Preferred Method to Read Images from Non Addressable External Memory

[kengineer]

I'm wondering what the preferred method would be for reading images off of non addressable external memory (i.e. a SPI Flash). Obviously this isn't difficult if we are running something like FATFS on the external medium as this integrates perfectly with the GFILE module - but if we're not, what is the best method to do this? Also, this is a low performance system, so I don't have huge amounts of RAM that I can use to cache images.

[inmarket]

The easiest way is to write a GFILE interface for your SPI Flash. GFILE interfaces are pretty simple.

You don't even have to support a full file directory if you are using the entire SPI Flash to hold a single file - just hard code a filename match against say "SPIFlash".

As the flash is non-addressable you will need to reserve some RAM as a "block buffer". I would suggest going no lower than about 8 bytes for that buffer. Obviously the larger the RAM buffer the faster image rendering is likely to be because more of the image will be in RAM at any point in time.