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Unread 22-01-2016, 18:31
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Re: Clarification on COTS Embedded Systems

Quote:
Originally Posted by ChuckDickerson View Post
I am confused by your response. Hardkernal/Odroid most certainly does sell a battery designed specifically for multiple Odroids. Whether or not it is crammed inside a case or taped to the outside or otherwise mounted is irrelevant.

http://www.hardkernel.com/main/produ...=G137508214939

Regarding the need for brownout protection that can be mitigated easily using a buck/boost DC-DC converter like this one:

http://www.mini-box.com/DCDC-USB?sc=8&category=981
The battery you have linked provides the power to the real time clock (RTC) so that once you set it manually or by NTP it keeps time. It is not intended to run the unit. Even though it can't run the ODroid totally it would still break the rules I provided above. You can only use a battery if the battery was in the COTS system by default. You can't fabricate it in. There was a long topic about this on ChiefDelphi more than 1 year ago regarding the Raspberry Pi. If the ODroid has the battery on the PCB you might get away with it instead it just has a connector. Even though it only powers part of the PCB it didn't come on the PCB. It's not different than if I stack a bunch of batteries in a box onto the power input.

You are correct about the power supply. For example the ODroid XU4 draws 5V at 3A with a Belkin WiFi, cheap 2.4GHz wireless keyboard and mouse and a Logitech 920C (I measured with a Fluke multimeter on 100ms max record). It comes with a 5V at 5A power supply for the wall (it has 3 USB host ports each rated at the full current rating). So a DC/DC converter buck/boost or other combination in the 25W-100W range will work. In the case of that unit be sure to turn it down from 12V to 5V because the default is 12V and it will not end well for the ODroid.

Also as mentioned in other topics: the old DC/DC converter for the D-Link can power an ODroid XU4.
It is rated at 5V at 5A.
It drops out at 8V from the battery.

Be careful to rig up a way to turn off the ODroid neatly when you kill the robot master breaker.
Linux generally will tolerate a hard power off, but it's best not to fsck it over and over.

Last edited by techhelpbb : 22-01-2016 at 18:45.