Wireless remote control technology is also widely used in security systems, such as parking lot system in the gate remote control, access control wireless remote control door remote control, wireless alarm system and so on. At present, the mainstream wireless remote control codec chip on the market, welding code, learning code, rolling code. According to the address code of emitter, welding code and learning code belong to fixed code. The coding chip of wireless remote controller used in security system is mainly welding code and learning code.
Welding code: it is composed of 8 different address codes, mainly using PT, SC, HS, LX (2260/2262/2264) and other coding IC chips. Before using, welding code is required for the address pin of the coding IC. The address code has three welding states (high level, low level, suspended). So 3 to the eighth, 6561 possible combinations. The paired receiving and decoding chips are PT, SC, LX, HS (2270/2272/2294), etc., one receiving end can be equipped with several, dozens, hundreds of wireless remote controls. It is often used for gate remote control, telescopic door remote control, rolling shutter door remote control, wireless remote control lamp switch, etc. Advantages: stable, disadvantages: insecure, easy to duplicate, and easy to copy.
Learning code: the wireless remote controller mainly adopts EV, HS, LX, SC (1527/2240), HCS101 and other learning code chips. Before use, the wireless remote controller needs to be aimed at the learning button on the host for code learning, without breaking the shell and coding. The address bit combination of the learning code wireless remote controller is 2 ^ 20, that is 1048576, which is about one million combinations. Compared with welding code weight rate and security is relatively good. The paired receiver is the host with program storage IC, MCU, such as PIC16F630, PIC16F505, PIC16F629, etc.
Fixed codes are still relatively insecure because they have a limited number of codes and therefore only a limited number of code combinations, which can be easily obtained by aerial capture and scanning-tracking, which can be used by unauthorized users. Then came the scroll code.
Rolling code: the use of a longer coding mode, when the key input, the system from the power saving state wake up, synchronization count plus 1, with the serial number through the key encryption after the formation of ciphertext data, and with key values and other data sent out. Since the synchrometer values are sent differently each time, even if the same key is pressed multiple times. The synchronization count scrolls forward automatically and the code word sent does not occur again, hence it is called a scroll code.
Rolling code remote control confidentiality is better, currently more and more widely used, especially high security requirements of the system, generally used for identity authentication scenarios, such as car remote control, bank wireless door lock, etc.. Special integrated chips for rolling code include HCS200, HCS300, HCS301, etc.