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FTDI Infrared
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FTDI Infrared
Here is hobby project of building a home-brew IR receiver/transmitter based on the FTDI chipset.
This Project using several IR receivers and transmitters that where based on RS232 connections.
Receiving is the opposite from transmission, and in this case it’s ‘sampling’ the pin at a high enough datarate. The chip will simply sample all pins and put it in it’s fifo buffers. We can read the fifos and inspect the samples.
To make reception reliable I’ve choosen to use a chip which already is tuned to a specific carrier frequency and which outputs the demodulated carrier, so in stead of sampling with 72KHz (see Nyquist: >2x max. freq to be sampled), it is possible to sample with a much lower rate. A lower baudrate will cause less CPU load during reception.
Decoding of the samples can be done relatively easy in software. Detecting a ‘pulse’ or a ‘space’ is a matter of evaluating the received samples and counting the number of samples in-between to get the timing of the pulse and space.
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