Hardware Accelerometer

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±2 g Dual Axis Accelerometer with Ratiometric Outputs


Some of the TomTom appliances are fitted with a dual-axis accelerometer, which measures the forces on the device. This allows the TomTom to estimate speed and direction when it loses GPS lock, and thus perform "dead reckoning". The TomTom GO300 doesn't have this device, but the GO500,700,900 and 510,710 and 910 do? (please correct me!)

Edit by Bruce I think the original Classic GO was the only one of the early models to have an accelerometer


The specifications of the accelerometer device are:

  • Resolution better than 1 milli-g
  • Dual axis accelerometer fabricated on a monolithic CMOS IC
  • On chip mixed mode signal processing
  • No moving parts
  • 50,000 g shock survival rating
  • 17 Hz bandwidth expandable to >160 Hz
  • 3.0V to 5.25V single supply continuous operation
  • Continuous self test
  • Independent axis programmability (special order)
  • Compensated for Sensitivity over temperature
  • Ultra low initial Zero-g Offset


The chip works using the principle of a Wheatstone Bridge in order to self-compensate; it has a gas inside whose movement is detected by changes in temperature - one or more sides of the bridge will cool down, causing the temperature sensitive resistors to change the balance of the bridge.


Source-code for the driver is in the kernel trunk(s) ..../drivers/Barcelona/Acmeter/

The driver is accessible from the linux char device (preferred name 'acc') with major device number 120.

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