include "driver/adc.h"
#include "adc1_private.h"
#include "hal/adc_types.h"
#include "hal/adc_hal.h"
#if !CONFIG_IDF_TARGET_ESP32C3
#include "hal/dac_hal.h"
#include "hal/adc_hal_conf.h"
#define ADC_CHECK_RET(fun_ret) ({ \
if (fun_ret != ESP_OK) { \
ESP_LOGE(ADC_TAG,"%s:%d\n",__FUNCTION__,__LINE__); \
return ESP_FAIL; \
} \
})
static const char *ADC_TAG = "ADC";
#define ADC_CHECK(a, str, ret_val) ({ \
if (!(a)) { \
ESP_LOGE(ADC_TAG,"%s(%d): %s", __FUNCTION__, __LINE__, str); \
return (ret_val); \
} \
})
#define ADC_GET_IO_NUM(periph, channel) (adc_channel_io_map[periph][channel])
#define ADC_CHANNEL_CHECK(periph, channel) ADC_CHECK(channel < SOC_ADC_CHANNEL_NUM(periph), "ADC"#periph" channel error", ESP_ERR_INVALID_ARG)
extern portMUX_TYPE rtc_spinlock; //TODO: Will be placed in the appropriate position after the rtc module is finished.
#define ADC_ENTER_CRITICAL() portENTER_CRITICAL(&rtc_spinlock)
#define ADC_EXIT_CRITICAL() portEXIT_CRITICAL(&rtc_spinlock)
/*
In ADC2, there're two locks used for different cases:
1. lock shared with app and Wi-Fi:
ESP32:
When Wi-Fi using the ADC2, we assume it will never stop, so app checks the lock and returns immediately if failed.
ESP32S2:
The controller's control over the ADC is determined by the arbiter. There is no need to control by lock.
2. lock shared between tasks:
when several tasks sharing the ADC2, we want to guarantee
all the requests will be handled.
Since conversions are short (about 31us), app returns the lock very soon,
we use a spinlock to stand there waiting to do conversions one by one.
adc2_spinlock should be acquired first, then adc2_wifi_lock or rtc_spinlock.
*/
// This gets incremented when adc_power_acquire() is called, and decremented when
// adc_power_release() is called. ADC is powered down when the value reaches zero.
// Should be modified within critical section (ADC_ENTER/EXIT_CRITICAL).
static int s_adc_power_on_cnt;
static void adc_power_on_internal(void);
static void adc_power_off_internal(void);
#ifdef CONFIG_IDF_TARGET_ESP32
//prevent ADC2 being used by wifi and other tasks at the same time.
static _lock_t adc2_wifi_lock;
/** For ESP32S2 the ADC2 The right to use ADC2 is controlled by the arbiter, and there is no need to set a lock. */
#define ADC2_WIFI_LOCK_ACQUIRE() _lock_acquire( &adc2_wifi_lock )
#define ADC2_WIFI_LOCK_RELEASE() _lock_release( &adc2_wifi_lock )
#define ADC2_WIFI_LOCK_TRY_ACQUIRE() _lock_try_acquire( &adc2_wifi_lock )
#define ADC2_WIFI_LOCK_CHECK() ((uint32_t *)adc2_wifi_lock != NULL)
#else // !CONFIG_IDF_TARGET_ESP32
#define ADC2_WIFI_LOCK_ACQUIRE()
#define ADC2_WIFI_LOCK_RELEASE()
#define ADC2_WIFI_LOCK_TRY_ACQUIRE() (0) //WIFI controller and rtc controller have independent parameter configuration.
#define ADC2_WIFI_LOCK_CHECK() (true)
#endif // CONFIG_IDF_TARGET_ESP32
//prevent ADC2 being used by tasks (regardless of WIFI)
static portMUX_TYPE adc2_spinlock = portMUX_INITIALIZER_UNLOCKED;
#define ADC2_ENTER_CRITICAL() portENTER_CRITICAL( &adc2_spinlock )
#define ADC2_EXIT_CRITICAL() portEXIT_CRITICAL( &adc2_spinlock )
//prevent ADC1 being used by I2S dma and other tasks at the same time.
