Write to Flash only 64Bit

[Martin42]

Hello,

Can I only write to the flash with 64 bit variables, or also 32/16/8 bit?
I just used this function for this: HAL_FLASH_Program(FLASH_TYPEPROGRAM_DOUBLEWORD, activepageaddress + u32_Offset, u64_Data)
I have an STM32L432 uC.

I already found this example: https://github.com/STMicroelectronics/STM32CubeL4/blob/master/Projects/NUCLEO-L4P5ZG/Examples/FLASH/FLASH_FastProgram/Src/main.c

Many thanks in advance.

[STTwo-32 · Accepted solution]

Hello @Martin42 

Flash programming is only by 64-bits at a time. On other series it can be 32-bits.

For more details refer to this post.

Best Reagrds.

STTwo-32

[Tesla DeLorean]

You'd use a structure (packed?) or array to consolidate the smaller variables into a larger / usable block that fits the minimum write width of the FLASH memory. You'd then write as a block.

[Martin42]

I would like to write a second firmware via Modbus and delete areas in the flash.
I send the raw HEX file using a PC tool and then write 64 bits at a time, since the flash only allows access with 64 bits.

To build the HEX file I use the addition "--gap-fill 0x00 --pad-to 0x08019000" to always get addresses with 32 bytes. This should also ensure that 64 bits are always written.
e.g. arm-atollic-eabi-objcopy.exe -O ihex --gap-fill 0x00 --pad-to 0x08019000 "${BuildArtifactFileBaseName}.elf" "${BuildArtifactFileBaseName}.hex"

-> Adds ":04018C00000000006F" the missing values for to fill 64 bit

:1001600059C0000859C0000859C00008000000002C
:1001700059C0000859C0000800000000000000003D
:0C01800059C0000859C0000859C0000810
:04018C00000000006F
:1001900010B5054C237833B9044B13B10448AFF3C1
:1001A00000800123237010BD1C010020000000000E

[Tesla DeLorean]

Not sure if there was a question there.

Either normalize the data on the host. Or as you process it on the target

[Martin42]

No question 🙂

I will do it on the target.