Does anybody know of a Windows app that allows erasing as opposed to overwriting or wiping? I could build an Arduino SD card eraser, but would rather find a Windows app that does the same thing - mainly because I think the SDFAT example doesn't go beyond SDHC. I just want the card's controller to recognize the memory as being in the erased state. I want the flash memory to be literally erased, and I don't care if the previous data might somehow be recoverable by the NSA. They talk about "secure erasing" or "wiping", and what they really mean is overwriting the entire card with ones, zeroes or random data, even multiple times. But everything I see for "erasing" an SD card in Windows uses the word in a different way. In fact, in the SDFAT library for Arduino, there is an example called SDFormatter.ino which purports to do exactly that, and the source shows that CMD38 is indeed called. So it appears to be possible to erase a card back to its factory state. Looking through the standard SD card commands, I see CMD38, which supposedly erases a sector or group of sectors. Presumably such a card is in the erased state other than the areas used to set up FAT32 or other file system. This idea is supported by my understanding that in testing an SD card's performance, testers use a card which is fresh from the factory, and not previously used. Erasing a card might make data logging easier because writes would be faster. I have the idea, from somewhere, that the SD card controller keeps track of which sectors are already erased, and therefore don't have to be erased before writing data to them.
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