3 ms·

What is the power draw like at idle and load?

by keenerd 11y ago

jepler 11y ago
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)
- tbr 11y ago
  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.
- keenerd 11y ago
  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.)
- jepler 11y ago
  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.

What is the power draw like at idle and load?

by keenerd 11y ago

What is the power draw like at idle and load?

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)

tbr 11y ago
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.
keenerd 11y ago
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.)
jepler 11y ago
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.