Eight-pin microcontrollers offer numerous peripheral features. However, the maximum number of I/O pins available is often limited to six, since two pins would be required for the chip's power supply.

As in a previous Design Idea (Reference 1), this design uses an LED as a transducer to measure the ambient-light level and to provide illumination. This Design Idea uses the same principle as its ...

Microcontroller port pins can typically be driven either high or low, or else be put into an "input" or high-impedance state. This circuit uses the three states to drive two separate LEDs with one ...

“Charlieplexing” as a method of multiplexing LED displays has recently attracted a lot of attention because it allows you, with N I/Olines, to control N×(N–1) LEDs (reference 1 through reference 5).