Qualcomm Snapdragon, DragonBoard 410c Fire Up at World Maker Faire

Re:Qualcomm Snapdragon, DragonBoard 410c Fire Up at World Ma... by jepler on Saturday September 26, 2015 @12:28PM (#10283499)

I only have a kill-a-watt for measuring power consumption. I am using a brandless Universal AC Adapter at 15V and I do not know its efficiency. I'm not aware of any ability to monitor power consumption directly on the dragonboard.

    Idle, text  1W 5VA
    Idle, X     2W 5VA 
    1CPU, X     3W 7VA
    2CPU, X     4W 9VA
    4CPU, X     4W 11VA

(CPU load generated by dieharder statistical randomness test on AES_OFB CRNG, dieharder -a -g 205)

Incidentally, Dieharder's AES_OFB CRNG (which I don't think uses the AES instruction set on intel) runs at 5e6 randoms per second per thread on dragonboard, compared to 2.5e7 randoms per second per thread on my 3yo 2-core/4-thread i5 laptop at 2.6GHz, to make just one simplistic comparison of CPU speed.

(edited to try to fix formatting)

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Re:Qualcomm Snapdragon, DragonBoard 410c Fire Up at World Ma... by tbr on Saturday September 26, 2015 @12:35PM (#10283518)

The board should be prepared for current measurement instrumentation. Details can be found in the schematics, that finally got published after they were sitting around on them for a few months.

Not publishing the schematics and a couple of other things are actually violating the grand LINARO 96boards compliance spec, but nobody there seems to really give a f...art.

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Re:Qualcomm Snapdragon, DragonBoard 410c Fire Up at World Ma... by jepler on Saturday September 26, 2015 @01:35PM (#10283724)

I researched the 410c schematic as suggested by tbr. I can measure the input voltage at J1 and measure the input current as a voltage across the .1Ohm resistor r77 or pads 1 and 2 of j10 (both on the bottom side of the board).

    Idle, text  15.2v   115mA  1.75W
    Idle, X     15.2v   124mA  1.89W
    1CPU, X     15.2v  ~180mA  2.74W
    2CPU, X     15.2v  ~240mA  3.65W
    4CPU, X     15.2v  ~260mA  3.95W

All of my CPU loading scenarios had much more variable current readings, I tried to record the highest value I saw on a multimeter with a ~.5s update time over 10+ seconds.

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Re:Qualcomm Snapdragon, DragonBoard 410c Fire Up at World Ma... by keenerd on Saturday September 26, 2015 @12:56PM (#10283585)

Thank you! That does put an upper ceiling on power draw. (When I measure, I either use a bench PSU or splice a DMM in line.)

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