GTA04 X-Loader

Issue 279: System does not startup on USB-Power but w/o battery or empty battery

Reported by Nikolaus Schaller, Aug 24, 2011

default USB supply current is in the 60-70 mA range.
As soon as MLO and/or U-Boot are loaded, the system draws more 
current and therefore the supply breaks down.

A potential fix could be to add code to MLO/XLO to initialize the 
USB power controller to provide more current (e.g. 200-300 mA). This 
allows the device to boot and finalize further initialization.

If this approach works is unclear.

Reasons for doubt:
* MLO code may draw more than 50 mA
* other components may start up and draw additional current 
(display, backlight, UMTS module)
* bulk capacitor has 100-200 uF but this may not be enough to 
stabilize the VBATT while the power controller is being reprogrammed

Comment 1 by Nikolaus Schaller, Nov 29, 2011

Well, in many practical cases it works.

Nevertheless, I have seen in the git logs of the  OpenPandora 
X-Loader that it also does something to enable early USB charging.

Comment 2 by Nikolaus Schaller, May 13, 2014

For the records, there is a disabled patch in our source:;a=blob;f=board/omap3530

Comment 3 by Nikolaus Schaller, Mar 19, 2015

For the OpenPandora charger patch compare:;

Comment 4 by Nikolaus Schaller, Dec 18, 2017

Has been fixed by adding a "charge auto" command to U-Boot 
and execute it by boot.scr.

Anyways, we don't have a separate X-Loader source tree any more. 
This is nowadays part of the U-Boot code and called "SPL".

Comment 5 by Nikolaus Schaller, Dec 18, 2017

Status: Fixed

Created: 12 years 9 months ago by Nikolaus Schaller

Updated: 6 years 5 months ago

Status: Fixed