help: programming the FLASH excess the physical memory size

[tcheung]

Posted on October 13, 2015 at 21:12

the mcu i used : STM32F105R8T6, the flash size is 64k, according to the PM0075, the last page should be 0x0800 F800 ~ 0x0800 FFFF. However I tried to write and read back the data on page 0x0802 0000 ~ 0x0802 07FFF , and page 0x0803 F800 ~ 0x0803 FFFF, it still works ! ( I did recycle the power to make sure the data has been saved on FLASH then did the read back operation)

Can anyone help me to explain this ? many thanks!

[Tesla DeLorean]

Posted on October 14, 2015 at 01:14

You read it with the debugger, or via the MCU itself?

It is common to have a single die, and only test a portion of the FLASH memory, and mark it at the lower capacity. The 205 parts have 1MB, even the 256KB ones, it would cost 4x as much in tester time to test it fully.Not familiar with the STM32F105R8T6, you should be able to read via an incrementing pointer starting at 0x08000000 until the read Hard Faults, to determine the actual size. I'd expect the SRAM to also be bigger, and you could read that from 0x20000000