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Aosong AHT20/DHT20 – Raspberry Pico SDK port

This is a library for driving the Aosong DHT20/AHT20 sensor, sold by multiple 3rd parties like Adafruit and Seeedstudio. The sensor is connected to using i2c.

The only dependency for this library is pico-sdk, but since it will be imported by whatever project uses this library as a dependency, it's not necessary to add as a submodule separately here.

The library draws some inspiration from Rob Tillaart's library for the Arduino IDE but changes some things to better suit usage with a Raspberry Pi Pico.

An example pico program is provided in DHT20 Pico example repository.

Usage

The port can be easily integrated into a Pico SDK project as a git submodule.

git submodule add https://github.com/sampsapenna/dht20-pico.git
git submodule update

After cloning the repository you need to add the library to CMakeLists.txt used when building the project. Add the following lines before target_link_libraries:

add_subdirectory("dht20-pico")

target_include_directories(dht20 PUBLIC "dht20-pico")
target_link_directories(rgb_lcd PUBLIC "dht20-pico")

Additionally you will need to add the required libraries to linking, by adding hardware_i2c dht20 pico_binary_info to target_link_libraries.

Libary does not initialize i2c, but assumes that program initializes i2c for it. Default initialization, sourced from Raspberry Pi Pico documentation, can look e.g. like this:

    i2c_init(i2c_default, 100 * 1000);
    gpio_set_function(PICO_DEFAULT_I2C_SDA_PIN, GPIO_FUNC_I2C);
    gpio_set_function(PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C);
    gpio_pull_up(PICO_DEFAULT_I2C_SDA_PIN);
    gpio_pull_up(PICO_DEFAULT_I2C_SCL_PIN);
    // Make the I2C pins available to picotool
    bi_decl(bi_2pins_with_func(PICO_DEFAULT_I2C_SDA_PIN, PICO_DEFAULT_I2C_SCL_PIN, GPIO_FUNC_I2C));

Header file to include is DHT20.h, same as in the Arduino library.

Bugs

Sensor has been tested for normal operation. AHT20 has not been tested, but should work just as well as the DHT20 variant, since the only difference between the two is packaging AFAIK.

If you encounter a bug, go ahead and open an issue.