static _lock_t adc1_dma_lock;
#define ADC1_DMA_LOCK_ACQUIRE() _lock_acquire( &adc1_dma_lock )
#define ADC1_DMA_LOCK_RELEASE() _lock_release( &adc1_dma_lock )
#if !CONFIG_IDF_TARGET_ESP32
#ifdef CONFIG_PM_ENABLE
static esp_pm_lock_handle_t s_adc2_arbiter_lock;
#endif //CONFIG_PM_ENABLE
#endif // !CONFIG_IDF_TARGET_ESP32
/*---------------------------------------------------------------
ADC Common
---------------------------------------------------------------*/
#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C3
static uint32_t get_calibration_offset(adc_ll_num_t adc_n, adc_channel_t chan)
{
adc_atten_t atten = adc_hal_get_atten(adc_n, chan);
extern uint32_t adc_get_calibration_offset(adc_ll_num_t adc_n, adc_channel_t channel, adc_atten_t atten, bool no_cal);
return adc_get_calibration_offset(adc_n, chan, atten, false);
}
#endif
void adc_power_acquire(void)
{
bool powered_on = false;
ADC_ENTER_CRITICAL();
s_adc_power_on_cnt++;
if (s_adc_power_on_cnt == 1) {
adc_power_on_internal();
powered_on = true;
}
ADC_EXIT_CRITICAL();
if (powered_on) {
ESP_LOGV(ADC_TAG, "%s: ADC powered on", __func__);
}
}
void adc_power_release(void)
{
bool powered_off = false;
ADC_ENTER_CRITICAL();
s_adc_power_on_cnt--;
/* Sanity check */
if (s_adc_power_on_cnt < 0) {
ADC_EXIT_CRITICAL();
ESP_LOGE(ADC_TAG, "%s called, but s_adc_power_on_cnt == 0", __func__);
abort();
} else if (s_adc_power_on_cnt == 0) {
adc_power_off_internal();
powered_off = true;
}
ADC_EXIT_CRITICAL();
if (powered_off) {
ESP_LOGV(ADC_TAG, "%s: ADC powered off", __func__);
}
}
static void adc_power_on_internal(void)
{
ADC_ENTER_CRITICAL();
/* Set the power always on to increase precision. */
adc_hal_set_power_manage(ADC_POWER_SW_ON);
ADC_EXIT_CRITICAL();
}
void adc_power_on(void) __attribute__((alias("adc_power_on_internal")));
static void adc_power_off_internal(void)
{
ADC_ENTER_CRITICAL();
adc_hal_set_power_manage(ADC_POWER_SW_OFF);
ADC_EXIT_CRITICAL();
}
void adc_power_off(void) __attribute__((alias("adc_power_off_internal")));
esp_err_t adc_set_clk_div(uint8_t clk_div)
{
ADC_ENTER_CRITICAL();
adc_hal_digi_set_clk_div(clk_div);
ADC_EXIT_CRITICAL();
return ESP_OK;
}
static void adc_rtc_chan_init(adc_unit_t adc_unit)
{
if (adc_unit & ADC_UNIT_1) {
/* Workaround: Disable the synchronization operation function of ADC1 and DAC.
If enabled(default), ADC RTC controller sampling will cause the DAC channel output voltage. */
dac_hal_rtc_sync_by_adc(false);
adc_hal_rtc_output_invert(ADC_NUM_1, SOC_ADC1_DATA_INVERT_DEFAULT);
adc_hal_set_sar_clk_div(ADC_NUM_1, SOC_ADC_SAR_CLK_DIV_DEFAULT(ADC_NUM_1));
#ifdef CONFIG_IDF_TARGET_ESP32
adc_hal_hall_disable(); //Disable other peripherals.
adc_hal_amp_disable(); //Currently the LNA is not open, close it by default.
