Hitachi air conditioning resolved infrared encoding rules
First, the principle of infrared control air conditioning
Air conditioning remote control is used to transmit information by emitting infrared light off, we can put the time of transmission seen as "1", when not launch seen as "0", so the signal can be transmitted out of turn act as a group of data communication, different keys transmitted at a different encoding. When the air conditioner receives the infrared light in accordance with the rules laid decoder can know what commands sent by the remote control to perform the corresponding operations.
The same brand of air conditioning, their coding rules are the same, so we just find their infrared emission of encoding rules, you can simulate this signal to control the air conditioning all the brand.
Second, the decoding principle
To crack the coding rules, the first to use infrared receiving tube to receive infrared signals sent to the air conditioning, then use an oscilloscope to observe the signal. Air conditioning front IR codes generally have at least a boot code, a specific time is low and the high level of composition, do not know the students can go to check the NEC rules. Then data is then transmitted to the general data "0" and "1" is a composition of high a low + a, but the level is not the same time, different brands of air conditioning, "0" and " 1 "high and low time there are differences. Well, then know this information, you can use the microcontroller to capture these levels, and by collecting the duration of each level you can know the transmission data is "0" or "1", and then through the serial port printed on it to obtain a complete frame of data. Then measure multiple sets of data by changing certain variables, find out the law can change that part of the launch of the encoding rules.
Third, the level rules
A first boot code: Low about 30ms, about 50ms high
second preamble: low 3-3.5ms, high 1.5-2ms
data 0: low 350-400us, high about 450us
data 1: low 350-400us, the high level of about 1300us
Note: the duration of these there is a certain level of fault tolerance space, so not necessarily in strict accordance with this value to transmit infrared signals, if you find press these values can not control the air conditioning, the edges can be corrected on the basis of this value, to try always to find the right value.
Fourth, the encoding rules
状态：关机->制冷/制热/除湿：1000
制冷/制热/除湿->关机：0100
风速切换：0011
温度加：0001
温度减：1001
PS：一般的空调都没有这个状态位，直接用一个开关机位就行了，不知道搞这个有什么意义
模式：制热110 制冷001 除湿101
风速：微110 弱001 强101 自动100
温度：（温度-16）（逆序）
如：24度 = （24 - 16）（逆序） = 1000（逆序）= 0001
开关：开1 关0
校验 = [ 56（即7左移4位）- 温度逆序值*2 - 模式逆序 - 风速逆序 - 状态逆序 + 开关取反左移8位 ]（逆序）
如：关机 -> 制冷17度 风速自动
校验 = [ 56 - 2 - 4 - 1 - 1 + 0 ]（逆序）= 48（逆序）=（00110000）（逆序）= 00001100
制冷17度 风速自动 -> 关机
校验 = [ 56 - 2 - 4 - 1 - 2 + 128 ]（逆序）= 175（逆序）=（10101111）（逆序）=11110101
PS：这个校验的公式可能不止一种，我推出来的这个不一定是原厂的公式，你们有兴趣可以去研究一下。
Note: regular boot, the sleep timer off, and I do not need the project, it did not go to law, the timer switch according to my experience should be respectively represented by 8 bits, the check is likely to be in front of the this part, interested students can go and find me follow this method. In addition to checking the rest of the code should be better than to find the law, as this verification check ... Oh ... I spent a lot of my time to break, because there is a status bit strange, but I put in front of the check launch a rule, together with the timer switch back should not be difficult.
Well, on the value of Hitachi Air Conditioning code will stop here, if you have any questions, you can leave a message to me, if the article is wrong, be sure to point it out, if this post is just to help you can give me a praise ,Thank you! ! !
