RC5 infrared format

The format is: start bit (1 bit) + verification bit (1 bit) + control bit (1 bit) + system code (5 bits) + command bit (6 bits).

There are 14 data in total, and the definition of each of them is as follows:

â‘´START BIT: The first bit is fixed to logic '1'. Take up one.

⑵INDITICATION BIT: Occupy one bit. If the verification bit is logic '1', the command bit (COMMAND BITS) indicates 0 ~ 63, which is the original RC5 system; if the verification bit is logic '0', the command bit (COMMAND BITS) indicates 64 ~ 127. This is an extended RC5 system.

⑶CONTROL BIT: Used to distinguish whether a new key is pressed. If a new key is pressed, this bit changes once (1à0 or 0à1). Take up one. (See Figure RC5-1 and Figure RC5-2 CONTROL BIT section).

â‘·SYSTEM BITS. The next 5 digits indicate the type of device to be controlled, such as TV, VCR, TUNER, etc. Take up five.

⑸ Command bit (COMMAND BITS). The last six digits represent the key value.

3.1.2 Logical definition of data

(1) Definition of RC5 logic level (for received data).

Logic '1': high to low first, falling edge.

Logic '0': low first, then high, rising edge.

The data sent is the inverse of the received.

(2) Time for each bit of RC5

RC5 uses a 36K carrier, and the half-bit time (1T) occupies 32 carrier cycles

Half time (HALF BIT TIMEà1T): 32 * 27778 = 888.889μs (1T)

One bit time (FULL BIT TIMEà 2T): 2 * 888.889 = 1777.778μs (2T)

(3) RC5 message elapsed time (MESSAGE TIME) and one frame (FRAME TIME)

A message contains 14 bits, so the message time is: 14 * 1777.778 = 24.889MS (28T).

A frame contains 15.5 bits, so the frame time is: 15.5 * 1777.778 = 27.556MS (31T).

(4) RC5 repeating time (REPEATING TIMING)

112.4ms.