Principles of infrared communication & Infrared Remote Control

Infrared is an invisible light to the naked eye, with a wavelength of approximately 950nm. Infrared light however can be detected with one of the modern digital cameras that have night vision functionality.

Digital Infrared signals are create by transmitting short and long pulses of infrared light. The code is similar to the principals of Morse code using long and short pulses.  A long pulse of 1.2ms is represented a digital 1 and a short pulse of 0.6ms is represented as a logic 0.  There is a 0.6ms pause between each pulse.

The SIRC infrared signal is made up of a 12-bit packet, which is split into a 7-byte button code and a 5-byte device code. The button code represents the actual button pressed on the remote control.  There is a 2.4ms ‘start bit’ between each packet, which is used to synchronize the sensors.

The device code determines which remote control device is being address; such as video, television, CD, Amplifier, SAT, etc.

Infrared Remote Control within the IR Control Freak Modules

IR-Control Freak  is equipped with an onboard Infrared remote controlled receiver and transmitter, for control of robots and electronic projects using a standard TV remote control. The protocol used with IR Control Freak is the Sony format known as SIRC.

A remote control feature enables inter-robot communication and Robot Gaming such as tag, zapping, Robot team communication, etc.

Buy using coded IR messages; you can transmit signals to other robots. For example, it is possible to determine whether your robot opponent is a friend or foe. You could also configure a unique ID for each robot and robot team, allowing your robot to communicate between team members and sending a 'tag' or ‘zap’ code to the other opponent team. For example, ten ‘zaps’ to the centre sensor could mean, ‘your dead’!