[Openec] Ladies and Gents, we have a "brick with a monitor"

[Richard A. Smith]

Frieder Ferlemann wrote:

> - the UART RX is not working here if WLAN is not powered.
>   RX/BAT_LO (CN24,3 CON2,45) seems clamped at about 2V
>   if WLAN is powered off.
>   Is that known and is CON2,45 within absolute maximum ratings?

On your B1 BAT_L0 goes to an input on the WLAN module.  If wlan is not 
powered then you are driving an un-powered pin.  So your results are 
somewhat expected.  That signal moved in later revs.

You will need to enable WLAN or you won't get very far.  WLAN enables 
the source for the 3.3V rail.  Most of the other voltage rails come from 
the 3.3V rail.

> - the ec-dump.fth like dump locks near the output of the
>   content of 0xff50.

Interesting.  0xff50 is not documented as anything.  Its in the general 
purpose wakeup section.  Perhaps you are tickling some undocumented 
register that crashes things?

On my C1 (KB3700B) and a B4 I can read 0xff50 with indexed IO via OFW 
and the EC still responds to battery insertion/removal.  Not sure how 
similar that is to a read via the 8051.

> With the monitor it might be possible to power up the XO?

I think so.  When you get it right you should see some post codes.  The 
EC can decode post codes so you can watch for those.

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