Wiegand Clock/Data Converter AVR

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Converts wikipedia:Wiegand encoding to clock/data format. This is version 1 of the converter. Version 2 (Wiegand Clock/Data Converter PIC) used a PIC processor, and supports both Wiegand to clock/data and clock/data to Wiegand conversion.

As DATA0 or DATA1 goes low, the data line is driven accordingly, followed by a pulsing the clock line low for 140 microseconds. Should both lines be low, then the transitions are ignored.

In both cases, if the inputs make transitions while the 100us timer is active, the transitions are ignored.

The code is completely interrupt driven, and the processor is asleep when the 140us timer is not running. The quiescent current is extremely low, although I don't recall the measured value.

An LED is lit when the 140us timer is active. This gives a good indication of the traffic present.

Schematics

PCB

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Source Code