#endif
}
if (adc_unit & ADC_UNIT_2) {
adc_hal_pwdet_set_cct(SOC_ADC_PWDET_CCT_DEFAULT);
adc_hal_rtc_output_invert(ADC_NUM_2, SOC_ADC2_DATA_INVERT_DEFAULT);
adc_hal_set_sar_clk_div(ADC_NUM_2, SOC_ADC_SAR_CLK_DIV_DEFAULT(ADC_NUM_2));
}
}
esp_err_t adc_gpio_init(adc_unit_t adc_unit, adc_channel_t channel)
{
gpio_num_t gpio_num = 0;
if (adc_unit & ADC_UNIT_1) {
ADC_CHANNEL_CHECK(ADC_NUM_1, channel);
gpio_num = ADC_GET_IO_NUM(ADC_NUM_1, channel);
}
if (adc_unit & ADC_UNIT_2) {
ADC_CHANNEL_CHECK(ADC_NUM_2, channel);
gpio_num = ADC_GET_IO_NUM(ADC_NUM_2, channel);
}
ADC_CHECK_RET(rtc_gpio_init(gpio_num));
ADC_CHECK_RET(rtc_gpio_set_direction(gpio_num, RTC_GPIO_MODE_DISABLED));
ADC_CHECK_RET(rtc_gpio_pulldown_dis(gpio_num));
ADC_CHECK_RET(rtc_gpio_pullup_dis(gpio_num));
return ESP_OK;
}
esp_err_t adc_set_data_inv(adc_unit_t adc_unit, bool inv_en)
{
ADC_ENTER_CRITICAL();
if (adc_unit & ADC_UNIT_1) {
adc_hal_rtc_output_invert(ADC_NUM_1, inv_en);
}
if (adc_unit & ADC_UNIT_2) {
adc_hal_rtc_output_invert(ADC_NUM_1, inv_en);
}
ADC_EXIT_CRITICAL();
return ESP_OK;
}
esp_err_t adc_set_data_width(adc_unit_t adc_unit, adc_bits_width_t bits)
{
#ifdef CONFIG_IDF_TARGET_ESP32
ADC_CHECK(bits < ADC_WIDTH_MAX, "WIDTH ERR: ESP32 support 9 ~ 12 bit width", ESP_ERR_INVALID_ARG);
#else
ADC_CHECK(bits == ADC_WIDTH_BIT_13, "WIDTH ERR: " CONFIG_IDF_TARGET " support 13 bit width", ESP_ERR_INVALID_ARG);
#endif
ADC_ENTER_CRITICAL();
if (adc_unit & ADC_UNIT_1) {
adc_hal_rtc_set_output_format(ADC_NUM_1, bits);
}
if (adc_unit & ADC_UNIT_2) {
adc_hal_rtc_set_output_format(ADC_NUM_2, bits);
}
ADC_EXIT_CRITICAL();
return ESP_OK;
}
/**
* @brief Reset RTC controller FSM.
*
* @return
* - ESP_OK Success
*/
#if !CONFIG_IDF_TARGET_ESP32
esp_err_t adc_rtc_reset(void)
{
ADC_ENTER_CRITICAL();
adc_hal_rtc_reset();
ADC_EXIT_CRITICAL();
return ESP_OK;
}
#endif
/*-------------------------------------------------------------------------------------
* ADC1
*------------------------------------------------------------------------------------*/
esp_err_t adc1_pad_get_io_num(adc1_channel_t channel, gpio_num_t *gpio_num)
{
ADC_CHANNEL_CHECK(ADC_NUM_1, channel);
int io = ADC_GET_IO_NUM(ADC_NUM_1, channel);
if (io < 0) {
return ESP_ERR_INVALID_ARG;
} else {
*gpio_num = (gpio_num_t)io;
}
return ESP_OK;
}
esp_err_t adc1_config_channel_atten(adc1_channel_t channel, adc_atten_t atten)
{
ADC_CHANNEL_CHECK(ADC_NUM_1, channel);
ADC_CHECK(atten < ADC_ATTEN_MAX, "ADC Atten Err", ESP_ERR_INVALID_ARG);
adc_gpio_init(ADC_UNIT_1, channel);
ADC_ENTER_CRITICAL();
adc_rtc_chan_init(ADC_UNIT_1);
adc_hal_set_atten(ADC_NUM_1, channel, atten);
ADC_EXIT_CRITICAL();
return ESP_OK;
}
esp_err_t adc1_config_width(adc_bits_width_t width_bit)
{
#ifdef CONFIG_IDF_TARGET_ESP32
ADC_CHECK(width_bit < ADC_WIDTH_MAX, "WIDTH ERR: ESP32 support 9 ~ 12 bit width", ESP_ERR_INVALID_ARG);
#elif !defined(CONFIG_IDF_TARGET_ESP32)
ADC_CHECK(width_bit == ADC_WIDTH_BIT_13, "WIDTH ERR: " CONFIG_IDF_TARGET " support 13 bit width", ESP_ERR_INVALID_ARG);
#endif
ADC_ENTER_CRITICAL();
adc_hal_rtc_set_output_format(ADC_NUM_1, width_bit);
ADC_EXIT_CRITICAL();
return ESP_OK;
}
esp_err_t adc1_dma_mode_acquire(void)
{
/* Use locks to avoid digtal and RTC controller conflicts.
