Hello. Thoughts on using the crazy idea of using a write protected micro SD with Diet Pi on a Pi A+ for a standalone music player?
I published plans (DQMusicBox) for a simple music player for people with dementia. I’d like to make it more resistant to unexpected loss of mains/power. I quite like DietPi for that. I’m thinking of taking it a step further and using hardware write protection on the micro SD card. More specifically, setting the TMP_WRITE_PROTECT bit on card’s CSD (Card Specific Data).
I did a quick test of this. Superficially, it seems to work. That is, DietPi boots and I can play music. However, it works in an interesting way. The micro SD still accepts write requests, but it never actually writes anything.
If I were to do this, I would use a tiny writeable USB memory stick to store the music. I recognize that this would make it more difficult to update the device. Note that the device is intended to be standalone i.e. generally not on a network.
Using hardware write protection is a pretty big hammer. And I would lose a lot of capability. But perhaps I would still have the capabilities that the device needs.
Note that the write protection mechanism above is not the old-style slider switch on big SD cards, rather it’s a bit setting on the card itself. Thus it can be enabled and disabled in software. A few links about this: