esp-idf/components/driver/esp32c3/rtc_tempsensor.c

/*
 * SPDX-FileCopyrightText: 2016-2021 Espressif Systems (Shanghai) CO LTD
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <esp_types.h>
#include <stdlib.h>
#include <ctype.h>
#include <math.h>
#include "freertos/FreeRTOS.h"
#include "freertos/semphr.h"
#include "esp_log.h"
#include "esp_check.h"
#include "hal/adc_ll.h"
#include "soc/rtc_cntl_reg.h"
#include "soc/apb_saradc_struct.h"
#include "soc/apb_saradc_reg.h"
#include "soc/system_reg.h"
#include "driver/temp_sensor.h"
#include "regi2c_ctrl.h"
#include "esp32c3/rom/ets_sys.h"
#include "esp_efuse_rtc_calib.h"

static const char *TAG = "tsens";

#define TSENS_XPD_WAIT_DEFAULT 0xFF   /* Set wait cycle time(8MHz) from power up to reset enable. */
#define TSENS_ADC_FACTOR  (0.4386)
#define TSENS_DAC_FACTOR  (27.88)
#define TSENS_SYS_OFFSET  (20.52)

typedef struct {
    int index;
    int offset;
    int set_val;
    int range_min;
    int range_max;
    int error_max;
} tsens_dac_offset_t;

static const tsens_dac_offset_t dac_offset[TSENS_DAC_MAX] = {
    /*     DAC     Offset reg_val  min  max  error */
    {TSENS_DAC_L0,   -2,     5,    50,  125,   3},
    {TSENS_DAC_L1,   -1,     7,    20,  100,   2},
    {TSENS_DAC_L2,    0,    15,   -10,   80,   1},
    {TSENS_DAC_L3,    1,    11,   -30,   50,   2},
    {TSENS_DAC_L4,    2,    10,   -40,   20,   3},
};

typedef enum {
    TSENS_HW_STATE_UNCONFIGURED,
    TSENS_HW_STATE_CONFIGURED,
    TSENS_HW_STATE_STARTED,
} tsens_hw_state_t;

static tsens_hw_state_t tsens_hw_state = TSENS_HW_STATE_UNCONFIGURED;

static float s_deltaT = NAN; // unused number

esp_err_t temp_sensor_set_config(temp_sensor_config_t tsens)
{
    if (tsens_hw_state == TSENS_HW_STATE_STARTED) {
        ESP_LOGE(TAG, "Do not configure the temp sensor when it's running!");
        return ESP_ERR_INVALID_STATE;
    }
    REG_SET_BIT(SYSTEM_PERIP_CLK_EN1_REG, SYSTEM_TSENS_CLK_EN);
    CLEAR_PERI_REG_MASK(ANA_CONFIG_REG, ANA_I2C_SAR_FORCE_PD);
    SET_PERI_REG_MASK(ANA_CONFIG2_REG, ANA_I2C_SAR_FORCE_PU);
    REGI2C_WRITE_MASK(I2C_SAR_ADC, I2C_SARADC_TSENS_DAC, dac_offset[tsens.dac_offset].set_val);
    APB_SARADC.apb_tsens_ctrl.tsens_clk_div = tsens.clk_div;
    APB_SARADC.apb_tsens_ctrl2.tsens_xpd_wait = TSENS_XPD_WAIT_DEFAULT;
    APB_SARADC.apb_tsens_ctrl2.tsens_xpd_force = 1;
    ESP_LOGD(TAG, "Config temperature range [%d°C ~ %d°C], error < %d°C",
             dac_offset[tsens.dac_offset].range_min,
             dac_offset[tsens.dac_offset].range_max,
             dac_offset[tsens.dac_offset].error_max);
    tsens_hw_state = TSENS_HW_STATE_CONFIGURED;
    return ESP_OK;
}

