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DFR1075 - Firebeetle 2 - ESP32-c6 analog read

iisfaq 2025-03-02 07:45:04 497 Views2 Replies
I have a simple app that performs an Analog read from A1 (ADC1_2) and A2 (ADC1_3)

I have a LDR connected to 10K resister and I am reading this value.

The ADC 1 channel 2 gives me a light value of 192 and a dark value of 1456.

The ADC 1 channel 3 gives me a light value of 176 and a dark value of 336

Why is this?

I have tried disabling pull up and pull down on the channels. Made no difference.

The pins appear to be quite generic and not really connected to anything else.

I am wondering why the difference in values. And is there any way to make them the same value?

I am using ESP-IDF because arduino IDE seems to have issues with serial ports on these devices now. Also I could not upload the code as a file as it says 10MB.

/*
* SPDX-FileCopyrightText: 2022-2023 Espressif Systems (Shanghai) CO LTD
*
* SPDX-License-Identifier: Apache-2.0
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "soc/soc_caps.h"
#include "esp_log.h"
#include "esp_adc/adc_oneshot.h"
#include "esp_adc/adc_cali.h"
#include "esp_adc/adc_cali_scheme.h"
#include "driver/gpio.h"

const static char *TAG = "EXAMPLE";

/*---------------------------------------------------------------
ADC General Macros
---------------------------------------------------------------*/
//ADC1 Channels
#define EXAMPLE_ADC1_CHAN0 ADC_CHANNEL_2
#define EXAMPLE_ADC1_CHAN1 ADC_CHANNEL_3

// GPIO pins corresponding to ADC channels
#define GPIO_ADC1_CHAN0 2 // GPIO 2 for ADC Channel 2
#define GPIO_ADC1_CHAN1 3 // GPIO 3 for ADC Channel 3

#define EXAMPLE_ADC_ATTEN ADC_ATTEN_DB_12

static int adc_raw[2]; // Store one reading per channel
static bool do_calibration = true;
static adc_cali_handle_t adc1_cali_handle = NULL;

static bool init_adc_calibration(void) {
esp_err_t ret = ESP_FAIL;
bool calibration_enabled = false;

#if ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED
if (!calibration_enabled) {
ESP_LOGI(TAG, "Calibration scheme: Curve Fitting");
adc_cali_curve_fitting_config_t cali_config = {
.unit_id = ADC_UNIT_1,
.atten = EXAMPLE_ADC_ATTEN,
.bitwidth = ADC_BITWIDTH_12,
};
ret = adc_cali_create_scheme_curve_fitting(&cali_config, &adc1_cali_handle);
if (ret == ESP_OK) {
calibration_enabled = true;
}
}
#endif

#if ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED
if (!calibration_enabled) {
ESP_LOGI(TAG, "Calibration scheme: Line Fitting");
adc_cali_line_fitting_config_t cali_config = {
.unit_id = ADC_UNIT_1,
.atten = EXAMPLE_ADC_ATTEN,
.bitwidth = ADC_BITWIDTH_12,
};
ret = adc_cali_create_scheme_line_fitting(&cali_config, &adc1_cali_handle);
if (ret == ESP_OK) {
calibration_enabled = true;
}
}
#endif

return calibration_enabled;
}

static void deinit_adc_calibration(void) {
if (adc1_cali_handle) {
#if ADC_CALI_SCHEME_CURVE_FITTING_SUPPORTED
adc_cali_delete_scheme_curve_fitting(adc1_cali_handle);
#elif ADC_CALI_SCHEME_LINE_FITTING_SUPPORTED
adc_cali_delete_scheme_line_fitting(adc1_cali_handle);
#endif
}
}

void app_main(void)
{
// Disable pull-up/pull-down for ADC pins using direct register access
// This is a simpler approach than using gpio_config
gpio_pullup_dis(GPIO_ADC1_CHAN0); // Disable pull-up on GPIO 2
gpio_pulldown_dis(GPIO_ADC1_CHAN0); // Disable pull-down on GPIO 2

gpio_pullup_dis(GPIO_ADC1_CHAN1); // Disable pull-up on GPIO 3
gpio_pulldown_dis(GPIO_ADC1_CHAN1); // Disable pull-down on GPIO 3

