You could do one pulse with 6 different widths, you could encode rows and columns as on and off times, you could do something wilder.
I think that having the number of pulses vary with the button is the least likely.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Have a device with a corded remote control. 3 conductors. Had to take it apart. Inside, the conductors are labeled +V, Gnd, Signal. The remote is a
6 button job. There's a 555 and a transistor nearby. Lots of resistors and caps.So? Any guesses what they send out? A square wave with the number of pulses to correspond with the button number? A single long pulse with the width in proportion to the button number?
How would you design it?
What's it controlling? If it's a servo motor, then the 555 is probably sending control pulses of around 50 Hz with pulse widths between 1-2 ms, to position the motor.
-- Terry Pinnell Hobbyist, West Sussex, UK
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Most simple form of remote, by changing the timing resistor the 555 gives a different frequency for different buttons pressed, or varying the control voltage pin (pin 5) which will change the trip point for the turn off (discharge phase) frequency would be the easiest to decode with either a micro or tone decoder (such as lm567)- I am amazed they require all three wires- I've done this trick with 2 wires, ground and a combined power/signal by superimposing the square wave frequency onto the power line. Another trick to lower the emc problems is to charge the cap on the 555 with a current source (maybe the tranny on the pcb) and then use the VC (pin5) to vary the frequency of the resulting triangular wave on pin 6 Smashing chip the 555 Regards Anthony
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