LED SMD firefly built around an ATtiny85

A Maker by the name of Tyson has created an “electronic firefly” built around Atmel’s popular ATtiny85 microcontroller (MCU) and a custom PCB.

Additional project components include:

• (2) 12 pf 0805 capacitors
• (1) 100 kOhm 1206 resistor (for reset line)
• (1) 1 MOhm 1206 resistor (for LED discharge)
• (1) CR2032 battery holder (BC2032-E2 at Digi-Key)
• (1) CR2032 battery
• (1) Clear Orange 5mm LED (754-1271 at Digi-Key)
• (1) 32 kHz crystal (535-9166-1 at Digi-Key)
• (1) 8 to 12 oz Mason Jar
• 2-3 oz sand

Before kicking off, Tyson reviewed Karl Lunt’s asynchronous fireflies project, with the overall goal of simulating intermittent blinking in low-light conditions like a firefly.

“Using the existing project, I did need to modify a few things. First off, I was using an ATtiny85 instead of the ATtiny13a, as well as an external clock,” Tyson explained in a recent blog post.

“Luckily, the external clock only required a few fuses to be set as far as programming went and a couple load capacitors to allow it to be used with the MCU. The ATtiny85 required a few code changes because the output port for the LED and mux for ADC had to be changed among other registers.”

In terms of the PCB, Tyson used photo paper for the print and Eagle to create the necessary traces. He then soldered on the ATtiny85 and set the appropriate clock speed.

Interested in learning more about building LED fireflies with Atmel’s ATtiny85 MCU? You can check out HackADay’s coverage here, the project’s blog page here and the source/board schematics here.