my recent reads..

Atomic Accidents: A History of Nuclear Meltdowns and Disasters; From the Ozark Mountains to Fukushima
Power Sources and Supplies: World Class Designs
Red Storm Rising
Locked On
Analog Circuits Cookbook
The Teeth Of The Tiger
Sharpe's Gold
Without Remorse
Practical Oscillator Handbook
Red Rabbit

Sunday, March 20, 2016

LittleArduinoProjects#196 Driving a 7-segment display with CD4026 Counter

Here's yet another way to drive a 7-segment single-digit display unit - using a CD4026.

The CD4026 is a 5-stage Johnson decade counter with decoded 7-segment display outputs and display enable. With RESET and CLOCK INHIBIT low, and DISPLAY ENABLE IN high, the 7-segment display outputs progress through the 0-9 sequence on the rising edge of the CLOCK pulse.

It's an interesting alternative to a shift register for driving a 7-segment LED (as in the ShiftDrive project). While a latched shift register provides random addressing and clean transitions to any digit, it requires the 7-segment display outputs to be decoded externally (like in code). On the other hand, the CD4026 takes care of the decoding, and external circuits just need to send a counter pulse.

As always, all notes, schematics and code are in the Little Arduino Projects repo on GitHub.

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