Bike Odometer

A modular bke odometer that will get and display the speed and distance of the bike. It will also have the ability to control other devices such as a head-light/brake-light.

Bike Odometer is primarily a software base, but also providing a default hardware. Each official hardware will be stored on a separate branch.

Hardware Requirements

Rotary Encoder

To get the speed of the bike, a rotary encoder type sensor will be used. The sensor should connect to one of the interrupt pins.

In my case, a magnet and a reed switch is used as the rotary encoder.

Normally, the odometer is in sleep mode. When the wheels start turning, the odometer will wake up (because of the interrupt). If the bike has stopped for a prolonged amount of time, the odometer will go to sleep, waiting for the wheels to turn again.

USB Interface

Some settings for the odometer can only be changed through serial, so a USB Interface will be required.

User Input

The input used will be push buttons. I would recommend 3, though there is nothing that says you can't have more or less. The only requirement for buttons is that they all connect to the same PCINT port. There will be several functions that the buttons can do:

• Unit: Change display unit (SI, Imperial)
• Display: Change the main display mode (Speed, Trip Distance, Total Distance)
• Reset: Reset the trip—Total Distance should not ever be reset
• Lights: Toggle the headlights

^Bolded Items are recommended button configurations

These buttons change settings, so if a button isn't mapped, you can still change it's setting.

Display

A display that can output at least numbers is required—This is an odometer after all. Aside from this requirement, the display can be anything you want. A large amount of freedom is given to the display: a function pointer should be provided for updating the display (it will get called only when data has changed). The main loop is reserved for the display so that it can have as much control as needed.

Lights

Lights are optional, but having support for them is always good. If lights will be supported, they should be placed on pwm available pins, even if the lights aren't planned to be analog.

Diagram

TODO

Serial Interface

All settings will be modifiable through the serial interface. To make it easier to reconfigure, a terminal application will be developed to communicate with the odometer for you, but until then you will have to enter the commands directly to the odometer by hand.

There are several commands that you can use to interact with the odometer:

Description	Command	Return
Read Setting	read [reg]	[value]
Read Setting bits	rbits [reg] [bit] [size]	[value]
Write Setting	write [reg] [value]
Write Setting bits	wbits [reg] [bit] [size] [value]
Save Settings to EEPROM	save
Reset Settings to default	reset
Reload Settings from EEPROM	reload
Reboot System	restart

The register of a setting is it's location in EEPROM.

Settings

Rotary Encoder Settings

1. Wheel-Diameter (mm)
2. Wheel-Step-Conversion (Conversion from steps to rotations)
3. Wheel-Unit-Conversion (Conversion from meter to unit)
4. Display-Unit (up to 4 character unit name)

Sleep Settings

5. Sleep-Time

Button Settings

The button settings are stored in a single register, each button is 3 bits long, and so up to 9 buttons are supported:

6. Button-Register
   • 0-2: Button-0
   • 3-5: Button-1
   • 6-8: Button-2
   • 9-11: Button-3
   • ...
   • 27-29: Button-9

Button Action

Bits 0-1

0. unit
1. display
2. reset
3. lights

Bit 2

0. Increase
1. Decrease

Light Settings

There are 4 settings for the two lights each setting having for registers:

• Head-Lights-On 7. On-Brightness 8. On-Time 9. Off-Brightness 10. Off-Time
• Head-Lights-Off 11. On-Brightness 12. On-Time 13. Off-Brightness 14. Off-Time
• Head-Accelerating 15. On-Brightness 16. On-Time 17. Off-Brightness 18. Off-Time
• Head-Decelerating 19. On-Brightness 20. On-Time 21. Off-Brightness 22. Off-Time
• Tail-Lights-On 23. On-Brightness 24. On-Time 25. Off-Brightness 26. Off-Time
• Tail-Lights-Off 27. On-Brightness 28. On-Time 29. Off-Brightness 30. Off-Time
• Tail-Accelerating 31. On-Brightness 32. On-Time 33. Off-Brightness 34. Off-Time
• Tail-Decelerating 35. On-Brightness 36. On-Time 37. Off-Brightness 38. Off-Time

There are also settings for the behavior for each mode. They are consolidated into one register using bitwise operations.

39. Light-Behaviors
    • 0-1: Head-Lights-On
    • 1-2: Head-Lights-Off
    • 2-3: Head-Lights-Accelerating
    • 3-4: Head-Lights-Decelerating
    • 4-5: Tail-Lights-On
    • 5-6: Tail-Lights-Off
    • 6-7: Tail-Lights-Accelerating
    • 7-8: Tail-Lights-Decelerating

Each Behavior can have the value as follows:

0. Inherit (): Inherit the value from Lights-On (If this is set for Lights-On, then behavior 1 is assumed)
1. Solid (Brightness): The light should be on at a constant brightness
2. Blink (On-Brightness, On-Time, Off-Brightness, Off-Time): the light should blink
3. Sweep (On-Brightness, On-Time, Off-Brightness, Off-Time): the light should smoothly change brightness.

Parameters used are in parentheses.

Data

These are not settings, but Long Term Variables (LTV), some are read only, while others are writeable.

40. Trip-Distance
41. Trip-Max-Speed
42. Trip-Ave-Speed
43. Odometer-Distance Read Only
44. Odometer-Max-Speed Read Only
45. Odometer-Ave-Speed Read Only