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Does anyone know between GPS, compass heading and accelerometer which uses the most amount of battery (or how they compare relatively?)

I'm assuming somewhat naively it's:

accelerometer < compass heading < GPS

but I can't find anything to substantiate or refute my intuitions.

Clarification: I'm curious as to how it performs specifically on an iPhone.

Rio
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2 Answers2

9

Well it really depends on the device. A GPS with an active antenna will consume the most power. Accelerometers and compass usually only draw milliamps when running. Generally your order is correct.

Specifically to the iPhone

  1. GPS: 4mA (Assuming it runs on 3.3V. I cannot find the datasheet)
  2. Compass: 1.2mA
  3. Accelerometer: 0.25mA
Axis
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2

Your order is correct.

  • MEMS accelerometers are based on measuring capacitors (this really do not have any consumption with an ADC).
  • Magnetometers (compass) are based on measuring a ferro-resistive material, which have to be excited with large short-time current pulses + ADC. Therefore the consumption should be a little bit higher.
  • GPS involves more than just reading an ADC, the signal has to be processed (generally by a FPGA or ASIC), therefore the consumption is higher.