PIC Microcontroller Based Wireless Temperature and Heart Beat Read-Out

MUDIT AGARWAL
Microcontroller Based Wireless Temperature And
HeartBeat Read Out suitable for operation in a
small office/home environment. This system is easy
to operate, with Visual LCD. Many individuals and
organizations may, for various reasons, wish to use
electronic surveillance techniques at some time or
another. The 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. This 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 Heat Beat format.






Temperature Sensors
Temperature is one of the fundamental physical
variables in most chemical and process control
applications. Accurate and reliable measurement
of the temperature is important in nearly all process
control applications. Temperature sensors can be
analog or digital. Some of the most commonly used
analog temperature sensors are: thermocouples,
resistance temperature detectors (RTDs) and
thermistors. Digital sensors are in the form of
integrated circuits. The choice of a sensor depends
on the accuracy, the temperature range, speed of
response, thermal coupling, the environment
(chemical, electrical, or physical) and the cost. A
popular voltage output analog integrated circuit
temperature sensor is the LM35DZ, manufactured
by National Semiconductor. This is a 3-pin analog
output sensor which provides a linear output
0 voltage of 10 mV/ C. The temperature range is 0
0 0 0 C to +100 C, with an accuracy of ±1.5 C.