C-Data Solutions has a mini computer the size of a Compact Flash card. Yes, that’s right. The form factor of this Linux computer is that of a Compact Flash card. The solution uses a CF DAQ card as the main processor and you can expand for additional flexibility using the CF COMM cards.
The Compact Flash Computer utilizes Motorola’s Coldfire MFC5272 processor. The on-board flash memory file system provides storage for the operating system (ucLinux) and user applications. Expansion is via a 16 bit bus compatible with Compact Flash devices. Up to eight devices can be integrate into a system using the Bus Extension Unit (CF type II device).
Here are the impressive specifications to the CF Linux computer:
I ran into a situation the other day where my SD card was [all-of-a-sudden] write protected. I couldn’t format it, I couldn’t delete the files and I certainly couldn’t write to it. I checked the lock/unlock switch and still, no avail. I thought the card was a total loss.
It turns out, the SD card wasn’t the problem but the card reader was.
After some internet searching I found several solutions to the problem, but no one really explained what the problem was. So I thought others could learn on “why” their SD card was write protected and giving problems.
First off, lets take a look at the SD card reader itself. Below is a typical SD connector found inside most SD card readers. The area I will be talking about today is the part of the reader which makes a physical connection to either give write access or provide write protection. It’s the thin metal strip the blue arrow is pointing to.
What gives the SD card write protect error is when that metal strip does not make contact with another metal strip on the inside of the card reader. When the SD flash memory card is pushed inside the card reader, the internal metal strip is pushed outward and makes contact with the outer metal strip shown in the picture above.
To give you a better idea, here is a rough drawing / schematic of the metal connectors:
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