for adc1, block until acquire the lock. */
ADC1_DMA_LOCK_ACQUIRE();
ESP_LOGD( ADC_TAG, "dma mode takes adc1 lock." );
ADC_ENTER_CRITICAL();
adc_hal_set_power_manage(ADC_POWER_SW_ON);
/* switch SARADC into DIG channel */
adc_hal_set_controller(ADC_NUM_1, ADC_CTRL_DIG);
ADC_EXIT_CRITICAL();
return ESP_OK;
}
esp_err_t adc1_rtc_mode_acquire(void)
{
/* Use locks to avoid digtal and RTC controller conflicts.
for adc1, block until acquire the lock. */
ADC1_DMA_LOCK_ACQUIRE();
ADC_ENTER_CRITICAL();
/* switch SARADC into RTC channel. */
adc_hal_set_controller(ADC_NUM_1, ADC_CTRL_RTC);
ADC_EXIT_CRITICAL();
return ESP_OK;
}
esp_err_t adc1_lock_release(void)
{
ADC_CHECK((uint32_t *)adc1_dma_lock != NULL, "adc1 lock release called before acquire", ESP_ERR_INVALID_STATE );
/* Use locks to avoid digtal and RTC controller conflicts. for adc1, block until acquire the lock. */
ADC1_DMA_LOCK_RELEASE();
return ESP_OK;
}
int adc1_get_raw(adc1_channel_t channel)
{
int adc_value;
ADC_CHANNEL_CHECK(ADC_NUM_1, channel);
adc1_rtc_mode_acquire();
adc_power_acquire();
#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C3
// Get calibration value before going into critical section
uint32_t cal_val = get_calibration_offset(ADC_NUM_1, channel);
#endif
ADC_ENTER_CRITICAL();
#ifdef CONFIG_IDF_TARGET_ESP32
adc_hal_hall_disable(); //Disable other peripherals.
adc_hal_amp_disable(); //Currently the LNA is not open, close it by default.
#endif
#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C3
adc_hal_set_calibration_param(ADC_NUM_1, cal_val);
#endif
adc_hal_set_controller(ADC_NUM_1, ADC_CTRL_RTC); //Set controller
adc_hal_convert(ADC_NUM_1, channel, &adc_value); //Start conversion, For ADC1, the data always valid.
#if !CONFIG_IDF_TARGET_ESP32
adc_hal_rtc_reset(); //Reset FSM of rtc controller
#endif
ADC_EXIT_CRITICAL();
adc_power_release();
adc1_lock_release();
return adc_value;
}
int adc1_get_voltage(adc1_channel_t channel) //Deprecated. Use adc1_get_raw() instead
{
return adc1_get_raw(channel);
}
#if SOC_ULP_SUPPORTED
void adc1_ulp_enable(void)
{
adc_power_acquire();
ADC_ENTER_CRITICAL();
adc_hal_set_controller(ADC_NUM_1, ADC_CTRL_ULP);
/* since most users do not need LNA and HALL with uLP, we disable them here
open them in the uLP if needed. */
#ifdef CONFIG_IDF_TARGET_ESP32
/* disable other peripherals. */
adc_hal_hall_disable();
adc_hal_amp_disable();
#endif
ADC_EXIT_CRITICAL();
}
#endif
/*---------------------------------------------------------------
ADC2
---------------------------------------------------------------*/
