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Re: PCMCIA interface or CompactFlash or general I/O


I am working/testing/implementing a simple interface for CF cards, the board 
is ready, just testing the hardware and than implementing the software.
PCMCIA Flash and CF Cards have a "real" IDE interface option (see specs i.e. 
on Mitsubishi web site), so I use the IDE interface from ETRAX

- using 2 port bits for detecting card insert signals
- if needed Power select lines. I am using only 3.3 volts (all newer cards 
should support this) so I have ingnored this.
- 1 port bit and logic for switching power on/off for PC/CF card (also I am 
using it for enabling data and control drivers (+ some resistors for default 
logic level)

As I don't need the full PCMCIA/CD card specs I just want to implement the 
detection of Card insert lines

If possible on ETRAX I will use ATA driver as kernel module. Than it should be 
very easy loading and unloading ata driver and thus FAT file system on 
detecting card inserted/removed. This could be implemented as a daemon which 
just monitors the the status of card inserted/removed

A dangerous situation is given on writing to compact flash when removing but 
this is also not covered on standard pcmcia/cf card sockets.

This also occures when power fails on writing. I have covered this by 
implementig a 2 step power supply (1st stage 5 volt with huge charge 
capacitors and 2nd 3.3 volt) plus watching 5 volt. By undervoltage a NMI 
should generate a power down with first terminating the writing app, giving 
time closing files before 3.3 volt fails.

Hoping this gives you some ideas and may be someone likes to help in writing/
modifying driver/daemon (I am more hardware related and have most programming 
experiances with writing drivers in assembler for i.e. OS9/68k).

If someone wants to I will provide the schematic as PDF file.

Have a nice day

Heinrich E. Seifert
Consultant for QM & PM

Am Freitag, 16. Januar 2004 19:30 schrieb Kelly Murray:
> Has anyone added a PCMCIA interface to the etrax?
> The app notes say something about it, but is not specific.
> Looking at the docs the processor has parallel port I/O pins
> that could be used, but has anyone done that.
> Mostly I'm trying to get a wireless modem interface for the device.
> Another thought is to use the IDE interface, and a CompactFlash wireless
> card.  But I think the compactflash cards are actually pcmcia rather
> than real IDE.  Any input appreciated, the integration of the MCM is
> rather amazing, just missing a wireless interface!
> -Kelly Murray