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Return to BlogRS232 to Infrared Interface Converter
Posted Jan 26, 2012 at 9:33 am
Figure 1
An infrared transmit and receive interface has been converted to an RS232 serial interface on this project with the use of a microchip PIC microcontroller.
A sequence of bits modulated as a series of ON/OFF states is possible to be transmitted or received in a 38 KHz infrared carrier signal by sending commands on the RS232 interface. In this device the RS232 refers to waveforms that operate at 5V TTL levels and could destroy the PIC device if it operates at 12V levels but between them, an appropriate converter must be used. A carrier signal that is normally around 38 KHz is used by infrared remote controls which prevent confusion with sunlight radiation frequency. To represent the bit sequences at a lower rate like 500 Hz, the carrier is turned ON and OFF.
The infrared part consists of a transistor that operates as a switch and a capacitor which ensures that sufficient current can be switched to drive the LED. Using the PIC alone to drive the LED would not allow enough current to transmit a strong infrared signal. The operation of the infrared is also shown by a small red LED.
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