multiplexing power meter
You can use a multiplexing approach, all the digit share the same data bus, every digit is drived by a single transistor each one which is connected to a single microcontroller input pin. Logic is simple, put the data for the digit 0 on the bus and switch on the digit 0, then after some time switch off this digit, put the data for the digit 1 and switch on the digit 1 and so on... just take care about flikering by using a suitable refresh rate, usually the switch on should be taken equal to 5 ms for every digit.
Bye
Pow