Schematic Overview
Two circuits need to be built for this tutorial; the transmitter and the
receiver. These two circuits are not over-complex in anyway so hopefully
acquiring the parts and assembling everything should be straight forward. The
main parts to take note of in these two circuits are the
7805,
18F452,
2N2222,
Phototransistor and
IR Emitter LED.
Wireless Infrared Link
Transmitter Schematic
View Full Schematic
Schematic Specifics
Power Circuit
The power circuit (regulator) is the same in both transmitter and receiver
because all we need a +5v regulated power supply to operate the digital
electronics. The 7805 linear regulator was chosen because it is cheap and widely
available.
Microcontroller Circuit
The transmitting microcontroller will be a PIC 18F452. The USART module
inside of this microcontroller will be used to send the asynchronous serial
data. The microcontroller will continuously send a count value from 0 to 8 and
then repeat.
Infrared Transmitter Circuit
The PIC's digital USART RC6 Tx output port cannot supply enough current to
give the IR emitter LED the power it really needs, so a buffer circuit is used
with 2x 2N2222 transistors so that the IR Emitter LED is driven from the main
+5v regulated power supply.
Wireless Infrared Link Receiver
Schematic
View Full Schematic
Schematic Specifics
Power Circuit
The power circuit (regulator) is the same in both transmitter and receiver
because all we need a +5v regulated power supply to operate the digital
electronics. The 7805 linear regulator was chosen because it is cheap and widely
available.
Microcontroller Circuit
To make things as simple as possible, the receiving microcontroller will be the
same as the transmitter: PIC 18F452. The other half of the USART module will be
used to receive the data, rather than transmit and then the PIC will decide how
many LEDs to light up, 0 to 8, depending upon the transmitted ASCII value, 0 to
8.
Infrared Receiving Circuit
This circuit consists of a photo transistor and 1x 10kΩ resistor with some
connections to ground and power. The collector pin of the phototransistor is
connected to the PIC's RC7 input also known as the USART Rx input.
|
