HTU21D temperature and humidity sensor example for theCore embedded C++ framework

Detailed description

HTU21D example shows how to read humidity and temperature samples using theCore. See theCore documentation for HTU21D example for more information.

Supported targets (boards)

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

Wiring

STM32F4 Discovery 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 https://forgge.github.io/theCore/faq.html#how-to-check-stm32f4-discovery-board-revision.html

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%