Fwd: Adding a system management MPU

Wolfgang Spraul wolfgang at openmoko.com
Thu Mar 20 07:53:32 CET 2008


This thread about a system management PMU accidentally happened on an  
internal mailing list.
I am forwarding the whole thread to openmoko-kernel.
(next I will try to get that internal mailing list shut down, but I  
better not say who defends it all the time ;-))
Wolfgang

Begin forwarded message:

> From: Andy Green <andy at openmoko.com>
> Date: March 19, 2008 4:28:45 AM GMT+08:00
> Subject: Re: Adding a system management MPU
>
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> Somebody in the thread at some point said:
>
>>> and word from you guys that a 2443 vs a 6400
>>> might be about the same work
>>
>> We don't know that yet :-( A lot would depend on what MCPs Samsung  
>> can
>> give us. My latest (woefully incomplete) status on this is:
>>
>> 2443: zero information about MCPs
>> 6400: has MCPs, but not very useful ones (too much Flash, too  
>> little RAM)
>
> 128MBytes of DDR that is in the 6400 MCP can be OK... "too little" for
> what?  We can expose the OneNand to the user one way or another, I  
> guess
> it allows not having any SD slots on variants to be considered.   
> Asking
> about which MCPs actually exist for us would be a big question for
> Samsung as you say.
>
> In terms of work the last data we got says they upleveled their BSP to
> 2.6.21 already from 2.6.16, so the distance from that to a working
> 2.6.24 solution is quite a bit smaller.
>
>> It would also be good to have some information on the Siemens  
>> telephony
>> modules, at least basic parameters like power requirements and  
>> physical
>> size. The underlying question is: would it make sense to expect  
>> roughly
>> the same form factor for a UMTS and an EDGE device, or does this  
>> make no
>> sense at all ? (E.g., because the UMTS module is five times the size,
>> UMTS and EDGE modules have completely different geometries, or the  
>> need
>> an entirely different power supply architecture anyway.)
>
> Yes.
>
>> directory tree (like /space/docs of varaha)
>
> That has worked great for me, there's already a 6400 dir in there.
>
> Having a slow cheap micropower flash MPU on there into which we
> implement all logic and sequencing we want for the device while the  
> CPU
> is unavailable can solve a few issues at once.
>
> Particularly as we established we are getting rid of U-Boot and have a
> minimal bootloader, if we wake the CPU it means waking into Linux one
> way or another before anything complicated gets done.  We can use this
> MPU to manage power and button/touchscreen/connector events, motion
> sensors, battery HDQ, PMU, LEDs in a central, consistent and complete
> way without needing to bring the CPU into it and without any dead time
> while we wake the CPU.
>
> Something along these lines (6.8mm x 6.8mm footprint) $3.10 / 100
>
> http://focus.ti.com/docs/prod/folders/print/msp430f2272.html
> http://www.ti.com/lit/gpn/msp430f2272
>
> - -Andy
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