温度传感器

[English]

简介

ESP32-C61 内置传感器，用于测量芯片内部的温度。该温度传感器模组包含一个 8 位 Sigma-Delta 模拟-数字转换器 (ADC) 和一个数字-模拟转换器 (DAC)，可以补偿测量结果，减少温度测量的误差。

由于硬件限制，温度传感器存在预定义的测量范围及其对应误差，详见下表：

预定义测量范围 (°C)

测量误差 (°C)

50 ~ 125

< 3

20 ~ 100

< 2

-10 ~ 80

< 1

-30 ~ 50

< 2

-40 ~ 20

< 3

备注

温度传感器主要用于测量芯片内部的温度变化。芯片内部温度通常高于环境温度，并且受到微控制器的时钟频率或 I/O 负载、外部散热环境等因素影响。

功能概述

下文将分节概述温度传感器的功能：

资源分配

ESP32-C61 只有一个内置温度传感器硬件。temperature_sensor_handle_t 表示温度传感器模块，该变量也是不同函数之间的纽带。通过使用相同的 temperature_sensor_handle_t 变量，可以在不同的函数调用中访问和修改温度传感器属性，以控制和管理温度传感器。该变量会作为温度 API 的参数，携带有关硬件和配置的信息，你只需创建类型为 temperature_sensor_handle_t 的指针，并将其传递给所需 API。

请在安装内置温度传感器模块前评估测量环境的温度范围。例如，如果在室内测量，环境温度可能在 10 °C ~ 30 °C；如果在灯泡中测量，环境温度则可能在 60 °C ~ 110 °C。在环境温度范围的基础上，请先根据以下值定义配置结构体 temperature_sensor_config_t，再安装内置温度传感器：

  • range_min：所测量温度范围的最小值。

  • range_max：所测量温度范围的最大值。

  • allow_pd 配置驱动程序是否允许系统在睡眠模式下关闭外设电源。在进入睡眠之前，系统将备份温度传感器寄存器上下文，当系统退出睡眠模式时，这些上下文将被恢复。关闭外设可以节省更多功耗，但代价是消耗更多内存来保存寄存器上下文。你需要在功耗和内存消耗之间做权衡。此配置选项依赖于特定的硬件功能，如果在不支持的芯片上启用它，你将看到类似 not able to power down in light sleep 的错误消息。

设置好温度范围后，将配置结构体传递给 temperature_sensor_install()，该函数将创建温度传感器模块并返回句柄。

如前文所述，不同测量范围对应不同测量误差。然而你无需自行比对测量误差，乐鑫提供了一个内部机制，可以根据所给温度范围选择最小误差。

温度传感器使用完毕后，请调用 temperature_sensor_uninstall() 释放相应资源。

创建温度传感器句柄

  • 第 1 步：评估测量范围。本示例的温度范围为 20 °C ~ 50 °C。

  • 第 2 步：配置测量范围，获取温度传感器句柄。

temperature_sensor_handle_t temp_handle = NULL;
temperature_sensor_config_t temp_sensor_config = TEMPERATURE_SENSOR_CONFIG_DEFAULT(20, 50);
ESP_ERROR_CHECK(temperature_sensor_install(&temp_sensor_config, &temp_handle));

启用及禁用温度传感器

  1. 调用 temperature_sensor_enable() 启用温度传感器。此时，内部温度传感器回路开始工作，驱动程序从初始化状态转为启用状态。

  2. 调用 temperature_sensor_disable() 禁用温度传感器。

获取测量的温度值

通过 temperature_sensor_enable() 启用温度传感器后，可以调用 temperature_sensor_get_celsius() 获取当前测量的温度值。

// 启用温度传感器
ESP_ERROR_CHECK(temperature_sensor_enable(temp_handle));
// 获取传输的传感器数据
float tsens_out;
ESP_ERROR_CHECK(temperature_sensor_get_celsius(temp_handle, &tsens_out));
printf("Temperature in %f °C\n", tsens_out);
// 温度传感器使用完毕后，禁用温度传感器，节约功耗
ESP_ERROR_CHECK(temperature_sensor_disable(temp_handle));

安装温度阈值回调函数

ESP32-C61 支持自动触发温度传感器，持续监测内部温度，内部温度达到给定阈值时将触发中断。因此，可以安装中断回调函数执行所需操作，如报警、重启等。下文介绍了如何准备阈值回调函数。

通过参数 user_arg 可以将自定义上下文保存到 temperature_sensor_register_callbacks() 中，用户数据将直接传递给回调函数。

IRAM_ATTR static bool temp_sensor_monitor_cbs(temperature_sensor_handle_t tsens, const temperature_sensor_threshold_event_data_t *edata, void *user_data)
{
    ESP_DRAM_LOGI("tsens", "Temperature value is higher or lower than threshold, value is %d\n...\n\n", edata->celsius_value);
    return false;
}

