PWM in Stop2-Mode with LPTIM2

[JoachimO]

Hello,

I am using STM32U575 and would like toimplement a PWM output. This should also work in Stop2-Mode.

Clock for the LPTIM is LSE.

 

It works with LPTIM1 and 3 without any problems.

To generate a PWM in Stop2-mode, I use the LPBAM with LPDMA.

 

Now I would try it with LPTIM2, too. But it hasn`t work so far.

 

Is it even possible? LPTIM2 is connected to a different bus than the other LPTIMs.

The data sheet states that autonomous mode should be possible with LPTIM2?

 

Thank you in advance for your reply.

 

 

 

[Sarra.S]

Hello @JoachimO, welcome to ST Community

>>s it even possible? LPTIM2 is connected to a different bus than the other LPTIMs.

Indeed, in SRD, only LPTIM1, 3, and 4 are available: 

You can check the table of all the autonomous peripherals supported in stop2 mode in Getting started with LPBAM

[JoachimO]

 

Is there an error in the reference manual (RM0456, page 2465) or how is the line "Autonomous mode" to be understood?

 

[Sarra.S]

Hello @JoachimO, 

To be precise LPTIM2 is functional only in stop1 mode. As shown in the figure from AN5645

This is inline with the description in the RM: 

Sorry for the confusion! 

 

[JoachimO]

In the first table of your post, LPTIM1/2/4 are named for autonomous mode in Stop 2 mode.

Shouldn't that be LPTIM 1/3/4?

 

In the second table at LPTIM4 there is no autonomous mode available?

In relation to the table above, this would be a different statement.

[Sarra.S]

Thank you @JoachimO 

>>Shouldn't that be LPTIM 1/3/4? Indeed!

This typo should be corrected (Issue reported internally: Ticket 176652)