74LS595 Shift Register Tutorial

74LS595 Shift Out Register Tutorial

Since I’m new to electronics I thought I would document some of my successful experiments. Both so others can learn from my progress and so I can have a reference to revisit in the future in case I run into problems. I have an idea for an Arduino project that will require more I/O than the UNO is capable of. I learned that shift registers are a great way to expand the number of Inputs or Outputs you can handle, up to eight at a time. The way they work is pretty straight forward. In the case of shift-out registers, you simply push a pattern of HIGHs or LOWSs onto a stack internally on the IC. When you make the latch-pin HIGH, everything you pushed in serially will be converted to paralell outputs. That is, 8 of the pins on the shift register will go HIGH or LOW depending on the serial pattern you input. Shift-In registers work similarly in reverse, allowing you to read the state of 8 pins on the IC all at once, then stream their values in one at a time serially to the Arduino. The advantage of this is that you can have up to 8 inputs or outputs, while only using 3 pins on the Arduino. But what’s even more impressive is that you can daisy chain these ICs back to back. If you use 2 74LS595 shift-registerts back to back, you can have SIXTEEN outputs, while still only using three pins! In fact, you could use four 74LS595s in a row and have 32 outputs and still only 3 pins on the Arduino. Handy!

While I thought this would be an easy build, I ran into lots of problems, mostly having to do with floating values. After figuring out that I needed some pull-down registers I got everything working. Check the video below for the build:

July 23, 2014 at 10:17 pm | Video

 

Add Comment

* Required information
(never displayed)
 
Bold Italic Underline Strike Superscript Subscript Code PHP Quote Line Bullet Numeric Link Email Image Video
 
Smile Sad Huh Laugh Mad Tongue Crying Grin Wink Scared Cool Sleep Blush Unsure Shocked
 
1000
 
Notify me of new comments via email.
 
 
Powered by Commentics

Comments

No comments yet.
© Greg Miller, 2009-2019
2fc29791367c6a4ba13727b560c2f2bd7c5945e536a239782d