// 配置回调函数
temperature_sensor_abs_threshold_config_t threshold_cfg = {
    .high_threshold = 50,
    .low_threshold = -10,
};
// 设置监控阈值
temperature_sensor_set_absolute_threshold(temp_sensor, &threshold_cfg);
// 注册中断回调函数
temperature_sensor_event_callbacks_t cbs = {
    .on_threshold = temp_sensor_monitor_cbs,
};
// 安装温度回调函数
temperature_sensor_register_callbacks(temp_sensor, &cbs, NULL);

电源管理

由于温度传感器不使用 APB 时钟，无论是否激活 CONFIG_PM_ENABLE 启用电源管理，温度传感器仍可以继续工作。

IRAM 安全

默认情况下，禁用 cache 时，写入/擦除 flash 等原因将导致温度传感器中断延迟，事件回调函数也将延迟执行。在实时应用程序中，应避免此类情况。

因此，可以启用 Kconfig 选项 CONFIG_TEMP_SENSOR_ISR_IRAM_SAFE，该选项：

  1. 支持在禁用 cache 时启用所需中断

  2. 支持将 ISR 使用的所有函数存放在 IRAM 中

启用该选项可以保证 cache 禁用时的中断运行，但会占用更多的 IRAM。

线程安全

温度传感器中并未添加任何确保线程安全的额外保护，因为温度传感器通常只在一个任务中调用。如果要在不同任务中使用该驱动程序，请设置额外的锁进行保护。

意外情况

  1. 从芯片获取的温度值通常与环境温度不同，因为温度传感器内置于芯片，从某种程度来说，温度传感器测量的是芯片内的温度。

  2. 安装温度传感器失败时，如果驱动程序打印的错误信息为 the boundary you gave cannot meet the range of internal temperature sensor，说明内置温度传感器温度测量范围的限制影响了安装过程，该错误通常由以下几种不正确的 temperature_sensor_config_t 配置造成：

    1. 超出温度测量范围，如 200 °C ~ 300 °C。

    2. 超过了预定义测量范围的界限，如 40 °C ~ 110 °C。

应用示例

API 参考

Header File

  • components/esp_driver_tsens/include/driver/temperature_sensor.h

  • This header file can be included with:

    #include "driver/temperature_sensor.h"

  • This header file is a part of the API provided by the esp_driver_tsens component. To declare that your component depends on esp_driver_tsens, add the following to your CMakeLists.txt:

    REQUIRES esp_driver_tsens

    or

    PRIV_REQUIRES esp_driver_tsens

Functions

esp_err_t temperature_sensor_install(const temperature_sensor_config_t *tsens_config, temperature_sensor_handle_t *ret_tsens)

Install temperature sensor driver.

参数:

  • tsens_config -- Pointer to config structure.

  • ret_tsens -- Return the pointer of temperature sensor handle.

返回:

  • ESP_OK if succeed

esp_err_t temperature_sensor_uninstall(temperature_sensor_handle_t tsens)

Uninstall the temperature sensor driver.

参数:

tsens -- The handle created by temperature_sensor_install().

返回:

  • ESP_OK if succeed.

esp_err_t temperature_sensor_enable(temperature_sensor_handle_t tsens)

Enable the temperature sensor.

参数:

tsens -- The handle created by temperature_sensor_install().

返回:

  • ESP_OK Success

  • ESP_ERR_INVALID_STATE if temperature sensor is enabled already.

esp_err_t temperature_sensor_disable(temperature_sensor_handle_t tsens)

Disable temperature sensor.

参数:

tsens -- The handle created by temperature_sensor_install().

返回:

  • ESP_OK Success

  • ESP_ERR_INVALID_STATE if temperature sensor is not enabled yet.

esp_err_t temperature_sensor_get_celsius(temperature_sensor_handle_t tsens, float *out_celsius)

Read temperature sensor data that is converted to degrees Celsius.

备注

Should not be called from interrupt.

参数:

  • tsens -- The handle created by temperature_sensor_install().

  • out_celsius -- The measure output value.

返回:

  • ESP_OK Success

  • ESP_ERR_INVALID_ARG invalid arguments

  • ESP_ERR_INVALID_STATE Temperature sensor is not enabled yet.

  • ESP_FAIL Parse the sensor data into ambient temperature failed (e.g. out of the range).

esp_err_t temperature_sensor_set_absolute_threshold(temperature_sensor_handle_t tsens, const temperature_sensor_abs_threshold_config_t *abs_cfg)

Set temperature sensor absolute mode automatic monitor.

备注

This function should not be called with temperature_sensor_set_delta_threshold.

参数:
返回:

  • ESP_OK: Set absolute threshold successfully.

  • ESP_ERR_INVALID_STATE: Set absolute threshold failed because of wrong state.

  • ESP_ERR_INVALID_ARG: Set absolute threshold failed because of invalid argument.

esp_err_t temperature_sensor_set_delta_threshold(temperature_sensor_handle_t tsens, const temperature_sensor_delta_threshold_config_t *delta_cfg)

Set temperature sensor differential mode automatic monitor.

