µPD6121, 6122

5

2.

NEC TRANSMISSION FORMAT (REM OUTPUT)

The NEC transmission format consists of the transmission of a leader code, 16-bit custom codes (Custom

Code, Custom Code’), and 16-bit data codes (Data Code, Data Code) at one time, as shown in Figure 2-1.

Also refer to 4. REMOTE OUTPUT WAVEFORM.

Data Code is the inverted code of Data Code.

The leader code consists of a 9-ms carrier waveform and a 4.5-ms OFF waveform and is used as leader for

the ensuing code to facilitate reception detection.

Codes use the PPM (Pulse Position Modulation) method, and the signals “1” and “0” are fixed by the interval

between pulses.

Figure 2-1. REM Output Code

Cautions 1. Use any of the possible 256 kinds of custom codes specified with 00xxH (diode not

connected), as desired. If intending to use custom codes other than 00xxH, please consult

NEC in order to avoid various types of errors from occurring between systems.

2. When receiving data in the NEC transmission format, check that the 32 bits made up of the

16-bit custom code (Custom Code, Custom Code’) and the 16-bit data code (Data Code, Data

Code) are fully decoded, and that there are no signals with the 33rd bit and after (be sure

to check also Data Code).

or

or or or or or or or

Custom Code

Custom Code’

Data Code

Data Code

Leader Code