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USBClient DP with USB + External Power = Fail


#1

I have a spider with lots of modules plugged in. Need lots of power.

[ol]When I plug in USB-only, the device will crash/reboot when it does something that draws too much power
When I plug in External-Only (12v 1A) the device runs as expected
When I plug in BOTH USB and External power, the device freezes where even the reset button does nothing. (also T35 screen goes totally white, pixel filled)[/ol]

1 and 2 are expected behavior. But can you see the dilemma with #3? If I cannot connect USB, I cannot debug the device!


#2

I have 1.2. Is there a work-around? Then again, both voltages aren’t the same in my case. Still, its behavior clearly messed up.


#3

I would check schematics for both versions. It can be just a matter of adding a simple component or two.


#4

Hmmm… mine might have the same problem. If I plug my USBClient DP in with both USB and external power at the same time, then the LED on the DP unit would dim and flicker and my app would stop working. But if I use only the external power or the USB power, then it works fine. (I do not use modules that uses a lot of current).


#5

Im seeing a reasonable 4.8v and 3.2v on the pins respectively no matter what I have plugged in. I don’t know if voltage is the prob, but maybe noise when they’re both plugged in? I have no equip to test for that.

I tried following the schematic but didn’t have time to comb over every little thing on my board. I did notice the schematic is pretty recent compared to the pic of the v1.2 board online. Anyone from GHI that can comment on what changed? What needs adjusting here?


#6

We changed how the super diode is configured. So it always uses the power source whenever it is available instead of using the higher voltage.


#7

Can it be done with 1.2 modules?


#8

it would be very difficult to hack the 1.2 modules. Typically, a different USB port on the PC solves the problem.


#9

Ok. Thank you.