Experiments with the WiTilt 3 axis accelerometer

Wireless Tilt sensor "WiTilt V2.5" from Spark Fun Electronics.
Updated, June 2008: WiTilt V3
Written by Paul Bourke


WiTilt V2.5, Firmware V4.2 - Configuration Menu:
 [1] Start Tri-Ax detection (hit spacebar to stop)
 [2] Set Active Channels (XYZ Active)
 [3] Calibrate
 [4] Sensor Range (+/-1.5g)
 [5] Display Mode (Raw)
 [6] Set Threshold (Currently +/-0.0g)
 [7] Set Output Frequency (60Hz)
 [8] Set Bluetooth (Currently Inactivce)
ASCII data format

This is with threshold set to 0, coordinate entries are skipped if that coordinate values is below the threshold.

X=459  Y=503  Z=760 
X=452  Y=519  Z=755 
X=444  Y=512  Z=756 
:      :      :
:      :      :

  • Serial settings: 57600 baud, 8 bit, no parity, 1 stop bit. ps: this is "serial-over-Bluetooth".
  • Reset button sends two 0xE0 characters, use this to put it into send mode (1).
  • On the Mac OS-X, used ZTERM to set menu entries. Lots of other terminal apps for this, such as "screen".
  • Range is about 10m with the built-in mini antenna.
  • Setting up the Bluetooth serial device on Mac OS-X ....
    - Bluetooth module in system preferences, choose "Set up New Device", choose "any device"
    - Reset WiTilt, "BlueRadios" device should appear, passkey is "default".
    - Back on Bluetooth preferences select the 'BlueRadios" device and choose 'Edit Serial Ports"
    - Accept default setting of "BlueRadios-COMO-1", "Apply"
    - There is now a tty device "/dev/tty.BlueRadios-COMO-1" that can be opened like any serial port.
  • In normal operation, the RED power LED should flash with 1 second period, when bluetooth connected the green LED is on, when data is being transferred the second red LED flashes at the frequency of the data transfer (it will appear to be on constantly for data rates above 50Hz or so).
  • Manual as pdf file

Interface example

Blue cup

The final version in the intended cup. AAA batteries.

WiTilt Version 3

Version 3 is a significant improvement, at least for those who want a finished solution. There are some differences (refer to notes above):

  • The Bluetooth device now identifies it self as "Firefly-D9C8".

  • There is no passkey required.

The menus are the same as version 2.5.

WiTilt v3.0 - Configuration Menu:
 [1] Start Tri-Ax detection (Press any key to stop)
 [2] Set Active Channels (XYZ-- Active)
 [3] Calibrate
 [4] Sensor Range (1.5g)
 [5] Display Mode (Raw)
 [6] Set/View Threshold Values
 [7] Set Output Frequency (60Hz)
Manual for version 3

Rough and ready software used for original evaluation: witilt.zip