[OLPC-devel] Embedded Controller and Serial Flash ROM

[Ray.Tseng at quantatw.com]

Carl,
	My reply in <Ray>

Ray Tseng 5/30/06	

-----Original Message-----
From: Carl-Daniel Hailfinger [mailto:c-d.hailfinger.devel.2006 at gmx.net] 
Sent: Tuesday, May 30, 2006 10:33 AM
To: Ray Tseng (曾文瑞)
Cc: devel at laptop.org; mfoster at laptop.org
Subject: Re: [OLPC-devel] Embedded Controller and Serial Flash ROM

Hi Ray,

thanks for your explanations.

Ray.Tseng at quantatw.com wrote:
> The size will grow rapidly, please reserve 64K for final EC.

Can we be sure that 64k will be sufficient for the EC code?
<Ray> Yes

> The EC  takes care 1) Event detect 2) Power on/off
> 3) battery management 4) Keyboard/mouse etc. 

Do you have any numbers on which part is the biggest? I assume battery management.
<Ray> the codes are mixed, we don't have the numbers.
Is event detection and keyboard/mouse needed before the BIOS is run? If not, can we split that part away and load it later?
<Ray> let me explain the power on sequence:
(a) AC plug-in
(b) EC fetch EC code from SPI ROM and execute
(c) EC detect power on event
(d) EC power on the system
(e) CPU fetch BIOS code from SPI ROM and execute
(f) CPU shadow BIOS to shadow RAM
(g) CPU fetch BIOS code from shadow RAM and execute

> The EC code control the power on sequence, it run before the BIOS The 
> EC code can not be compressed.

That's unfortunate. Do you write the EC code directly in assembly or do you use a compiler like romcc?
<Ray> in C 

Regards,
Carl-Daniel
--
http://www.hailfinger.org/