Hackable LED Christmas Card

Overview

This hackable version of holiday card is based on an ATtiny13A and a few LEDs that play a short light show in the tree upon pushing the button.

Explanation

From the small Atmel ATtiny13A microcontroller, one pin for PWM blinks the lights while most of the other pins are used for programming and power which can operate similarly with the effects using a 555 timer of discrete components. To hold the reset pin high, the ATtiny13A needs a 10K pull-up resistor. The chip can be reset with a mini tactile switch by connecting the reset pin to ground and it can be decoupled from the power supply using a capacitor.

Through a 6-pin in system programming (ISP) connection, the ATtiny microcontrollers can be programmed where the ISP is oriented towards the back of the card. To avoid soldering a pin header on the board, a programming probe was created. Since the ATtiny can operate over a range of voltages down to 1.8V, a 3V 20mm lithium coin cell is used to supply the power and placed at the back of the PCB. The battery holder should work with a 2025 or 2032 coin cells.