I'm trying to come up with a simple method for users to update the firmware on my UC3A3 device. I already have a "Mass Storage Class" mode, which enables a read/write interface to a SD Card (it works exactly like an Android phone's ability to have a host computer mount the SD card). When my device boots it scans the SD card for required files, so I'm thinking the obvious answer is to have the user copy the firmware to the SD card, and then if the device detects "upgrade.hex" it will automatically flash and reboot. Has anyone else done something like this? I know it's possible, just wondering if there's anything existing that I can build off of before I go start from scratch.
Additionally, when providing this type of functionality, I think it makes sense to make some sort of signed images to ensure you don't overwrite your flash with garbage. My first thought is just an md5sum since that's relatively easy, but I'm open to suggestions if anyone has better ideas.