[flashrom] [coreboot] Dual flash chip mod

[Carl-Daniel Hailfinger]

[Fullquote because your flashrom related reply didn't end up on the
flashrom list.]

On 29.07.2009 18:17, Peter Stuge wrote:
> Carl-Daniel Hailfinger wrote:
>   
>> this is no longer coreboot related.
>>     
>
> I think this is highly coreboot related.
>
>
>   
>>> A few cm should be fine but keep them as short as possible.
>>>
>>> You need pins 2 (7 8) (9 10 11 12) 13 14 15 16 17 24 25 28 29 31 32
>>>
>>> Hm, that's 12 but some are the same signal. The ID pins and MODE can
>>> probably be tied to either VDD or VSS but check their connections on
>>> the original chip first.
>>>       
>> If we're dealing with FWH chips on ICH, you can solder both chips
>> on top of each other with all pins except ID0. ID0 needs to be
>> connected to a switch so that exactly one of them is high and the
>> other one is low.
>>     
>
> Yes, good point, the CE in this case is ID0, and it should be
> switched. ID pins are internally pulled-down so the switch circuit
> actually becomes trivial. Disconnect original ID0 from mainboard.
> Connect middle contact of switch to VDD via a 1k resistor. Connect
> each side contact of switch to ID0 on the respective chips. The three
> leads to the switch can be pretty long.
>
> If they are PLCC chips it isn't very practical to solder two chips on
> top of each other, because the chip leads bend in under the chip and
> do not reach the top. Every lead on the upper chip would have to be
> bent to continue straight down to maybe reach the leads on the lower
> chip. I don't know if the leads are actually long enough to make that
> work. Also needs a few mm for the chip package on top of the existing
> chip of course. Often it's easier to put the second chip somewhere
> else on the board, and run wires. Yes, that needs a little more work.
>
>
> //Peter
>
>   


-- 
http://www.hailfinger.org/