BCNK-Blinker

The author's first professionally made PCB, from 2008. An ATTINY13 blinks five LEDs to fake police lights, ambulances and broken fluorescent tubes on the Modulegroep BCN model railroad.

What's on the board

• An ATTINY13.
• Five LEDs.
• Five 180 ohm resistors.
• An AVR ISP header for programming.
• A 0.1uF decoupling cap.
• 5V input.

The blink pattern

The ATTINY13 runs a loop that toggles its output pins in a timed sequence. Each LED has its own pin, so the firmware shapes the flash pattern: alternating for a patrol car, fast for an ambulance, erratic for a dead fluorescent. 180 ohm per LED keeps the current sane on 5V.