Controlled by ATmega8A Atmel datasheet *.pdf CPU. CPU reads sensors and send data to PC via serial interface (RS-232 , 9600 bod). PCB board was developed in size which allow further installation into the Gainta G-203CMF Gainta datasheet *.pdf housing. Current weather station could measure the next parameters:
- Pressure (BMP085) 225…826 mm.Hg.
- Temperature (DS18B20, DHT22, BMP085) -50…+50°С
- Humidity (DHT22/AM2302) 0…99%
Pressure sensor BMP085 was purchased as ready to use module GY-65. In the device also used CP2102 USB-serial converter module. All sensor connected to the main board according the common connection schemes which could be found into the datasheets for these components (datasheets list see in the bottom of this post). Firmware was written with help of ready code examples for next sensors: BMP085 (radiokot.ru), DHT22/AM2302 (radiokot.ru). Firmware was written in the Codevision for AVR IDE. Codevision project compiled for internal 4MHz clock source.
When board is connected to the PC it starts to send lines with sensor reading (see example of reading on the left). Data separates with commas for make further processing more easier. Data order is next: char # – beginning of the line, pressure (mm.Hg), temperature (DS18B20), temperature (DHT22/AM2302), \n – end of the line.
Also on the board I have made the high voltage DC-DC converter 5->400V with detector circuit for supplying Geiger tubes. But in the current version of firmware this option is not included.