Openmoko Bug #1682: Neo turns off before reaching X

Openmoko Public Trac bugs at
Fri Aug 1 07:43:38 CEST 2008

#1682: Neo turns off before reaching X
 Reporter:  queen6           |        Owner:  openmoko-kernel
     Type:  defect           |       Status:  new            
 Priority:  high             |    Milestone:  ASU            
Component:  System Software  |      Version:  GTA02v5        
 Severity:  normal           |   Resolution:                 
 Keywords:                   |     Blocking:                 
Blockedby:                   |  

Comment(by werner):

 This may be the VB_SYS bypass capacitor: GTA02v5 has a very small
 capacitor to
 stabilize the system voltage. It's perfectly conceivable that a different
 pattern of load changes could cause VB_SYS to break down before the USB
 adjusts its output.

 If you like to play with a soldering iron, you could try to modify a USB
 and put a big capacitor (I'd try about 100uF) between GND and VBUS. The
 setup won't be USB-compliant (USB 2.0 section, page 177, only
 10uF, and we already exceed that by a considerable margin), but you can
 get away with that.

 You may also be able to get better results with a shorter or better
 USB cable, since it may reduce the voltage drop from host to device. Also
 different host may perform better or worse.

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