- Third generation/revision of project daughterboard
- Using one channel ADC MCP3421 for more compact design
- Side-by-side BME280 for evaluation. Uses I2C address 0x76
- T/RH chips at edge of board for better air-flow
- Thermal barrier for T/RH to minimize heating from other components.
- MS5611 for Pressure is removed and replaced by BME280 on sensornode.
This I2C board uses selected sensors by the WIMEA project. WIMEA-ICT Research Component 3 has focus on Automated Weather Station (AWS) development and network densification in Africa. The work is funded by Norad.
The idea is challenge existing technologies in price performance aspect by using the latest research and products and combining expertise in various fields.
The work herein describes a break-out board with selected sensors to be used as an first approximation for prototyping, verification and testing. The results are open and can be used in various project as well as being a starting point for other. The work includes:
- Sensor selection and testing
- PCB design
- Some comparison
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SHT25 (Sensiron) Temp, RH and via calculation AH, temp dew-point, heat index. http://www.sensirion.com/fileadmin/user_upload/customers/sensirion/Dokumente/Humidity/Sensirion_Humidity_SHT25_Datasheet_V3.pdf
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Optional. BOSH BME280. T/RH/P https://ae-bst.resource.bosch.com/media/_tech/media/datasheets/BST-BMP280-DS001-19.pdf
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MCP3421 (1 channel. Hi-Res 18-bit ΔΣ ADC with Differential Input) http://ww1.microchip.com/downloads/en/DeviceDoc/22003b.pdf
The selected sensors are proposed by Joachim Reuder, Björn Pehrson, Robert Olsson and WIMEA team. Thanks to Andrew Seidl for evaluation of the BME280 pressure sensor.
The break-out board was designed with the gEDA PCB toolchain. Major components gschem and pcb. I2C bus is available on many platforms, Arduino, Raspberry Pi and is available on most microcontrollers. Included:
- gEDA schematics and resource files
- gerber files for fabrication
- various pictures
![Component side] (./pictures/dboard-3-schematics.png)