The RC5 protocol

I - THEORIC SIDE

1) The complete frame

It is the result of 14 patterns spread into 4 blocks like this:

with ?=0 or 1 for the pattern value (depends on the block to transmit).

 

2) Meaning of the blocks

START:With the block control, this block mark the start of a frame and be sure it is not due to perturbations
CONTROL:When we go on pressing a Key on a remote, this pattern toggles 0-1-0-1..By this way, the receiver adapts its sensibility by taking into account the level of the batteries of your RC
SYSTEM:Define the system to control TV, CD player,...
COMMAND:Describes the action to do on this system STOP,PAUSE,PLAY...

The values SYSTEM and COMMAND are normalized. Click on the links to discover the meaning of each value blocks..

3) Basic patterns

Here are the elementary and repetitive pieces of the electric signal :

• representing either 0 or 1 , the value of the pattern.
• forming the whole frame.

Pattern	ST0, ST1	CT0		S4 à S0		C5 à C0
Possible Value	1	0	1	0	1	0	1
Representation

Warning, the glue between each pattern is not shown here.

4) The dynamic model

Difficulties to understand? then look at this. The datas (or several control fields, ie not constant) of the frame are located in the patterns of the frame that can be changed. These are represented for you by buttons you can manipulate. The value on the buton is either the value of a block (see the meaning in paragraph 2 ) or the value of the pattern. Click on the buttons , observe , et analyze what happens on the electric signal..

• if the frame is

• then electricaly , the signal will be:

 

Try now do do the inverse : take one electric signal , deduce the value transmitted for each pattern you see, calculate each bloc value and guess what action is triggered. Click on one or more pattern on the signal and you will get the answer! If you let your mouse cursor on one pattern, you will even get its name.

• and will
  
  
  trigger on your the action

Now suppose that I receive a frame containing the following pattern values when I press a key on my remote control: 11000101110101.

Q:What is the system I control and what will happen on it (key pressed on my remote control)?
A: To answer this question, you have to order the patterns in the blocks they belong to: 11 for the start block ,0 for the CONTROL block ,00101 for the SYSTEM block and finaly 110101 for the COMMAND block. If you calculate the decimal values of SYSTEM and COMMAND blocks , you will get 5 and 53. With the translation tables codes , you will easily deduce that I launch the play of my video tape on the video recorder by pressing on the PLAY key.

Moreover, I wish simulate my remote control with the PC to reccord a film .

Q:What are the SYSTEM and COMMAND values I have to choose to generate relevant electrical signal?
A:Easy for the SYSTEM value , it is the same as previously: 5 only the code value of COMMAND change and vault 55. To see the signal waveform generated by your remote control when you pres the key REC, enter this two values valeurs by clicking on the SYSTEM and COMMAND butons.

II - PRATICAL SIDE

1) Decoding a RC5 frame

Done ,but Scope pictures not ready yet.

2) Encoding a RC5 frame

Not done .

III- Programs

Not available for the moment.