Re: [ECOS] PCMCIA Standard CIS access

["Lewin A.R.W. Edwards" <larwe at larwe dot com>]

> From what I understand, the card does not have to have power enabled in
>order for me to read it's CIS.  Correct?  If so, does anyone know what
>MIGHT be the problem with reading the CIS?  I keep getting a READ FAIL
>interrupt when attempting to read the Card Information Structure.  Is
>there maybe a standard reason in most PCMCIA controllers why this might
>happen?  I doubt it! LOL

You need to refer to the PCMCIA spec here. Don't quote me on this, and 
above all don't implement anything based solely on my say-so, but IIRC the 
powerup process goes something like this:

* socket power cut off
* when both card detect pins go active (indicating card fully inserted), 
wait for some period of time (defined in the spec) and check the LVD1/LVD2 
pin state to see what the card expects for Vcc.
* apply Vcc to the card and wait some period of time (defined in the spec) 
for the card to power up.
* read CIS.
* even if your card is an old flash device requiring Vpp=12V, you should be 
able to use it in read-only mode with no Vpp applied.

Most PCICs with integrated power switching will automatically cut socket 
power and tristate all outputs going to the socket when either card detect 
pin floats (indicating card at least partially ejected).

You most definitely do need to power the card in order to read its CIS. And 
it most definitely IS possible to damage cards by setting up the wrong 
supply voltages. It is also conceivable that you could damage PCMCIA cards 
by applying signals when the card isn't powered.

BTW, if the card is a CF card, it will always be safe (and always possible 
to read the CIS) by powering it up at 3.3V. CF cards by design must operate 
at both VCC voltages.

This is why I suggested Linux, since it will take care of all the PCMCIA 
details for you, and you wouldn't even need to write drivers for many 
common cards...


-- Lewin A.R.W. Edwards
Embedded Engineer, Digi-Frame Inc.
Work: http://www.digi-frame.com/
Tel (914) 937-4090 9am-6:30pm M-F ET
Personal: http://www.larwe.com/ http://www.zws.com/

"Far better it is to dare mighty things, to win glorious triumphs, even 
though checkered by failure, than to rank with those poor spirits who 
neither enjoy much nor suffer much, because they live in the gray twilight 
that knows not victory nor defeat."
(Theodore Roosevelt)