esp_err_t adc2_pad_get_io_num(adc2_channel_t channel, gpio_num_t *gpio_num)
{
ADC_CHANNEL_CHECK(ADC_NUM_2, channel);
int io = ADC_GET_IO_NUM(ADC_NUM_2, channel);
if (io < 0) {
return ESP_ERR_INVALID_ARG;
} else {
*gpio_num = (gpio_num_t)io;
}
return ESP_OK;
}
/** For ESP32S2 the ADC2 The right to use ADC2 is controlled by the arbiter, and there is no need to set a lock.*/
esp_err_t adc2_wifi_acquire(void)
{
/* Wi-Fi module will use adc2. Use locks to avoid conflicts. */
ADC2_WIFI_LOCK_ACQUIRE();
ESP_LOGD( ADC_TAG, "Wi-Fi takes adc2 lock." );
return ESP_OK;
}
esp_err_t adc2_wifi_release(void)
{
ADC_CHECK(ADC2_WIFI_LOCK_CHECK(), "wifi release called before acquire", ESP_ERR_INVALID_STATE );
ADC2_WIFI_LOCK_RELEASE();
ESP_LOGD( ADC_TAG, "Wi-Fi returns adc2 lock." );
return ESP_OK;
}
esp_err_t adc2_config_channel_atten(adc2_channel_t channel, adc_atten_t atten)
{
ADC_CHANNEL_CHECK(ADC_NUM_2, channel);
ADC_CHECK(atten <= ADC_ATTEN_11db, "ADC2 Atten Err", ESP_ERR_INVALID_ARG);
adc_gpio_init(ADC_UNIT_2, channel);
ADC2_ENTER_CRITICAL();
//avoid collision with other tasks
if ( ADC2_WIFI_LOCK_TRY_ACQUIRE() == -1 ) {
//try the lock, return if failed (wifi using).
ADC2_EXIT_CRITICAL();
return ESP_ERR_TIMEOUT;
}
adc_rtc_chan_init(ADC_UNIT_2);
adc_hal_set_atten(ADC_NUM_2, channel, atten);
ADC2_WIFI_LOCK_RELEASE();
ADC2_EXIT_CRITICAL();
return ESP_OK;
}
static inline void adc2_config_width(adc_bits_width_t width_bit)
{
#if !CONFIG_IDF_TARGET_ESP32
#ifdef CONFIG_PM_ENABLE
/* Lock APB clock. */
if (s_adc2_arbiter_lock == NULL) {
esp_pm_lock_create(ESP_PM_APB_FREQ_MAX, 0, "adc2", &s_adc2_arbiter_lock);
}
#endif //CONFIG_PM_ENABLE
#endif //CONFIG_IDF_TARGET_ESP32S2
ADC_ENTER_CRITICAL();
adc_hal_rtc_set_output_format(ADC_NUM_2, width_bit);
ADC_EXIT_CRITICAL();
}
static inline void adc2_dac_disable( adc2_channel_t channel)
{
#ifdef CONFIG_IDF_TARGET_ESP32
if ( channel == ADC2_CHANNEL_8 ) { // the same as DAC channel 1
dac_output_disable(DAC_CHANNEL_1);
} else if ( channel == ADC2_CHANNEL_9 ) {
dac_output_disable(DAC_CHANNEL_2);
}
#else
if ( channel == ADC2_CHANNEL_6 ) { // the same as DAC channel 1
dac_output_disable(DAC_CHANNEL_1);
} else if ( channel == ADC2_CHANNEL_7 ) {
dac_output_disable(DAC_CHANNEL_2);
}
#endif
}
/**
* @note For ESP32S2:
* The arbiter's working clock is APB_CLK. When the APB_CLK clock drops below 8 MHz, the arbiter must be in shield mode.
* Or, the RTC controller will fail when get raw data.
* This issue does not occur on digital controllers (DMA mode), and the hardware guarantees that there will be no errors.
