Tag Archives: USB volume knob

A tinyAVR USB volume knob

A Maker by the name of Rupert has designed a tinyAVR-powered USB volume knob based on Adafruit’s popular Trinket (Atmel ATtiny85) platform.

“After purchasing a Trinket to experiment with and Adafruit having a great mentality for Open Source Hardware, I decided to modify my own ATtiny85 volume control PCB to make it compatible with the Trinket’s 5Volt firmware (flash_me_hv_5volt.hex)! (which is Arduino compatible),” Rupert explained in a recent blog post. “This gives access to direct programming without the need for a separate programmer from the Arduino IDE. Its also nice to support the hard work done at Adafruit by purchasing one of their Trinkets.”

As the HackADay crew notes, an awesome looking RGB LED ring powered by Adafruit’s Neopixel was ultimately added to the design, albeit at the expense of a “mute” control.

“The PCB Rupert fabbed is pretty well suited for being manufactured one-sided,” wrote HackADay’s Brian Benchoff. “If you’ve ever wanted an awesome volume knob for your computer, all the files are available from Rupert‘s blog here.”

In addition to creating the above-mentioned tinyAVR USB volume knob, Rupert is reportedly working to load Adafruit’s Trinket bootloader on Atmel’s ATtiny84, an MCU with a total of 8 analog pins.

As we’ve previously discussed on Bits & Pieces, Adafruit’s popular Trinket can best be described as a tiny microcontroller board built around Atmel’s versatile ATtiny85.

“We wanted to design a microcontroller board that was small enough to fit into any project – and low cost enough to use without hesitation,” Adafruit’s Limor Fried (aka LadyAda) explained.

“[It is] perfect for when you don’t want to give up your expensive dev-board and you aren’t willing to take apart the project you worked so hard to design.”

Fried describes the Attiny85 as a “fun processor,” because despite being so small, it boasts 8K of flash and 5 I/O pins – including analog inputs and PWM ‘analog’ outputs.

“We designed a USB bootloader so you can plug it into any computer and reprogram it over a USB port just like an Arduino,” Fried continued. “In fact we even made some simple modifications to the Arduino IDE so that it works like a mini-Arduino board. You can’t stack a big shield on it but for many small and simple projects the Trinket will be your go-to platform.”

There are currently two versions of the Trinket: 3V and 5V. According to LadyAda, both work the same but have different operating logic voltages.

“Use the 3V one to interface with sensors and devices that need 3V logic, or when you want to power it off of a LiPo battery. The 3V version should only run at 8 MHz. Use the 5V one for sensors and components that can use or require 5V logic, [as] the 5V can run at 8 MHz or at 16MHz by setting the software-set clock frequency,” she added.