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EMX vs G120 Power Consumption


I’ve just done some current draw tests on our EMX and G120 boards, with interesting results. The boards are basically identical, except for the modules. They have a 16x2 LCD with back-light, microSD card, Hi-Res A-D chip, voltage reference and a couple of LEDs.

Tests were done with LCD back-light at around 25%, LEDs off.

Running identical code and current SDK.

EMX (running) 170mA
EMX (hibernate) 28mA
G120 (running) 179mA
G120 (hibernate) NA (crashes)

Surprising, as I thought the G120 was going to be faster and use less power, while it actually seems marginally slower and consumes slightly more power.

We use a 4000mA lithium cell and a LDO linear regulator (switchers don’t work in our magnetic field), so assuming we can get approximately 50% capacity out of the cell, we should get around 11 hours runtime, or 70 in hibernate. Just have to get the G120 to hibernate now.


That makes sense. Something like a Pi calculation would use on-chip/cache RAM, while my timing was for boot-up, which would of course be reading in from external memory, and so slower.
I wonder why the power consumption is up, though? I read a post from Gus predicting the G120 would draw 50-80mA.