IR remote control
From Teknologisk videncenter
IRP Notation
RC5 Example
- UEI protocol: 00E8
- IRP notation: {36k,msb,889}<1,-1|-1,1>(1:1,~F:1:6,T:1,D:5,F:6,^114m)+
- EFC translation: 6-bit MSB comp with 2-bit mini-combo
The first section {36k,msb,889} is called the GeneralSpec section and describes the carrier frequency order of transmission and the manchester bit slot time length.
- 36k defines 36KHz modulation of the infrared light with a 50/50 duty cycle
- msb defines the most significant bit is transmitted first
- 889 defines the slottime is 889uS.
The next section <1,-1|-1,1> is called the bitspec and specifies the rules for translating a bit sequence into a IR signal
- 1,-1 means "0" is transmitted as a IR on for one slottime and off for one slottime
- -1,1 means "1" is transmitted as a IR off for one slottime and on for one slottime
The next section (1:1,~F:1:6,T:1,D:5,F:6,^114m)+ is called the bitfield section and describes the
| Section | Bit | value | Explanation |
|---|---|---|---|
| 1:1 | 1 | 1 | defines one startbit as a binary 1. First bit |
| ~F:1:6 | 2 | 0 or 1 | ~ means complement bit(s), F is from the function field, 1:6 means transmit 1 bit after the first 6 bit. Meaning transmit the complementet bit 7 of the F field. This extends the F field from 6 to 7 bits on some transmitters |
| T:1 | 3 | 0 or 1 | Transmit one toggle bit. A control bit, which toggles with each button press. his allows the receiving device to distinguish between two successive button presses (such as "6", "6" for "66") as opposed to the user simply holding down the button and the repeating commands being interrupted by a person walking by, for example. |
| D:5 | 4 to 8 | 0 to 31 | A five bit system address to select device for example TV |
| F:6 | 9 to 14 | 0 to 63 | A six bit command combined with the T:1 toggle bit giving 7 bit command 0 to 127. |
| ^114m)+ | - | - | Trailing gap 114 mSec. With auto repeat repeats every 114 mSec. |