esp_err_t temp_sensor_get_config(temp_sensor_config_t *tsens)
{
    ESP_RETURN_ON_FALSE(tsens != NULL, ESP_ERR_INVALID_ARG, TAG, "no tsens specified");
    CLEAR_PERI_REG_MASK(ANA_CONFIG_REG, ANA_I2C_SAR_FORCE_PD);
    SET_PERI_REG_MASK(ANA_CONFIG2_REG, ANA_I2C_SAR_FORCE_PU);
    tsens->dac_offset = REGI2C_READ_MASK(I2C_SAR_ADC, I2C_SARADC_TSENS_DAC);
    for (int i = TSENS_DAC_L0; i < TSENS_DAC_MAX; i++) {
        if (tsens->dac_offset == dac_offset[i].set_val) {
            tsens->dac_offset = dac_offset[i].index;
            break;
        }
    }
    tsens->clk_div = APB_SARADC.apb_tsens_ctrl.tsens_clk_div;
    return ESP_OK;
}

esp_err_t temp_sensor_start(void)
{
    if (tsens_hw_state != TSENS_HW_STATE_CONFIGURED) {
        ESP_LOGE(TAG, "Temperature sensor is already running or not be configured");
        return ESP_ERR_INVALID_STATE;
    }
    REG_SET_BIT(SYSTEM_PERIP_CLK_EN1_REG, SYSTEM_TSENS_CLK_EN);
    APB_SARADC.apb_tsens_ctrl2.tsens_clk_sel = 1;
    APB_SARADC.apb_tsens_ctrl.tsens_pu = 1;
    tsens_hw_state = TSENS_HW_STATE_STARTED;
    return ESP_OK;
}

esp_err_t temp_sensor_stop(void)
{
    APB_SARADC.apb_tsens_ctrl.tsens_pu = 0;
    APB_SARADC.apb_tsens_ctrl2.tsens_clk_sel = 0;
    return ESP_OK;
}

esp_err_t temp_sensor_read_raw(uint32_t *tsens_out)
{
    ESP_RETURN_ON_FALSE(tsens_out != NULL, ESP_ERR_INVALID_ARG, TAG, "no tsens_out specified");
    *tsens_out = APB_SARADC.apb_tsens_ctrl.tsens_out;
    return ESP_OK;
}

static void read_delta_t_from_efuse(void)
{
    uint32_t version = esp_efuse_rtc_calib_get_ver();
    if (version == 1) {
        // fetch calibration value for temp sensor from eFuse
        s_deltaT = esp_efuse_rtc_calib_get_cal_temp(version);
    } else {
        // no value to fetch, use 0.
        s_deltaT = 0;
    }
    ESP_LOGD(TAG, "s_deltaT = %f", s_deltaT);
}

static float parse_temp_sensor_raw_value(uint32_t tsens_raw, const int dac_offset)
{
    if (isnan(s_deltaT)) { //suggests that the value is not initialized
        read_delta_t_from_efuse();
    }
    float result = (TSENS_ADC_FACTOR * (float)tsens_raw - TSENS_DAC_FACTOR * dac_offset - TSENS_SYS_OFFSET) - s_deltaT / 10.0;
    return result;
}

esp_err_t temp_sensor_read_celsius(float *celsius)
{
    ESP_RETURN_ON_FALSE(celsius != NULL, ESP_ERR_INVALID_ARG, TAG, "celsius points to nothing");
    temp_sensor_config_t tsens;
    uint32_t tsens_out = 0;
    esp_err_t ret = temp_sensor_get_config(&tsens);
    if (ret == ESP_OK) {
        ret = temp_sensor_read_raw(&tsens_out);
        ESP_LOGV(TAG, "tsens_out %d", tsens_out);
        ESP_RETURN_ON_FALSE(ret == ESP_OK, ret, TAG, "failed to read raw data");
        const tsens_dac_offset_t *dac = &dac_offset[tsens.dac_offset];
        *celsius = parse_temp_sensor_raw_value(tsens_out, dac->offset);
        if (*celsius < dac->range_min || *celsius > dac->range_max) {
            ESP_LOGW(TAG, "Exceeding the temperature range!");
            ret = ESP_ERR_INVALID_STATE;
        }
    }
    return ret;
}