备注

This function should not be called with temperature_sensor_set_absolute_threshold

参数:
返回:

  • ESP_OK: Set differential value threshold successfully.

  • ESP_ERR_INVALID_STATE: Set absolute threshold failed because of wrong state.

  • ESP_ERR_INVALID_ARG: Set differential value threshold failed because of invalid argument.

esp_err_t temperature_sensor_register_callbacks(temperature_sensor_handle_t tsens, const temperature_sensor_event_callbacks_t *cbs, void *user_arg)

Install temperature sensor interrupt callback. Temperature sensor interrupt will be enabled at same time.

参数:

  • tsens -- The handle created by temperature_sensor_install().

  • cbs -- Pointer to the group of temperature sensor interrupt callbacks.

  • user_arg -- Callback argument.

返回:

  • ESP_OK: Set event callbacks successfully

  • ESP_ERR_INVALID_ARG: Set event callbacks failed because of invalid argument

  • ESP_FAIL: Set event callbacks failed because of other error

Structures

struct temperature_sensor_config_t

Configuration of measurement range for the temperature sensor.

备注

If you see the log the boundary you gave cannot meet the range of internal temperature sensor. You may need to refer to predefined range listed doc api-reference/peripherals/Temperature sensor.

Public Members

int range_min

the minimum value of the temperature you want to test

int range_max

the maximum value of the temperature you want to test

temperature_sensor_clk_src_t clk_src

the clock source of the temperature sensor.

uint32_t allow_pd

If set, the driver will backup/restore the temperature sensor registers before/after entering/exist sleep mode. By this approach, the system can power off temperature sensor's power domain. This can save power, but at the expense of more RAM being consumed

struct temperature_sensor_config_t flags

Temperature sensor config flags

struct temperature_sensor_threshold_event_data_t

Temperature sensor event data.

Public Members

int celsius_value

Celsius value in interrupt callback.

temperature_val_intr_condition_t intr_condition

Can be used to judge temperature sensor interrupts in which reason

struct temperature_sensor_event_callbacks_t

Group of temperature sensor callback functions, all of them will be run in ISR.

Public Members

temperature_thres_cb_t on_threshold

Temperature value interrupt callback

struct temperature_sensor_abs_threshold_config_t

Config options for temperature value absolute interrupt.

Public Members

float high_threshold

High threshold value(Celsius). Interrupt will be triggered if temperature value is higher than this value

float low_threshold

Low threshold value(Celsius). Interrupt will be triggered if temperature value is lower than this value

struct temperature_sensor_delta_threshold_config_t

Config options for temperature value delta interrupt.

Public Members

float increase_delta

Interrupt will be triggered if the temperature increment of two consecutive samplings if larger than increase_delta

float decrease_delta

Interrupt will be triggered if the temperature decrement of two consecutive samplings if smaller than decrease_delta

Macros

TEMPERATURE_SENSOR_CONFIG_DEFAULT(min, max)

temperature_sensor_config_t default constructor

Type Definitions

typedef struct temperature_sensor_obj_t *temperature_sensor_handle_t

Type of temperature sensor driver handle.

typedef bool (*temperature_thres_cb_t)(temperature_sensor_handle_t tsens, const temperature_sensor_threshold_event_data_t *edata, void *user_data)

Callback for temperature sensor threshold interrupt.

Param tsens:

[in] The handle created by temperature_sensor_install().

Param edata:

[in] temperature sensor event data, fed by driver.

Param user_data:

[in] User data, set in temperature_sensor_register_callbacks().

Return:

Whether a high priority task has been waken up by this function.

Enumerations

enum temperature_val_intr_condition_t

Enum for temperature sensor interrupt condition.

Values:

enumerator TEMPERATURE_VAL_HIGHER_THAN_HIGH_THRESHOLD

temperature sensor value is higher than high threshold

enumerator TEMPERATURE_VAL_LOWER_THAN_LOW_THRESHOLD

temperature sensor value is lower than low threshold

Header File

Type Definitions

typedef soc_periph_temperature_sensor_clk_src_t temperature_sensor_clk_src_t

temperature sensor clock source

Enumerations

enum temperature_sensor_etm_event_type_t

temperature sensor event types enum

Values:

enumerator TEMPERATURE_SENSOR_EVENT_OVER_LIMIT

Temperature sensor over limit event

enumerator TEMPERATURE_SENSOR_EVENT_MAX

Maximum number of temperature sensor events

enum temperature_sensor_etm_task_type_t

temperature sensor task types enum

Values:

enumerator TEMPERATURE_SENSOR_TASK_START

Temperature sensor start task

enumerator TEMPERATURE_SENSOR_TASK_STOP

Temperature sensor stop task

enumerator TEMPERATURE_SENSOR_TASK_MAX

Maximum number of temperature sensor tasks

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