Using 74HC595 and CD4017 to expand IO of MCU for driving a scrolling dot matrix display

Using 74HC595 and CD4017 to expand IO of MCU for driving a scrolling dot matrix display

I found this very well written blog post on the web on how to use your microcontroller with limited I/O pins to drive large dot matrix led displays. The article explains how to use 74HC595 shift registers to scan multiple dot matrix display modules’s columns and a CD4017 decoded counter to scan the rows. All together you will need 3 I/O pins for the shift register and only 2 I/O pin to drive the decoded counter.

Here is the link: http://embedded-lab.com/blog/?p=2661

I have used 74HC595, CD4017, ULN2003 chips to drive dot matrix displays already using arduino, but that was static/non-scrolling. This blog post gave me better understanding on how to do the scrolling.

One thought on “Using 74HC595 and CD4017 to expand IO of MCU for driving a scrolling dot matrix display

  1. tecdroid

    Hi,
    why didn’t you just use another 74HC595 instead of CD4017? you still need to drive the rows with an ULN but you’d need just 3 pins which means, you could drive the whole thing with a SW USART on a ATtiny25 or similiar.
    I can’t imagine that this slows things too much up to make it viewable..

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