I am reverse engineering IR protocol of LG air conditioner. AC generally send the whole current state of remote on each key press. Data sent is 28 bits long, last 4 bits seem to be the checksum. I have already tried reveng
, but without luck.
Bits 14-16 are mode of operation (heat/cool/fan/auto). Bits 17-20 are temperature + 15 degrees, bits 22-24 are fan speed and bits 25-28 seem to be 4-bit checksum.
Here are sample values:
100010000000100001000101 0001
100010000000100001010101 0010
100010000000100001100101 0011
100010000000100010000100 0100
100010000000100011000101 1001
100010000000100011010101 1010
100010000000100011110101 1100
100010000000000011000101 0001
100010001100000000000101 0001
In the last two, only the position of 11
changed, but checksum stayed the same. How is that checksum calculated?