[coreboot] SPI clock rate

[Andreas Galauner]

On 7/5/11 3:02 AM, Peter Stuge wrote:
> Andreas Galauner wrote:
>> Yep, I just found the pinheader. Seems to be 1.27x1.27mm.
>> I also created a support ticket for the pinout on Sapphire's website.
>> It would be nice if they give that to me, but I really doubt it.
> 
> Did you check that it's not documented in the manual already?
> 

Yes. It's not in there.
They labled the POST-Code display, they have huge tables of really cool
POST code error message explanations and on one pciture of the POST
display there even is a header on those SPI pins installed, but there is
nothing about the pinout.

> 
>> I'll try to measure the pinout tomorrow with a multimeter.
> 
> Sure, that will work fine. Each pin will be directly connected to a
> pin on the flash chip.
> 

I'm just asking myself all the time what to do with the supply lines.
If the board is without power or in standby, I obviously need to supply
power (assuming that there is a VCC line on the header), but if it is on
and I just pull the reset line before starting the programming, this
sounds a bad idea to me.
So the user needs to specify, if he wants to supply power or not, right?

> 
>>> What do you mean by AVR? It's relevant for much of what you write.
>>
>> Oh, sorry. I mean those Atmel AVR microcontrollers.
> 
> Yes Atmel, but "AVR" says nothing about which family of devices you
> mean. If it's the wee small 8-bit ones I wouldn't bother, on the
> other hand if you have a toolchain then sure, why not!
> 

I think I'll get one of those Olimex boards. I always wanted to do
something with ARM CPUs and it makes porting the firmware to your
suggested final device much easier. Nice idea, BTW.

> 
>> I haven't done very much with SPI flashes until now. I know how the
>> physical protocol works and used it a few times in some smaller
>> microcontroller projects, but I definetely would want to take a
>> look at it.
> 
> It's fairly simple. Pick up a flash chip datasheet and you've
> actually already got mostly all you need to know. The flashrom source
> code can also help, but be careful to not get unneccessarily confused
> by the code to deal with different types of SPI bus masters in there.
> 

I just had a look at some datasheets.


> 
>> And the development board is easily available and cheap in Germany.
> 
> Yup. What city are you in?

Aachen or Cologne. Choose one ;)


Andreas