GCBASIC documentation
Infrared Remote Control

Syntax:

    NECSend address, data

    NECByte value

Command Availability:

Available on all microcontrollers. Requires the inclusion of the following:

    #include <remote.h>

Explanation:

NECSend transmits a complete NEC-protocol infrared remote-control frame: a start burst, a sync gap, the address byte, its bitwise complement, the command byte, and its complement. NECByte is the lower-level routine NECSend uses to transmit each of those four bytes individually — most programs only need to call NECSend.

Both this command and RC5Send (see RC5 Remote Control) share the same output pin, set with:

    #define RC5Out <pin>

address and data are byte values. NECSend automatically transmits each one’s bitwise complement (!address, !data) immediately afterward, which is how a NEC receiver detects transmission errors.

Each bit sent by NECByte is a short mark burst followed by a space whose length encodes the bit value — the two space lengths differ so a receiver can distinguish a 1 from a 0.

Example:

    #chip 16F877A, 20

    #define RC5Out PORTB.0
    Dir RC5Out Out

    Do
        NECSend 0x04, 0x0A          ' <<< the NECSend instruction
        Wait 100 ms
    Loop

Key line: NECSend 0x04, 0x0A — transmits address 0x04 and command 0x0A as a complete NEC frame (address, its complement, command, its complement), preceded by the standard start burst and sync gap.

See Also: