Re: [Gc-linux-devel] USB port: schematics and PCB

[Rob R. <ro...@re...>]

I've picked up this excellent idea, and designed a schematic and PCB  
for this USB host interface. Links to the schematic and PCB are on  
the wiki: http://www.gc-linux.org/wiki/EXI:USBHostAdapter . I just  
have to wait for the company where I'm doing my internship at the  
moment to do their next PCB panel, then I can stick some of my PCB's  
on for free.

Also, I'm currently working on a ethernet controller to replace the  
hard-to-get BBA. It will use Microchip's ENC28J60 SPI ethernet  
controller.

I'm starting with the Linux driver modules, but I'm not sure how to  
do the probing/detection. The current EXI driver does (if I  
understand the source correctly):

-select device
-output 0x0000 (request ID)
-read 16 bit ID
-deselect device

-if the read ID is 0 (which happens with MMC/SD cards apparently),  
and the device is on one of the memory cards, EXI_ID_NONE (or  
something) is returned, and all exi-device drivers claiming to  
support that ID are then probed.

Now the problem is, with both the MAX3421 and the ENC28J60, 0x0000  
means just 'read register 0', which could be anything (might be 0x00  
after reset?). Also, both these parts do not have a 'Request ID'  
command, so there's no straight-forward way to probe them. So how do  
we identify these parts? Or could there be an easy way for the user  
to set the exi channel/device manually? Module parameters? What about  
the ethernet controller that might be used to mount the root fs?

I guess there are more experienced driver programmers on this list  
who could tell me the way to go.

Regards,

Rob Reilink



Op 20-mrt-2007, om 3:26 heeft Albert Herranz het volgende geschreven:

> PATx box <patx_boite <at> hotmail.com> writes:
>> I read a bit this morning before ordering parts and the MAX3421  
>> will be
>> needed instead of the MAX3420 witch is for peripheral devices  
>> only ...
>
> Yes, I noticed that too.
>
>> I ve ordered parts and i will make a shematic based on figure 21  
>> (datasheet)
>> and the memcard pinout...
>
> Remember to wire up the irq line too. We'll need that.
>
> My biggest concern is that the controller doesn't support a 32MHz  
> clock
> (according to the data sheet it supports a maximum of 26MHz), so  
> we'll have to
> run the SPI bus at 16MHz, unless someone figures out how to program  
> the EXI
> interface to a intermediate clock speed.
>
> I think it would be a good idea to keep all the details of this  
> mini-project on
> the project's wiki. I've started a page specially for that:
>
> http://www.gc-linux.org/wiki/EXI:USBHostAdapter
>
> Cheers,
> Albert
>
>
>
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