Bootloader & flasher for QPI external flash

[willemml]

Need to finish QSPI flash and then create a boot loader so RustWorks can be flashed to external flash.
Potentially useful links:

• flashAlgorithm docs: https://www.keil.com/pack/doc/CMSIS/Pack/html/flashAlgorithm.html
• flashAlgorithm for RP2040: https://github.com/rp-rs/flash-algo

Todo:

• Read external flash
• Write external flash
• Flash algorithm implementation so that cargo flash can access external flash (done in willemml/rsworks-flash-algo)
• Make probe-rs and cargo-embed use flash algorithm
• Enable writing external flash using dfu-util

[willemml]

As of ab41166 reading external flash seems to work correctly, but writing to it and erasing it does not. Unsetting memory mapped mode no longer causes a crash.

[willemml]

Note that external flash is actually supposed to be read as 32 bit integers, not individual bytes. This is shown (working) in a3d80ab.

[rfuest]

One issue I noticed in external_flash.rs is that you use self.qspi.cr.write instead of modify in send_command_full, which will some settings to their reset value.

[willemml]

Hmm, I tried using modify instead of write for cr but now attempts to write memory cause the calculator to either crash or freeze (without reseting, so I am going to assume it is waiting for the abort).

[willemml]

For reference, here are the changes I made:

self.qspi.cr.write(|w| w.abort().set_bit());

to

self.qspi.cr.modify(|_, w| w.abort().set_bit());

and then I also tried

self.qspi.cr.write(|r, w| unsafe { w.bits(r.bits()) }.abort().set_bit());

[willemml]

Thanks to #8 all that is left is to create a bootloader that also allows flashing of the QPI external flash via tools such as probe-rs and dfu-util.

[willemml]

There is a boot loader project called loadstone that looks interesting and is probably worth exploring...

EDIT:
Might be worth waiting for loadstone to directly use embedded-hal to make porting it to stm32f730 easier if the loadstone route is taken.
Will continue to explore alternative methods of using external flash for main program storage.

[willemml]

Flash algo attempt (fixed by rfuest in nw-rs/flash-algo#1): https://github.com/willemml/rsworks-flash-algo

[naveenprasathc]

Do you still have the issue?
I have worked on QSPI flash drivers, I can help if needed.