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Step 3Backplane & power source
The backplane provides power and a common I2C bus to both boards. Each board has 8 RGB LEDs and an ATmega168 mcu running with its internal oscillator at 8MHz. The latter requires synchronization between the boards and/or recalibration of the oscillators. This issue will show up in the code section again.
The schematic for the 5V boost converter was taken from the Maxim MAX756's datasheet without any modification. You can use any other chip you find suitable that can provide about 200mA at 5V. Just make sure the external part count is low. Typically you'll need at least 2 electrolytic capacitors, a Schottky diode and an inductor. The reference design in the datasheet has all the numbers.
I used high quality FR4 (fiber glass) boards for this job. The cheaper rosin based boards may work as well, but they break too easily. I don't want the boards to disintegrate on a bumpy ride.
If you already own a 'MintyBoost', you can use that as well if you can make it fit on your bike.
The schematic for the 5V boost converter was taken from the Maxim MAX756's datasheet without any modification. You can use any other chip you find suitable that can provide about 200mA at 5V. Just make sure the external part count is low. Typically you'll need at least 2 electrolytic capacitors, a Schottky diode and an inductor. The reference design in the datasheet has all the numbers.
I used high quality FR4 (fiber glass) boards for this job. The cheaper rosin based boards may work as well, but they break too easily. I don't want the boards to disintegrate on a bumpy ride.
If you already own a 'MintyBoost', you can use that as well if you can make it fit on your bike.
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