[Openec] Ladies and Gents, we have a "blinking brick"!

[Richard A. Smith]

Frieder Ferlemann wrote:

> 
> Strangely this does not result in the PowerLED toggling at the same
> intervalls (screenshot appended).

I bumped up the unapproved size limit for the list to 200k.

> The long high intervall there repeats about once every 5 seconds
> (probably a reset issue). Yet the shorter intervals are not equidistant
> either.

Odd.  One possibility is that access to the SPI flash is arbitrated 
between both the LPC bus and the 8051.  The in a 3700 CPU gets priority. 
(3700B fixes that).  We have had cases were the CPU can starve the 8051 
  of ROM access cycles and cause watchdog time outs and other timing 
issues.  So if the CPU is somehow resetting or (running a big noop loop) 
and every 5 seconds and tying to access the FLASH ROM then it might be 
causing this.

Use another channel on your scope and see if the LPC LFRAME signal is 
getting asserted a lot during the long pulse.

> Another flash related topic: during my updating the OLPC I have
> lost the content of the uppermost 1 kByte of the flash.
> I backed it up first (at least I thought so) with OFW
> to an USB stick (IIRC with read-flash u:\flash.bin)
> but when I tried to reinstall that image it turned out
> to be only 1047552 bytes (instead of 1048576 bytes) long.
> Is this known/intended?

Hmmm... I can't really say that I've used read-flash.  Perhaps it did 
not save the manufacturing info because the write procedure reads that 
from the laptop and merges it into the image you are about to write.

-- 
Richard Smith  <richard at laptop.org>
One Laptop Per Child