I was posting to the thread on the embedded clock in a Manchester encoded bit stream and realized that the clock is not truely embedded in the data stream. I say this because you still have to know the clock rate in order for it to work. The decoder has to lock out the edge detection for the time between bits to prevent detecting false bits. You have to know the data rate in order to time this lock out period. Of course the timing is much less critical than a typical clock, even an RC clock. But none the less you have to have a clock of a given frequency.
Are there any methods of transmitting data and clock on a single wire that do not rely on the decoder having knowlege of the clock rate. This is not entirely academic. I have an interface I am working on where I need to multiplex multiple signals over a single pin. One is a serial bus and the others are discrete pins which require very accurate timing. Idealy the decoder would not have a clock, but rather the data would be self clocking. I would like to use a very low power CPLD that could be powered by either the signal or at least only require a few mA of current from an LDO on the battery connection.
Is self clocking on a single pin possible? I am thinking that the extra info has to be presented in some manner that requires either a timing or amplitude measurement.