Tag Archives: Arduino

ATtiny Programming Jig – Part 1

Lately I have been making a few projects with the ATtiny84/85 micro controllers. The pumpkin light controller I presented a few months ago, as well as a brushless motor controller I have been playing with (amongst others) have been built with these controllers. I use the Arduino IDE to write and compile the code and an Arduino programmed with the ArduinoISP sketch to write the code into the chips.

At first, I wired up a small breadboard, which worked fine until I needed the breadboard to test something else. Arrrgh. Need to make it more permanent. Rather than make one board for each of the controller types I have, I built it for all three – ATtiny84/85/861. So far, I have tested it with the 84 and 85 with perfect results.Photo on 1-15-14 at 10.15 PM

I always like to put a cheat sheet on the underside of my boards. Not only does that help in remembering which pin connects where, but it also serves as an insulator. I cover both sides of the paper in clear packing tape (poor man’s lamination), punch a few screw holes and attach it with some risers and screws. Keeps the solder side out of the inevitable clipped wire strands and soda-pop condensate puddles.

Photo on 1-15-14 at 10.16 PM #2

The jig includes the Arduino reset override capacitor and LED indicators referenced in the ArduinoISP code. The lights sure look nice when blinking, but about the only thing they really show is whether code is being written to the ATtiny or not.

This jig has worked well over the past few months, but is also wearing out its welcome. I am currently working on an Arduino shield version, which will make it much easier to disconnect and reconnect the jig, without taking my glasses off to see if I connected the jumper to the right hole or not. More info to follow.

Meanwhile, here is a draft schematic of the board, for those who are interested: attiny programmer.sch

 

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Haloween Pumpkin Light Project

Every year we make a pumpkin to decorate the front porch for Halloween. My daughter, the artist in the family, traces the design on the pumpkin, I cut it out, we add a generic pumpkin light and wala! a pumpkin is ready.

This year I thought I would do something different. I had a few strips of red/blue/white 12v LEDs my Dad once gave me (and is impatiently waiting for me to do something with them!), and I decided to make a mood light based red/blue LED driver with the white LEDs flashing to create a sparking effect.

Rather than use a full Arduino for this project, I decided to try my hand at using the smaller format ATtiny84 on a custom board. I had recently bought some for tinkering and this seemed like the perfect first project. Much easier than I thought. Installed the AVRisp software on my Ruggeduino, connected the leads as required and added a few LEDs for testing. Works!

Ruggeduino as AVRisp

Ruggeduino as AVRisp

Why Ruggeduino, you ask? EZ. I have already blown up used up all of my ATmega328 chips on other projects and I have yet to find a way to destroy the Ruggeduino. Wish I could say that about my UNO you see in the background of the pic above… but that is for another story.

With the ATtiny programming issues sorted out, time to figure out how to drive the 12v LED strips from the ATtiny. Despite using high gain A63 Darlington NPN transistors, I was not able to get the LEDs to full brightness with a single transistor. I found that if I use a 2n2222 to pull the base to ground, I could get the desired light output.

Prototyping the Pumpkin LED driver

Prototyping the Pumpkin LED driver

The software is a mashup of a moodlight sketch and a firelight sketch I had laying around. I added some potentiometer control to limit the brightness of the flashing white light. This would make the board more universal for other seasons. Once I was satisfied the design works, I put it all together on a piece of Radio Shack protoboard I had laying about. I wrapped short LED strips around a cardboard tube and dangled it from the top of the pumpkin.

LED controller board ready for use

LED controller board ready for use

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A more visual representation of the project can be seen in a short video I uploaded to YouTube earlier today.

Oh… do you think any of the kids noticed the cool pumpkin by the door? sigh… damn candy…

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Happy Halloween!