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IR remote control 2

IR remote control 2

IR remote control v2 is a modification of RobotSM and RobotChallenge offical sumo robot remote control. The original device was designed by Erik Sternå from CRF. As similar infrared transmission devices had been used on Robotex competitions as football goal beacons, it made sense to design and use one IR transmitter device for football and sumo competitions.


The changes compared to the original RC schematics are:

  • Adjustable IR LED intensity. Needed when using as beacon.
  • Added step-up DC/DC converter to get fixed voltage. Fixed voltage can guarantee fixed IR intensity and makes it possible to use AA rechargable batteries (which have lower voltage than disposable batteries). Downside of DC/DC converter is that the output current consumption must always be at least 1 mA in order to maintain the correct output voltage. This means that there can't be too much power saving.
  • Added IR receiver. Useful for testing other beacon and to synchronize with other beacon signal.


Original sumo RC5 SW should be mostly compatible with new schematics except the battery voltage measuring. Sumo SW has not (yet) been modified.

Robotex soccer goal beacon SW is written in AVR studio with Homelab library. It can be downloaded here:

Usage instructions

Board overview

Depending on the SW, the remote control can have different functionality.

Robotex soccer goal beacon

Remote control works with 2 x AA disposable or rechargeable batteries. When powering from power supply, keep voltage between 1-3V. If supply voltage drops to 2.1 V (it means 1050 mV per battery) the red LED will start flashing slowly. If voltage further drops to 1.7 V (850 mV per battery) the red LED will start flashing rapidly. As the board has step-up DC/DC converter it will work normally with total voltage down to ~0.7 V. The remote control cannot save batteries from fully emptying therefore it is up to user to avoid it.

With beacon SW, the channel selection switches allow to select transmitted channel 1, 2, 3 or 4. The first channel switch in up position is used as a transmittable channel. It means that if for example switches 2 and 3 are up, then channel 2 is selected. Channel 5 switch is unused. If some channel is selected then corresponding green LED (1-4) will light up constantly and two leftmost IR LED's with -15° and +15° placement will transmit PWM modulated channel signal (more about signal in Robotex football rules).

While pushing start button, remote control stops transmitting and will receive IR PWM signals from other beacon and shows the received channel number by the 1-4 LED's. If no signal is received then no LED is lighted. This feature is useful to verify the other beacon operation and it can also be used for adjusting the other beacon signal transmission strength with intensity potentiometer.

Stop button does nearly the same as start button, but it has a low-pass filter for signals. It means that signal is considered correct only when four consequitive channel signals are received. This could be useful in beacon intensity adjustment to filter out invalid signals which could be the cause of weak signal, long distance or reflections.

Prog button will start beacon synchronisation with another beacon. Syncronisation means that beacon will try to shift its transmission time between other beacon signals so there will not be any interference. Synchronisation is a one-time process and it should be done every time some beacon is turned on. It doesn't matter if one or another beacon is synchronised. It is worth to know that beacon timings can shift slowly over time and sycnhronisation looses its effect, so it should be repeated once a day or so. If there is no other beacon to synchronise with, then only way to return to normal transmission mode after starting synchronisation is to remove the batteries and reset the SW.


:!: This remote control IR LED's are not powerful enough to control 3kg sumo robots, especially when they have miniature IR receiver. Should change LED's or put them in parallel not series.


projektid/arendusprojektid/ir_remote_2.txt · Viimati muutnud: 2016/09/04 02:04 persoon