HTU21D temperature and humidity sensor example

Location:https://github.com/theCore-embedded/example_sensor_htu21d
Target:STM32F4 Discovery board
External HW:UART-to-USB converter attached to the USART2, HTU21D sensor

HTU21D example shows how to read humidity and temperature samples using theCore. For more information about what this sensor does see the HTU21D humidity and temperature sensor page.

Supported targets (boards)

Target name Configuration file Description
stm32f4_disc stm32f4_discovery.json STM32F4 discovery board

Wiring

STM32F4 Discovery board

UART and HTU21D example wiring for stm32f4discovery board

  1. Connect HTU21D to I2C1 on the Discovery board using following pins:

    PB6 (I2C1 SCL) sensor’s SCL
    PB9 (I2C1 SDA) sensor’s SDA
    +3.3V sensor’s VDD
    GND sensor’s GND

  2. Attach any preferable UART-to-USB converter such as this module according to following pinout:

    PD8 (USART3 TX) module’s RX
    PD9 (USART3 RX) module’s TX
    GND module’s GND

Preparing

  1. Install and initialize theCore (if not done previously):

    pip3 install tcore
# Or if python3-pip is default: pip install tcore
tcore bootstrap

  2. Download the example:

    tcore init --remote https://github.com/theCore-embedded/example_sensor_htu21d
cd example_sensor_htu21d

Building

Run compile command using theCore CLI:

tcore compile --target stm32f4_disc

Running

Firmware will be flashed via openocd debugger and flash command.

  1. Connect stm32f4 Discovery board to USB cable and connect USB <-> UART converter to the PC.

  2. Launch minicom with device associated with USB <-> UART converter. (/dev/ttyUSB0 here used as an example):

    # From new terminal
tcore runenv "minicom -D /dev/ttyUSB0"

    Or the same, but with superuser permissions:

    # From new terminal
tcore runenv --sudo "minicom -D /dev/ttyUSB0"

  3. Determine stm32f4discovery board revision.

    If you don’t remember your board revision, check FAQ section How to check STM32F4 Discovery board revision?.

  4. Launch flash command in separate terminal, as shown below.

    For old STM32F407G-DISC boards, with STLINK/V2:

    tcore flash --sudo

    For new STM32F407G-DISC1 boards, with STLINK/V2.1:

    tcore flash --sudo --debugger-config stlink-v2.1

Expected output

Observe console output in the minicom:

Welcome to theCore
the_core v0.3.0.321 90f4894-dirty
Starting HTU21D sensor...
Reset done
Temperature: 25.362 Celsius   Humidity: 45.162%
Temperature: 25.362 Celsius   Humidity: 45.170%
Temperature: 25.362 Celsius   Humidity: 45.155%
Temperature: 25.362 Celsius   Humidity: 45.147%
Temperature: 25.351 Celsius   Humidity: 45.155%