It’s been a while since my last update. I’ve been bouncing around between projects. The LED Shifter board, the subject of my most previous posts, works well and is acceptably bright. A  couple of the channels still trigger together, which needs to be investigated. While I’m troubleshooting that project, I’ll be posting a little about another: an analog input board.

I picked up several seven-segment displays a while ago; long enough ago that they have a cozy spot in my parts bins. Each module has two digits. I’ve been trying to incorporate them into something lately, and I decided to see what/how many I could fit onto a board:

I’ve also been trying out several different sensors lately (light sensors, microphones, etc.). I don’t really have a quick, easy way to measure their output without hooking them up on the breadboard and checking with my handheld meter, which can get pretty cumbersome depending on the situation. Being able to read, analyze, and log signals would be really helpful.

So a project framework and goal emerged. I have numerical displays and a need to display sensor values. From there, I started adding parts and connections in a “design-as-you-go” fashion. I felt very driven once I started this project and put a lot of work into it over the weekend. (I like to closely consider my puzzle pieces before setting them all down in a rush of activity.)

Here are some images of it in partial assembly:

I had a little trouble deciding which microcontroller to use. The ATtiny261 is small but still has 8 analog inputs; I had initially planned to drive the display with one. However, in the end the ATmega328P won out. It has more pins in total, which makes it easier to drive the display and still have plenty of input pins. Additionally, the ATmega has a built-in Serial interface that I hope to use to send commands/sensor data to a desktop computer.

I hooked it up with a test program as soon as I had completed enough to do so. Initial tests were done before the programming connector was finished, so I programmed the chip on another board (an Arduino) and transferred it to my board for the first few test runs. Here’s a shot of the board taken before the Atmega chip was installed:

Further tests went well, and the project has became more centered around the programming of the software than the hardware. I posted my first YouTube speaking role in the form of a video displaying a test version of the board:

Future posts will include how the display is driven and how the analog input section reads the values.