This simple and  funny toy can kill 10 minutes of your time
if  you play yourself,  and hours, if you do it with friends. 

1. IR remote control for 'Battle Tank'.

  This IR (radio) control has one interesting feature. It independently controls three electric motors, unlike most others. For example, this is not possible if you use RX2/TX2. Therefore, it is interesting to know how they do it. Of course, everything can be done without opening the hood, but it will free us from additional fun of knowing that inside.
   Let's start with a simple one. Remote control allows you to move the toy forward and backward, and turn the turret left/right. In addition, the 'Fire' button, lights the LED on the barrel once per click.

   Inside you can see on the right. There is only a chip, covered with black compound, under the board. Timing runs from 6MHz crystal. I installed only a jumper (K1/K2) that allows me to switch between toys number 1 (gray color) and 2 (beige).
    The encoding of the main commands for toy number 2 (jumper in K2) is shown in the picture. Wide impulses (let's call them starting) are accompanied by short ones that carry simple data.

    If you skip the starting pulses, and count the subsequent ones, you get an encoding. For an example for "Turret, left turn" it will look like "2-6-1-1". To save space, the main commands in the following table.

     For what would it be some sort of system. The first digit carries information about which toy the command is passed to. The second is an addition to the first. Add the first to the second. The amount will be constant for each. The third and the remaining digits are the command code itself.

2. If you want to repeat this coding on the micro controller.

    In order to repeat this it is necessary to know the timing. The length of the pulses in milliseconds is shown in the picture. This is done using markers on "Tektronix" scope and should be very close to reality.

   The following shows how often the commands are repeated, if you hold the button down and the carrier for IR signal. The latter will depend on the type of IR receiver. The frequency can be 36-39, or 57 kHz (as for RC helicopters).

    More precise characteristics of the carrier frequency you can see here or if you click on the last picture.

3. And why all this?

    Just need a core to prototype of a self-monitoring robot that must turn the sensor system left and right, to look around before making a decision.

4. Conclusion.

    At the moment, you have all necessary data to repeat this encoding on TI MSP430 or Arduino. Do not forget that the IR signal requires a carrier (~36kHz), which is not so easy to get with internal timers. A bit of simple code can be found here. This is for set of RX2/TX2 working on RF, and in another language. But "Google Translate" works well and it will not be a problem.



June 17, 2017 JB & SKootS


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