Re: [openpsion] Everything so far...

[<edw...@ti...>]

Well, to be honest I'm not really sure whether SDIO is possible. It 
seems that SDIO uses SPI mode (rather than the full 4 bit SD) so it 
might be possible, but I can't find this information conclusively. But 
you can still add an SPI based wifi chip (like this http://www.whiznets.
com/index.php/Wireless-LAN-Modules.html) even if it is not possible to 
do SDIO. I'd imagine this is faster than using a serial port based 
bluetooth/wifi chip. I think the 5mx might be able to do 256K baud on 
the serial port  (in Linux only), but I'm not certain (think someone 
mentioned this on the mailing list once). I have a hunch you'd get much 
faster speeds using SPI over GPIO.

I wouldn't expect it to be fast as memory storage though, probably not 
even close to CF speeds, but I really have no idea what kind of speeds 
you can expect (I haven't actually done this, I just know it's 
possible)! SPI is 1 bit in, 1 bit out, instead of the 4 bits you get 
with full speed SD access, and there is also the added overhead of the 
bit-banging driver (not much, but something). But it is still better 
than nothing!

Another thought; given enough CS lines (and I just checked... there 
are 7 GPIOs from the serial port: RTS, DTR, TXD, DSR, DCD, CTS and RXD) 
you could add multiple SPI devices... like 2 SD cards, or a wifi chip 
and an SD slot, and still have a basic RX+TX, no handshaking, serial 
port.

Ed

>----Original Message----
>From: ax...@gm...
>Date: 16/09/2009 7:26 
>To: <edw...@ti...>
>Cc: <jo...@le...>, <ax...@gm...>, <linux-7110-
ps...@li...>, <vig...@gm...>
>Subj: Re: [openpsion] Everything so far...
>
>Ed, 
>do you know if it's possible to work with SDIO cards using bit-bash 
driver? That would be a fantastic mod. If not, what kind of speed one 
can get for the regular SD card with bit-bash driver? Slower than with 
our CF slot or faster?





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