Rusty Wheels

Persistence of Vision bike wheel LEDS, using a Raspberry Pi Zero, Rust and 46 RGB LEDs.

Software

This repo, on top of Raspberry Pi OS.

Build with cargo.

Turn on spi in /boot/config.txt:

dtparam=spi=on

This should make these device files exist:

/dev/spidev0.0  /dev/spidev0.1

Configure the default mode of the magnet GPIO pin, in /boot/config.txt:

gpio=27=ip,pu

Configure the power off button on GPIO3, in /boot/config.txt:

dtoverlay=gpio-shutdown

Download this font gttps://gitlab.freedesktop.org/xorg/font/misc-misc/-/blob/master/5x7.bdf and save it as font.bdf in the working directory where the code runs.

Each time before running

Run this to make GPIO27 be an input with pullup: this is for the magnet sensor.

raspi-gpio set 27 ip pu

Hardware

• Raspberry Pi Zero
• 46 DotStar RGB LEDs, cut into two strips, one for each side of the wheel
• Hall effect magnetic sensor: Hobbytronics A1120EUA-T Hall Effect Switch
• Magnet
• Level shifter: v1 = SparkFun BOB-12009; v2, I'm hacking around with PCA9306 https://www.sparkfun.com/products/15439; v3 no level shifter
• Perma-proto board
• Screw terminals x 7
• Buttons x 3

GPIO connections:

• Hall effect sensor: GPIO27
• DotStar LEDs (SPI) (via level shifter in v1 and v2) MOSI and CLK
• Buttons: Smart power button: between SCL (aka GPIO3) and 0v. Other two buttons to GPIO12, GPIO13

Screw terminals:

• 3 for hall effect sensor
• 4 for dotstar LEDs
• 3 for external buttons (v3 only - unused so far)