Is an SD/MMC card more robust than a CF card?

Oct 11, 2006 6 Replies

I have a datalogger in a truck that I want to add a card reader to.



I was gonna use a CF card, but told that it was not as robust cause the pins in the reader wouldn't withstand the environment (dirt, grit and other stuff). Then I was told to try it with a MMC or SD card.



I haven't seen anything online about a CF card not being as robust.... Do you guys know of anything?


-Mercy



Yes, the CF pins/sockets are easy to damage. It's just thin copper alloy foils and wires. Use the IDE-CF adapters, the IDE connectors and cables are well tested and much stronger than CF. We usually put the CFs in the adapters and never take them out. Once they are connected, the CF pins/sockets won't be damaged. IDE-CFs are easier to program than MMC/SD.

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I would still be concerned about vibration and dust wearing away on those tiny CF pins and sockets in a truck environment. SD with its 9 solid flat connectors and good wipe action seems like a much better idea. Drivers are available for most micros that make the interfacing pretty painless.

Regards, Adrian Jansen adrianjansen at internode dot on dot net Design Engineer J & K Micro Systems Microcomputer solutions for industrial control Note reply address is invalid, convert address above to machine form.

That's not really a problem. Once it's in contact, dust won't affect it much. CF (pins and sockets) can take 10G (it's in the spec) of shocks and vibrations. The weakness is insertion aligment, rather than anything else. A slightly bended pin can just punch out the socket foil. That's why we never remove the CF from the socket at all.

It's just thin copper

Better yet, for heavy industrial usage, I'd recommend Disk-on-Modules

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Solid state/flash IDE drives. Can't get easier to use than that. The downside is that they are a bit more expensive than either CF or MMC/SD.

Dust can be a problem if its not excluded by the plug/socket construction. We ran into this years ago on gear in tractors - admittedly then a very bad environment. Had many failures on ordinary DIP ICs mounted in both wipe and turned pin sockets. Dust would enter the socket, and vibration would wear away the pins to the extent that you could tap the boards on the bench, and several ICs would simply fall off, minus their pins.

Regards, Adrian Jansen adrianjansen at internode dot on dot net Design Engineer J & K Micro Systems Microcomputer solutions for industrial control Note reply address is invalid, convert address above to machine form.

That's not a problem for CF. The pins are round and tight fit into the round openings. Some new CF has openings slightly smaller than the pins, and be enlarged to the exact size when inserted. If you never remove the CF from the adapter, the seal will be good. Furthermore, we put aluminium cover around the pins to protect them from accidental bending, and chemical dust as well.

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