Wake up from Power Saving Mode by Timer Interrupt

The STM32H743 Chip has a quite high power dissipation.
As I understand the docs it is actually not supported to wake up the board through a timer interrupt.
Is it intended to include this function in future?

Did you try gpio wakeup for now and see if that works for you?

I can try gpio wakeup.
I don’t really have an actual application that needs to reduce power consumption but on my SC20260 board the MCU gets rather hot (can not bear to put my finger on it for longer than 3 sec).
So I thought it would be a useful feature to reduce power dissipation.
Btw: In the meantime I compared the temperature with the SC20100 board where MCU is much cooler. Is that normal? Perhaps there is something more wrong with my SC20260 board (the board where built-in ethernet didn’t work).

That is not normal.

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Not normal at all. Did you have ethernet issues or it was someone else? You have a bad module sadly. These parts were rushed out without full quality control.

Yes it was me where built-in ethernet didn’t work.
I now have tried hybernation mode --> MCU is only slightly warm, then I wake it up —> MCU gets hot. Except of ethernet and being hot the module works normally.

Are you in the US?

No, Germany. I can wait until they are available at Mouser.

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Finally I removed the faulty Ethernet PHY from the module, the board still runs fine and the MCU doesn’t get hot any more :smiley:


I don’t believe it. I need a photo :wink:

Yes, I must say that I was a little bit excited when I repowered it after the operation


Well done, so for extra points re populate it with a new phy. :grin:
Now give it a bath in IPA or a ultrasonic cleaner!


Lol, the board gave ‘informed consent’ to amputation, not transplantation.


OMG! you did!

Clean it with IPA.

What did you use to get it off the board?

I hope that Gus will not get an heart attack if I reveal my techniques.
First I replaced the 50 MHz oscillator (that’s where the damages in the suburbs are from) but it didn’t solve the problem.
Then I tried to heat the intact PHY chip from the surface with my big 75 W soldering iron but the solder didn’t melt.
Then I scratched off the ceramics like material from the chip with the edge of a iron saw blade and a cutter knife until I ended on a base copper plate. That was where the soldering pads lost their connection. Now I could easily desolder the base copper plate. After careful visual inspection and removing of shortcuts the board (surprisingly ?) worked fine.

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OMG :joy: I wish you took a video of that

Just FYI, if you have never seen this stuff, it works great for small SMD packages. I actually used it last night to pull an entire G120E SoM off a board. Good to have in your arsenal if you don’t have a rework station.


Thanks for the information. I never had to remove a chip before. In the meantime I watched some videos showing a hot air rework station.
It’s fascinating to see how this can be done.

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