Midea Air Conditioner Timer

The Midea IR signal uses pulse distance encoding. Each pulse (one “time” unit or 1T) is 21 cycles of a 38KHz carrier burst (about 550µs long). A logic “1” is a 1T pulse followed by a 3T space and takes 2.25ms to transmit. A logic “0” is a 1T pulse followed by a 1T space and takes 1.125ms. The AGC burst consists of a 4.5ms burst followed by 4.5ms space (8T pulse + 8T space). This is very close to the RCA infrared standard. Each byte was first transmitted normal and then inverted for a total of 48 bits of data. This was followed by what appeared to be a single “0” stop bit followed by 4.5ms space (8T). This entire command including the AGC pulse and stop pulse was then immediately transmitted again.

Source: Tom Scheme: link

Download:

AVR Studio GCC Source

Cadsoft Eagle Files

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