[beagleboard] Using 1A USB charger instead of 5V DC adapter

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1

You should be bale to use the charger. The board will take what it needs which is 500mA. If you add a heavy load device to the USB, it will go over that, but I would expect the charger to handle it. USB current limit is set for charge mode by default.

Gerald

2

Hi,

#### WARNING! ###

If the charger contains a certain kind of charge-logic for a certain
kind of acculmulator, the output voltage may depend on what the
charger thinks what the correct charging curve is.
The may result in a constant current (2A) and a varying (higher)
output voltage!

#### WARNING! ###

Dont be afraid...thats Only my two cent. Your voltage may vary.. :wink:

Kind regards,
mcc

Gerald Coley <gerald@beagleboard.org> [13-06-02 15:44]:

3

I am not afraid. The board is in control as it how much it takes and it does not take more than it needs. Not the charger.

Gerald

4

On the BeagleBone, it does. It limits it to 600MHZ on USB. The BeagleBone black, makes not such limit under Angstrom. Other distributions may make such a limit.

Internal circuitry makes no limit of current base don the fact that it is under USB power.

Gerald

5

William, From my own experience using USB 3.0 and debian on the bbb is that the black will scale processor frequency based on load. In debian, when idle the processor will sit at 300Mhz. When loaded, the processor will scale up to 1Ghz.

As test though using:

#include <stdio.h>
#include <unistd.h>

int main(int argc, char **argv)
{
unsigned int index = 0;
unsigned int mSeconds = 500;
int returnCode;

while(1)
{
if((++index % 10240) == 0 ){
returnCode = usleep(mSeconds);
index = 0;
}
}

return 0;
}

The processor will load up( in this case 60% load for this app ), but the processor stays at 300Mhz. With the delay code removed, the processor is fully loaded ( up to around 99.5% for the app) and the processor will reach 1Ghz.

I believe Gerald had said previously that what you say is how it is supposed to work, assuming the distro in question was written to deal with this. However since he has just replied as I am writing this, I am sure he can answer that himself.

6

This is correct. But, it is not based on USB or DC power. Just processor load.

Gerald