RE: how can I allocate array in flash

Raoul — Thu, 26 Jan 2023 06:59:15 GMT

Hi Hadar,

If I understand you correctly you want to pre-set some i2c communication parameter in flash and so you want to allocate space for an array, at compile time, to a specific absolute memory address. Is that right? Could I ask why you want it stored to a specific address?

Doing this at compile time would be similar to what someone tried to do in this case: nRF Connect SDK -place variable in flash at predefined location

What you would have to do is use GCC attributes to place your array in a specific linker section, and then create a linker script to place that section at a certain address. I'm not very familiar with this but if you want some more details on the process you could take a look at this article, or this answer on Stack Overflow, with a minimal working example.

To do this within Zephyr's build system, you would need some Kconfig options allowing the use of custom linker scripts:

CONFIG_HAVE_CUSTOM_LINKER_SCRIPT=y
CONFIG_CUSTOM_LINKER_SCRIPT="custom_linker_script.ld"

Please look at Zephyr's code relocation sample (where I found the kconfig options above) and the documentation page on code and data relocation. Although, what you're doing is a bit different, you're only "moving" a single array instead of everything.

If you want to store the communication parameters to flash at runtime, (like this customer: "storage_partition" status after firmware Update ) then you can use the NVS API, see this sample: https://developer.nordicsemi.com/nRF_Connect_SDK/doc/latest/zephyr/samples/subsys/nvs/README.html

Best regards,

Raoul