[U-Boot-Users] Help with serial port set-up for PPC 8540

Wolfgang Denk wd at denx.de
Tue Jul 13 00:30:31 CEST 2004

In message <20040712212957.88820.qmail at web90006.mail.scd.yahoo.com> you wrote:
>    I am trying to write an Assembly code , just to
> set-up the UART , so as to send a few characters via
> the serial port.

Why? There is a full-blown serial driver available written in  C?  Is
this intended as a replacement for a missing BDI2000? Save your time,
abd  buy  the  BDI2000 _now_. Other wise your time is just wasted, as
you will buy the BDI2000 later anyway.

>     I just have set-up the necessary registers for
> UART and as I am not doing any high level coding I
> havent set up the MMU  , TLB etc. But my code doesnt
> seem to work !!!

Forget it. U-Boot was explicitely  designed  to  bring  up  a  serial
console  port  as  early as possible during initialization. OK, there
are a few things that  could  be  saved  before  running  the  serial
driver,  but  this  is  just a tiny piece of the code you need to get
right before you will see the first character on the serial line.

Don't try to re-invent the wheel.

>     I assumed that that CPU would direclty read from
> the Flash .I am new to this and so I need some advise
> of what all have to be done during board bring up, or
> where should I look for such documentation.

Use the existing U-Boot code. Attach a BDI2000 and just type "ti"  at
the telnet prompt, or "d/i $pc" + "si" in GDB...

Best regards,

Wolfgang Denk

Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
"The good Christian should beware of mathematicians and all those who
make empty prophecies. The danger already exists that  mathematicians
have  made a covenant with the devil to darken the spirit and confine
man in the bonds of Hell."                          - Saint Augustine

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