Select Page

So two weeks ago I showed the sound gizmo I sent my friend. While it’s a neat sound maker, it’s decidedly weak in the user interface department.

There are three items I want to add to make it more musician friendly, namely:

  • A display to show parameters and options
  • Knobs and buttons to adjust parameters
  • A way to input musical notes

Over the next few weeks I’ll put all that together and add new posts when I have something new to show.

Anyway, I’d thought that by now I’d have the completed display up and running but since I was on the West coast for work training, I only got around to wiring up the first part of the display, namely a 74HC595 shift register.

The ‘595 is used to keep as many pins free on my processor as possible. This method only requires 3 pins instead of 6 to drive the display at the expense of the speed I can change the characters on the display. There are countless articles on the web that talk about this but the code I’m using was written by me. Speaking of the display, I’ll eventually wire-up a Hitachi HD44780-compatible LCD but this week, I’ll just showing the data pins on LEDs so I can make sure my code is working properly.

Here’s a rough layout of how I have everything hooked up:

So without further ado, here’s a video of the gizmo flashing the LEDs in patterns so I could be sure how I’m wired up and which direction bits are getting shifted in but it isn’t making any sound this week so don’t turn up your speakers, because this week it’s silent: