SV650overlay

Suzuki SV650AK7 motorcycle gear indicator and diagnostic data monitor using an ESP32, an Android app and Bluetooth connectivity

Features

• ESP32 reads diagnostic sensor data from bike ECU via K-Line (SDS protocol) and sends it via Bluetooth
• Android smartphone app receives, processes, displays and optionally records the data in csv format
  • Background service handles Bluetooth connection, receives data and processes gear information for overlay
  • Movable overlay displays current gear and connection status in 7-segment display look, on top of all other apps (e.g. navigation, music player)
  • App screens/activities to discover Bluetooth devices, control the background service, display and record data
  Screenshots (click to expand)

  

Motivation

The Suzuki SV650 has no built-in gear indicator. There are off-the-shelf solutions to add one, like the Multibot or external gear position indicators, but they seemed not really appealing to me.
So I looked further and found https://github.com/RaysceneNS/SV-650-GearPositionIndicator - an attempt to read the gear position sensor analog voltage directly with an ATtiny microcontroller. I built, but never installed it because I feared it would affect the signal for the ECU.
Later on I discovered https://github.com/o5i/Datalogger - an Arduino based datalogger using the diagnostic interface of the bike (K-Line aka ISO 9141 with Suzuki specific KWP2000 aka ISO 14230 protocol implementation, called SDS). I took an ESP32, ported and adapted the code and tried it out.
It ran so flawlessly that I thought it would be cool to extend this with an app displaying the data on my smartphone.
So here it is now - not only showing the gear, but also some additional diagnostic data. Some conversions are missing or inaccurate, but the main objective is achieved.

Hardware

• ESP32-DevKitC (WROOM32)
• DSN-MINI-360 DC-DC buck converter board (DevKit's LDO gets very hot when running with bike's voltage and capacitors are designed for max. 10 volts, as I found out after some cutouts ... so this steps voltage down to 5 volts for the ESP32 first)
• ST L9637D Monolithic bus driver with ISO 9141 interface
  • Tx/Rx pins are connected to ESP32 UART2 (hardware serial, GPIO 16/17, Pin 25/27)
• Diode 1N4007 (input)
• Resistor 510 Ohm (K-Line pull-up)
• For schematics, refer to https://github.com/iwanders/OBD9141 and https://github.com/aster94/Keyword-Protocol-2000 (works fine for me with one diode and without capacitors)
• 6-pin MT .090 Sealed connector (diagnostic interface of the bike)
  • Diagostic connector pinout (base color/line color):
    • Black/white: GND
    • Orange/green: switched +12V
    • White/red: dealer mode (when connected to GND)
    • Gray/red: K-Line

Software and Frameworks

• ESP32 firmware (ESP-IDF)
  • https://docs.espressif.com/projects/esp-idf/en/stable/esp32/get-started/
• Android app (Android Studio and SDK tools)
  • https://developer.android.com/studio/

Additional Information

• Tested on Android 9 and 10
• Designed for Sony Xperia XZ2 Compact screen (resolution 1080x2160 px FHD+)
• Recorded log files are stored in internal storage (/storage/emulated/0/Android/data/de.bananajoh.sv650overlay/files/)
• K-Line post frame delay (T_04) was increased to 200 ms (initially 50 ms), so the resulting refresh rate is about 3-4 Hz instead of 6-7 Hz - reducing load (aka thermal cutouts) and log file size

References

• SDS protocol thread on ECU hacking forum: https://ecuhacking.activeboard.com/t22573776/sds-protocol/
• 7-segment display images: http://avtanski.net/projects/lcd/
• Similar project: https://github.com/synfinatic/sv650sds
• Similar project for Kawasaki: https://github.com/HerrRiebmann/KDS2Bluetooth