Custom board using a STM32H735IGK6 based on a STM32H735G-DK dev board. Different format processor and a different external flash memory (MX66LM1G45G) due to lack of availability of parts. I need an external flash loader. Can I get one or how do I create?

[Tesla DeLorean]

ST has documentation, videos and examples. It's relatively complex, and they are hard to debug.

Start by developing BSP code that can read, erase, and write from application space. Debug it there, but comfortable that the hardware works and is functional.

You used the same pins as the H735G-DK, or some other combination?

Not seen much interest/activity in many months. Can ZIF mount the BGA's but not in OCTO configurations, really need guinea pigs..

https://github.com/cturvey/stm32extldr/tree/main/h7_mx66lm1g45g

Had the prior models working

https://github.com/cturvey/stm32extldr/tree/main/h7_mx25lm51245g

[PDixo.1]

24-BALL BGA (5x5 ball array) on custom board

[PDixo.1]

I believe I have managed to create a new external loader (using the IAR IDE) based on the MX25LM51245G loader code (from https://github.com/STMicroelectronics/stm32-external-loader) and have changed the Dev_inf file to reflect the change in memory size to the MX66LM1G45G flash. Looking at the datasheets for both chips they look virtually identical on commands and timings. I still dont appear to be able to either reliably communicate with the MX66LM1G45G chip and can't reliably erase, read or program. Any guidance as to what parameters I should be changing?