Non-volatile data storage in STM32F7 mcu?

[Abhishek Kumar]

Posted on November 21, 2017 at 14:04

I am using STM32F777II mcu where I wanted to know how to store non-volatile data? I see that this controller's datasheet doesn't say it has any EEPROM.

#eeprom #stm32-f7 #non-volatile #flash

[Tesla DeLorean]

Posted on November 21, 2017 at 15:11

There should be 4KB of BKPSRAM (NVRAM) powered by the battery attached to VBAT, this should be part of the PWR/RTC block.

http://www.st.com/content/ccc/resource/technical/document/datasheet/group3/8a/34/ed/7e/4c/04/4b/7a/DM00225424/files/DM00225424.pdf/jcr:content/translations/en.DM00225424.pdf

 

0x40024000 - 0x40024FFF BKPSRAM

Use a pointer to access, or create a structure for your data and use a pointer to the structure.

[Abhishek Kumar]

Posted on November 21, 2017 at 16:17

Isn't there any storage which does not needs external battery backup?

[waclawek.jan]

Posted on November 21, 2017 at 16:25

Yes, it is - the FLASH; but there are inconveniences related to using it as a backup memory (code execution from FLASH stalls, erase granularity is high, endurance limited).

JW

[Abhishek Kumar]

Posted on November 21, 2017 at 16:48

why these mcus don't have eeproms like the classic old mcus?

[Tesla DeLorean]

Posted on November 21, 2017 at 17:47

Because the size and process/geometry don't work well.

You can place small/cheap external components in the footprint of a 40pin DIP socket, along with the processor.

[Joerg Wagner]

Posted on November 21, 2017 at 23:59

I use FRAM, it's fast and very reliable.

For projects Flash will not be used very often, I shift my app to another address (i.e. 0x80020000)

to use the 32kB section(s). I believe in 100K erase operations under normal temperature conditions

and 10-20 years data retention, but nothing is forever...

[Tesla DeLorean]

Posted on November 22, 2017 at 01:23

How frequently is the data going to change? I tend to put user configuration data in FLASH, because it doesn't change all the time, and unlikely to change more than 100 times during the product life span. Things that don't change like MAC addresses, serial numbers or security keys could be written to OTP