ESP_LOGI(TAG, "GPIO pins %d and %d configured with no pull-up/down resistors",
GPIO_ADC1_CHAN0, GPIO_ADC1_CHAN1);

//-------------ADC Calibration Init---------------//
do_calibration = init_adc_calibration();
if (!do_calibration) {
ESP_LOGE(TAG, "Calibration failed to initialize. Using raw ADC readings.");
}

//-------------ADC1 Init---------------//
adc_oneshot_unit_handle_t adc1_handle;
adc_oneshot_unit_init_cfg_t init_config1 = {
.unit_id = ADC_UNIT_1,
};
ESP_ERROR_CHECK(adc_oneshot_new_unit(&init_config1, &adc1_handle));

//-------------ADC1 Config---------------//
adc_oneshot_chan_cfg_t config = {
.atten = EXAMPLE_ADC_ATTEN,
.bitwidth = ADC_BITWIDTH_DEFAULT,
};
ESP_ERROR_CHECK(adc_oneshot_config_channel(adc1_handle, EXAMPLE_ADC1_CHAN0, &config));
ESP_ERROR_CHECK(adc_oneshot_config_channel(adc1_handle, EXAMPLE_ADC1_CHAN1, &config));

// Print confirmation of setup
ESP_LOGI(TAG, "ADC configured with attenuation: %d", EXAMPLE_ADC_ATTEN);

// Main loop for ADC readings
while (1) {
// Read from ADC Channel 2 (GPIO 2)
ESP_ERROR_CHECK(adc_oneshot_read(adc1_handle, EXAMPLE_ADC1_CHAN0, &adc_raw[0]));
ESP_LOGI(TAG, "ADC%d Channel[%d] (GPIO %d) Raw Data: %d",
ADC_UNIT_1 + 1, EXAMPLE_ADC1_CHAN0, GPIO_ADC1_CHAN0, adc_raw[0]);

// Apply calibration if available
if (do_calibration) {
int voltage0 = 0;
ESP_ERROR_CHECK(adc_cali_raw_to_voltage(adc1_cali_handle, adc_raw[0], &voltage0));
ESP_LOGI(TAG, "ADC%d Channel[%d] (GPIO %d) Calibrated Data: %d mV",
ADC_UNIT_1 + 1, EXAMPLE_ADC1_CHAN0, GPIO_ADC1_CHAN0, voltage0);
}
vTaskDelay(pdMS_TO_TICKS(250));

// Read from ADC Channel 3 (GPIO 3)
ESP_ERROR_CHECK(adc_oneshot_read(adc1_handle, EXAMPLE_ADC1_CHAN1, &adc_raw[1]));
ESP_LOGI(TAG, "ADC%d Channel[%d] (GPIO %d) Raw Data: %d",
ADC_UNIT_1 + 1, EXAMPLE_ADC1_CHAN1, GPIO_ADC1_CHAN1, adc_raw[1]);

// Apply calibration if available
if (do_calibration) {
int voltage1 = 0;
ESP_ERROR_CHECK(adc_cali_raw_to_voltage(adc1_cali_handle, adc_raw[1], &voltage1));
ESP_LOGI(TAG, "ADC%d Channel[%d] (GPIO %d) Calibrated Data: %d mV",
ADC_UNIT_1 + 1, EXAMPLE_ADC1_CHAN1, GPIO_ADC1_CHAN1, voltage1);
}
vTaskDelay(pdMS_TO_TICKS(1000));
}

// Note: This teardown code will never be reached due to the infinite loop
ESP_ERROR_CHECK(adc_oneshot_del_unit(adc1_handle));
if (do_calibration) {
deinit_adc_calibration();
}
}