xref: /docs/en/device-dev/subsystems/subsys-power-temperature-protection.md

# Battery Temperature Protection Customization

## Overview

### Introduction

OpenHarmony provides battery temperature protection by default. When a device is used in different environments, the battery temperature may become excessively high or low due to the impact of ambient environment. In such a case, the protection measures, for example, device shutdown, must be taken to ensure the device safety. However, the supported temperature range varies according to products. To address this issue, OpenHarmony provides the function of customizing the temperature range for battery protection.

### Constraints

The configuration path for battery level customization is subject to the [configuration policy](https://gitee.com/openharmony/customization_config_policy). In this development guide, `/vendor` is used as an example of the configuration path. During actual development, you need to modify the customization path based on the product configuration policy.

## How to Develop

### Setting Up the Environment

**Hardware requirements:**

Development board running the standard system, for example, the DAYU200 or Hi3516D V300 open source suite.

**Environment requirements:**

For details about the requirements on the Linux environment, see [Quick Start](../quick-start/quickstart-overview.md).

### Getting Started with Development
The following uses [DAYU200](https://gitee.com/openharmony/vendor_hihope/tree/master/rk3568) as an example to illustrate charging type customization.

1. Create the battery folder in the product directory [/vendor/hihope/rk3568](https://gitee.com/openharmony/vendor_hihope/tree/master/rk3568).

2. Create a target folder by referring to the [default folder of power temperature projection configuration](https://gitee.com/openharmony/powermgr_battery_manager/tree/master/services/native/profile), and install it in `//vendor/hihope/rk3568/battery`. The content is as follows:

    ```text
    profile
    ├── BUILD.gn
    ├── battery_config.json
    ```

3. Write the custom `battery_config.json` file by referring to the `battery_config.json` file in the default folder of power temperature projection configuration. For example:

    ```json
    {
        "temperature": {
        "high": 500,
        "low": -400
        }
    }
    ``` 

    **Table 1** Description of temperature protection configuration
    | Temperature Protection Threshold| Temperature (°C)|
    | -------- | -------- |
    | high | 600 |
    | low | -500 |


4. Write the `BUILD.gn` file by referring to the `BUILD.gn` in the default folder of power temperature projection configuration to pack the `battery_config.json` file to the `//vendor/etc/battery` directory. The configuration is as follows:

    ```shell
    import("//build/ohos.gni")                # Reference build/ohos.gni.

    ohos_prebuilt_etc("battery_config") {
        source = "battery_config.json"
        relative_install_dir = "battery"
        install_images = [ chipset_base_dir ] # Required configuration for installing the battery_config.json file in the vendor directory.
        part_name = "product_rk3568"          # Set part_name to product_rk3568 for subsequent build.
    }
    ```

5. Add the build target to `module_list` in [ohos.build](https://gitee.com/openharmony/vendor_hihope/blob/master/rk3568/ohos.build) in the `/vendor/hihope/rk3568` directory. For example:

    ```json
    {
    "parts": {
        "product_rk3568": {
        "module_list": [
            "//vendor/hihope/rk3568/default_app_config:default_app_config",
            "//vendor/hihope/rk3568/image_conf:custom_image_conf",
            "//vendor/hihope/rk3568/preinstall-config:preinstall-config",
            "//vendor/hihope/rk3568/resourceschedule:resourceschedule",
            "//vendor/hihope/rk3568/etc:product_etc_conf",
            "//vendor/hihope/rk3568/battery/profile:battery_config" # Add the configuration for building of battery_config.
        ]
        }
    },
    "subsystem": "product_hihope"
    }
    ```
    In the preceding code, `//vendor/hihope/rk3568/battery/` is the folder path, `profile` is the folder name, and `battery_config` is the build target.

6. Build the customized version by referring to [Quick Start](../quick-start/quickstart-overview.md).

    ```shell
    ./build.sh --product-name rk3568 --ccache
    ```

7. Burn the customized version to the DAYU200 development board.

### Debugging and Verification

1. After startup, run the following command to launch the shell command line:
    ```
    hdc shell
    ```

2. Go to the custom battery temperature configuration directory. The path of DAYU200 is used as an example.
    ```
    cd /data/service/el0/battery/battery
    ```

3. Modify the battery temperature. The following uses the default power temperature protection configuration as an example.

    ```
    echo 700 > temp
    ```
4. Report the battery information change to trigger temperature protection.
    ```
    hidumper -s 3302 -a -r
    ```
    The device is powered off.

5. Upon restarting, launch the shell command line, and modify the battery temperature.
    ```
    echo -600 > temp
    ```
6. Report the battery information change to trigger temperature protection.
    ```
    hidumper -s 3302 -a -r
    ```
    The device is powered off.

7. Customize the temperature protection threshold configuration. For example:

    ```json
    {
        "temperature": {
        "high": 500,
        "low": -400
        }
    }
    ```

8. Modify the temperature protection threshold. 
    ```
    echo 550 > temp
    ```

9. Report the battery information change to trigger temperature protection.
    ```
    hidumper -s 3302 -a -r
    ```
    The device is powered off.

10. Upon restarting, launch the shell command line, and modify the temperature protection threshold.
    ```
    echo -450 > temp
    ```

11. Report the battery information change to trigger temperature protection.
    ```
    hidumper -s 3302 -a -r
    ```
    The device is powered off.

## Reference
During development, you can refer to the [default power temperature protection configuration](https://gitee.com/openharmony/powermgr_battery_manager/tree/master/services/native/profile/), as shown below:

```json
{
    "temperature": {
    "high": 600,
    "low": -500
    }
}
```
Packing path: `/system/etc/battery`