My degree is actually in electronics so there are occasions where I go back to my roots and make little electronics projects. One of my favorite microcontrollers is the Teensy. This pic shows the midi controller I'm building to control Reaper from behind my drum kit. Next steps for this project:
- Add infrared sensor so it can be controlled without using wires.
- Take it off the breadboard and package it up so it looks nice.
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This is a 32 output expansion board made up of four daisy chained 74HC595 8-bit shift register chips. It can be controlled using SPI or with discrete outputs from your arduino or other microcontroller. The default configuration is that the output enable lines of the four chips are connected to ground, but, by cutting the traces between the OE pads, the pins could be controlled externally.
I made this pin for my daughter, who happened to be the president of her chapter at the time of this article. It was fun to make and I learned a couple new things.
- How to make irregular PCB board shapes.
- It's my first surface mount PCB of any significant size.
I used an Atmel ATTiny85 microprocessor with 33 ws2812B led's. There are 2 switches on the front, one to reset the microprocessor and one to force it to change the light pattern. On the back are 2 JST-PH connectors, one 6-pin for the SPI programming interface and one 2-pin for the battery connection. I use a small Li-Po battery which is small enough to be attached to the back of the pin using velcro.
If you've ever used any of the WS2812B led's then you know how bright these things can be. When all 33 led's are lit, this thing is BRIGHT! You could probably see it from space. It was designed to be a pin so there's also a large pad on the back to which a run of the mill pin back is soldered.
Here is the pin when lit:
This board uses a 555 timer configured as a one-shot to provide a clean digital pulse to a microcontroller. You can connect a piezo disc to the two TRG pins, vcc, and ground and the output pin will give you a 20msec pulse when the piezo is struck. There's an npn transistor on the input so it can be triggered on a positive pulse. This circuit would allow you to connect a piezo to your arduino or other 5V microcontroller project.
Buy this board on OSHPARK
I needed an Atmega328 board with wireless capabilities for a recent project so I decided to put one together. This board uses an SMD version of the Atmega328p-pu which is called the Atmega328au. The au version is in a 32 pin tqfp package which is fairly easy for the hobbyist to handle. It has a JST-PH connector for powering with a li-po battery, a 3.3 volt low dropout regulator to power the radio, and runs at 16MHz. Standard spacing holes allow it to be plugged into a breadboard if pins are soldered to it. For my project I needed a voltage divider connected to each of the ADC pins so there are spots for 8 smd 0805 resistors that have one side grounded.