The purpose of the project is to monitor the temperature of three compost heaps. It will send the data wirelessly to the receiver and process or display the result to PC. In the transmitter board, the project uses the TXM-433 as RF transmitter and MCU AVR AT90S4433 (you can replace it with AVR ATMEGA8) as main controller. While temperature is sensed using a 10K nominal thermistor.
The uC normally is in an “idle” state. In “idle”, the clock still operates but the rest of the uC is shut down. The clock must run as it is used to calculate the transmit interval, said Don Carveth, the designer .
The main part of receiver is SILRX-433 receiver from Radiometrix. Before connecting to PC, the project uses MAX233 to convert the signal from the RF receiver module to RS-232 . In the PC end software, it use ‘Mailbox’ application, a windows based software written in Visual Basic 5.0 which has purpose read from and write to slave Mailbox uCs using either an RF 5050 protocol or an 8 bit protocol intended for hardwired applications.
Project Detail and Documentation