STM32F746G-DOSCO, FLASH

[AD�?b]

Hello

I want to write to FLASH variable uint32_t time at power off. Which signal to use for this?

greetings

Andrzej

[Tesla DeLorean]

What signal? There isn't one telling you the power source is collapsing. You could perhaps use an EXTI to an external trigger circuit, but you'd need to be able to keep the system running long enough to do whatever you need. Perhaps it could switch to the reserve supply, and then go directly into STANDBY until the primary supply is restored.

The flash is relatively slow, and uses a charge pump, it is generally inadvisable to try and write with a failing supply. You might consider writing to BKPRAM, and powering the VBAT from a battery or super-cap. You could perhaps update this in the 1 KHz task.

[AD�?b]

Hi

I have to save only one uint32_t variable after power off.

Can't use PWD signal and EXTI 16 interrupt?

What do you think?

greetings

Andrzej

[Clive1 (HNL)]

Yes, EXTI 16 would generate an interrupt. Not sure it gives you time to write to flash, or if that's a desirable course of action.

You'll need to weigh the risks there.

The flash sectors are quite large, and slow to erase, you'd want to journal your 32-bit write across a sector so the time to write is short.