*/
esp_err_t adc2_get_raw(adc2_channel_t channel, adc_bits_width_t width_bit, int *raw_out)
{
int adc_value = 0;
ADC_CHECK(raw_out != NULL, "ADC out value err", ESP_ERR_INVALID_ARG);
ADC_CHECK(channel < ADC2_CHANNEL_MAX, "ADC Channel Err", ESP_ERR_INVALID_ARG);
#ifdef CONFIG_IDF_TARGET_ESP32
ADC_CHECK(width_bit < ADC_WIDTH_MAX, "WIDTH ERR: ESP32 support 9 ~ 12 bit width", ESP_ERR_INVALID_ARG);
#else
ADC_CHECK(width_bit == ADC_WIDTH_BIT_13, "WIDTH ERR: ESP32S2 support 13 bit width", ESP_ERR_INVALID_ARG);
#endif
adc_power_acquire(); //in critical section with whole rtc module
#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C3
// Get calibration value before going into critical section
uint32_t cal_val = get_calibration_offset(ADC_NUM_2, channel);
#endif
ADC2_ENTER_CRITICAL(); //avoid collision with other tasks
if ( ADC2_WIFI_LOCK_TRY_ACQUIRE() == -1 ) { //try the lock, return if failed (wifi using).
ADC2_EXIT_CRITICAL();
adc_power_release();
return ESP_ERR_TIMEOUT;
}
#ifdef CONFIG_ADC_DISABLE_DAC
adc2_dac_disable(channel); //disable other peripherals
#endif
adc2_config_width(width_bit); // in critical section with whole rtc module. because the PWDET use the same registers, place it here.
#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3 || CONFIG_IDF_TARGET_ESP32C3
adc_hal_set_calibration_param(ADC_NUM_2, cal_val);
#endif
adc_hal_set_controller(ADC_NUM_2, ADC_CTRL_RTC);// set controller
#if !CONFIG_IDF_TARGET_ESP32
#ifdef CONFIG_PM_ENABLE
if (s_adc2_arbiter_lock) {
esp_pm_lock_acquire(s_adc2_arbiter_lock);
}
#endif //CONFIG_PM_ENABLE
#endif //CONFIG_IDF_TARGET_ESP32
if (adc_hal_convert(ADC_NUM_2, channel, &adc_value)) {
adc_value = -1;
}
#if CONFIG_IDF_TARGET_ESP32S2 || CONFIG_IDF_TARGET_ESP32S3
#ifdef CONFIG_PM_ENABLE
/* Release APB clock. */
if (s_adc2_arbiter_lock) {
esp_pm_lock_release(s_adc2_arbiter_lock);
}
#endif //CONFIG_PM_ENABLE
#endif //CONFIG_IDF_TARGET_ESP32
#if !CONFIG_IDF_TARGET_ESP32
adc_rtc_reset();
#endif
ADC2_WIFI_LOCK_RELEASE();
ADC2_EXIT_CRITICAL();
if (adc_value < 0) {
ESP_LOGD( ADC_TAG, "ADC2 ARB: Return data is invalid." );
adc_power_release();
return ESP_ERR_INVALID_STATE;
}
//in critical section with whole rtc module
adc_power_release();
*raw_out = adc_value;
return ESP_OK;
}
esp_err_t adc2_vref_to_gpio(gpio_num_t gpio)
{
return adc_vref_to_gpio(ADC_UNIT_2, gpio);
}
esp_err_t adc_vref_to_gpio(adc_unit_t adc_unit, gpio_num_t gpio)
{
#ifdef CONFIG_IDF_TARGET_ESP32
adc_power_acquire();
if (adc_unit & ADC_UNIT_1) {
adc_power_release();
return ESP_ERR_INVALID_ARG;
}
#endif
adc2_channel_t ch = ADC2_CHANNEL_MAX;
/* Check if the GPIO supported. */
for (int i = 0; i < ADC2_CHANNEL_MAX; i++) {
if (gpio == ADC_GET_IO_NUM(ADC_NUM_2, i)) {
ch = i;
break;
}
}
if (ch == ADC2_CHANNEL_MAX) {
adc_power_release();
return ESP_ERR_INVALID_ARG;
}
ADC_ENTER_CRITICAL();
adc_hal_set_power_manage(ADC_POWER_SW_ON);
if (adc_unit & ADC_UNIT_1) {
adc_hal_vref_output(ADC_NUM_1, ch, true);
} else if (adc_unit & ADC_UNIT_2) {
adc_hal_vref_output(ADC_NUM_2, ch, true);
}
ADC_EXIT_CRITICAL();
//Configure RTC gpio, Only ADC2's channels IO are supported to output reference voltage.
adc_gpio_init(ADC_UNIT_2, ch);
return ESP_OK;
}
#endif // !CONFIG_IDF_TARGET_ESP32C3