Microcontroller based wireless temperature and heartbeat read out suitable for a operation in a small office/home environment . This system is suitable to operate with Visual LCD. Many individuals or organisations may, for various reasons,wish to use electronic surveillance technique at some time or another. This idea is to use off the shelf RF Tx/Rx modules. The weather keeps us continually occupied. Some people have even made it their profession. At home too,we like to measure all kinds of things related to our climate.That is why weather stations are available in all types and sizes.
If we want to know the temperature inside and outside then purpose built indoor/outdoor thermometers are available. In the past the outside sensor of these weather stations was connected with a wire, it is now fairly standard to use RF transmission for this data. The wireless transmitters units usually make use of the 315-MHz band. These modules, once a rare commodity, are now widely and cheaply available. In this particular discussion, we shall be using ASK(Amplitude Shift Keying) based TX/RX pair operating at 315 MHz. The transmitter module accepts serial data at a maximum of 2400bps. They are directly interfaced to a microcontroller. At the RX end, the receiver microcontroller receives the signal via the RF receiver module,decodes the serial data and reproduces the original data in the temperature and Heart Beat format.
The choice of a sensor depends on the accuracy, the temperature range, speed of response, thermal coupling, the environment (chemical, electrical, physical) and the cost. A popular voltage output analog integrated circuit temperature sensor is LM35DZ,manufactured by National Semiconductor. This is the 3 pin analog output sensor which provides a linear output voltage of 10 mV/degree Celsius. The temperature range is 0 to 100 degree Celsius, with an accuracy of +-1.5 degree Celsius.