BLU-PI CYCLING COMPUTER

GPS Cycling Computer | Raspberry Pi + GPS + ATTiny Odometer | Node.JS

Overview	Intervals	Sys. Averages	Map	Menu

Setup	Cockpit	Prototype

Install & Running

Install dependencies:

$ npm i

Running:

$ node app

Start on background (under screen):

$ ./start_and_watch_for_cycle.sh

Install as service on Pi:

sudo cp blu-pi.service /etc/systemd/system/blu-pi.service
sudo systemctl enable blu-pi.service
sudo systemctl start blu-pi.service

Usage

• Rotating (the Rotary Encoder) provides input within the current screen
• Push button to trigger an action within screen
• Press Push button + rotate Encoder to change displays:
  • Overview: Session elapsed time, distance, current speed and cadence.
  • Averages: Display Speed/Cadence and CPU/Temperature/RAM (on different scales)
  • Intervals: Lap times, using GPS anchor or by distance
  • Map: Plot of GPS points
  • Off: Minimal display
  • IP: Display device IP(s)
  • Menu (see menu.js)
    • Dim display
    • New session
    • Reset wifi
    • Reset pi
    • Turn OFF

Web Display

Open http://[PI-IP-ADDRESS]:8080/ for a mirror of the display.

Use ASD keys to mimic Rotary Encoder. Long press A and D to switch screens.

Hardware

Build & Wiring

• 3xGPIOs for input + 2 GNDs
  • rotary.pinA -> pi.gpio16
  • rotary.pinB -> pi.gpio26
  • rotary.push -> pi.gpio21
• using i2c (+ VI + GND)
  • oled display
    • + reset pin on pi.gpio4
  • attiny odometer (see more details)
    • attiny.vi -> 10k resistor -> attiny.gpio3
    • attiny.ground -> reed switch -> attiny.gpio3
  • lsm303 (currently not in use - can be used to normalize GPS) (adafruit)

I2C Device Addresses:

• 0x3D: OLED
• 0x13: ATTiny Odometer
• 0x1E: LSM303 Magnetometer
• 0x19: LSM303 Accelerometer

Parts

• pi a+ (or zero)
• wifi dongle (or zero+w)
• adafruit's gps hat (adafruit)
  • or gps module + permaboard for wiring everything (5cm~ x 8cm~)
• oled 128x64 (configured with i2c) (adafruit)
• input: rotary encoder + push button (adafruit)
• cadence:
  • lblue(tooth) cadence or speed meter
• odometer:
  • attiny 85
  • reed switch
  • 10k resistor
• RJ45 (jack + connector) to connect the Rotary Encoder + Odometer pins to the Pi and ATTiny

CREDITS

Libraries

(See package.json for all depedencies)

Adafruit GFX port to JavaScript (display/adafruit-gfx)

https://communities.intel.com/message/237095#237095

TinyWire - ATTiny I2C library:

https://github.com/rambo/TinyWire/tree/master

Distance (using GPS):

https://github.com/Maciek416/gps-distance

GPX parsing:

https://www.npmjs.com/package/gpx-parse

BLE Sensor reading (sources):

https://github.com/amcolash/BikeVR/blob/master/public/js/bluetooth.js https://github.com/amcolash/oled-bike-computer/blob/master/bluetooth.js https://github.com/kdevware-andre/kdevware-andre.github.io/blob/master/bluetooth.js

References

ATTiny Flashing:

https://www.instructables.com/id/Programming-the-ATtiny85-from-Raspberry-Pi/

Map lat/long to pixel:

http://stackoverflow.com/questions/8898120/conversion-of-lat-lng-coordinates-to-pixels-on-a-given-map-with-javascript

Kalman filter:

https://wouterbulten.nl/blog/tech/lightweight-javascript-library-for-noise-filtering/ https://hackaday.com/2019/05/14/the-kalman-filter-exposed/