With the new battery mount & buck converter box installed on Mary’s bike, I updated the running light circuitry to match the ones on my bike. The original wiring just supplied 6.3 V from the headlight circuit, but now the four wire ribbon cable from the electronics box carries 6.3 VDC from the buck converter and a 6 VDC signal going high when the DPC-18 display’s “headlight” output goes active. The latter goes into an optoisolator pulling down Pin 2, telling the running light to stay on continuously.
The optoisolator sits next to the Arduino Nano’s Reset button:
The black wire barely visible below the optoisolator jumpers Pin 3 to ground, telling the firmware that this is the front running light.
The black & white wires from the top of the optoisolator connect directly to the ribbon cable entering on the other side:
The gray wrap of clear silicone tape mummifies the wire-to-wire soldered connectors.
The firmware now pays attention to the jumper input, so I need only one source file for both front and rear lights:
if (digitalRead(PIN_POSITION) == HIGH) {
Blinks = String("i e "); // rear = occulting
Polarity = true;
}
else {
Blinks = String("n e "); // front = blinking
Polarity = false;
}
It just doesn’t get much easier than that!
The Arduino source code as a GitHub Gist:
The Smell of Molten Projects in the Morning 