This page will take a while to finish, as the IR communication for Cybot takes a fair few issues to complete, issues 24 & 25 provide the first two parts, the infrared transmitter and receiver boards for Cybot's Dome and the Remote control Handset.

These first two circuits are extremely simple, and almost identical - the only difference being the pin connections to the plug, assuming the colour codes on the wires are used correctly they are wired the opposite way around. The circuits both use a single IR diode for a transmitter, there's no series current limiting resistor on either board, so presumably that will be mounted on the boards they connect to. The receivers look to be fairly standard IR receiver I/C's, although they are physically smaller than the usual type - these usually require a pull-up resistor on the output pin, and decoupling components on the +ve supply, again presumably they will be mounted on the boards they connect to. These IR receivers are very simple to use, you supply them with a decoupled 5V supply, and it outputs a demodulated signal at the output pin. IR communications modulate the IR light at around 38-40KHz, these I/C's detect and amplify the IR light signal, provide automatic gain control (AGC), detect the 38-40KHz modulation, and pull the output low while it's being received. You generally have to implement some kind of special coding technique, as RR state that there will be 16 possible channels (which uses 4 bits), and presumably they will send an 8 bit data byte, making a 12 bit word - not counting any possible start or stop bits. Stop bits are not usually used for IR, but start bits are pretty well essential. As soon as we get something transmitting I'll analyse the coding system used and post the details.

As usual I'll be adding the extra board details as I receive them, in the meantime if you want to know more about IR communications I have details of  how to make your own in my PIC Tutorial Series.

Cybot graphics used by kind permission of Eaglemoss
Last Updated 18/02/02 You can reach me by email at: nigelg@lpilsley.co.uk