GTA04 Block V4

Ian Stirling OpenMoko at
Tue Aug 12 04:12:33 CEST 2008

Werner Almesberger wrote:
> Ian Stirling wrote:
>> Interestingly, some of these devices also offer USB. Exactly why this is  
>> interesting, I'm unsure :)
> USB would allow us to use such an MPU to implement most of the key
> functionality of the debug board, i.e., JTAG and the serial console.
> Granted, it would be a bit of work, but I'd be rather happy if we
> could get rid of the debug board and its fragile attachment.
> Unfortunately, it's still uncommon for these MPUs to have a mode for
> loading their firmware over USB. The only one I found is the AR91SAM7,
> but that one is a bit inflexible in other regards. 

Not USB no. Documents 
'system memory mode'.

And confirms it can't be 
This is a serial bootloader.

I think you can always mass-erase the chip though, so a USB bootloader 
would not survive malicious users.

> Alternatively, a "foolproof" protection of a boot area in Flash that
> could in turn set up USB would be suitable. But I haven't found that
> either.
> My wish list would look like this:

As I read it, some of the STM32 family tick most of these.
Arm, one supply (2-3.6), most IO 5V tollerant, quite low current - 14uA 
remembering. Not quite dirt cheap, $3.5 at 1K, and digikey doesn't seem 
to stock the BGA parts.

Missing wide supply range, single crystal (though you can supply 32KHz 
clock to other stuff) (or single crystal if you don't want USB or RTC, 
no crystal if you don't want either)

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