YouTube Uploaded by beat707videos on Jul 21, 2011
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https://github.com/Beat707/Beat707-BigTimeThis turns an ATtiny85/45 + 7-Segment 4-Digit Clock LED into a Beat + Measure display that connects to the Beat707 unit using only 4 wires. (TWI / I2C - SDA, SCL, Ground and 5V+)
Hardware used: ATtiny85 (using its internal Oscillator) - CD4067 Multiplexer - C595 Shift Register (serial input - 8 x parallel output) - 82 ohm resistor - 4 digits 7 segments LED clock display - ISP programmer (Arduino as an ISP device or USBtinyISP)
The great thing about this is that it doesn't hog on any of the free pins, it uses the shared I2C/TWI interface, which uses 4 wires and can have multiple devices sharing the same interface."