STM32MP13x PDR_ON floating - random boot issue?

[rubensch]

Hi,

we have a custom design with an STM32MP13xx CPU.

We currently see random issues during boot. Some of the prototypes randomly stuck on boot without any output on the serial console, sometimes they are booting well. When a board has booted it runs stable without any issues.

In error case, the oscillator does not start, we don't see any i2c communication to the PMIC and also the RAM power supply is not there.

After review of the layout we saw that PDR_ON is floating and not connected to VDD as required in the datasheet and AN5474 (Getting started with STM32MP13x lines hardware development).

My question:

- can a floating PDR_ON pin lead to this random boot issues?

- what else can be checked or is required if the oscillator does randomly not start running?

Thanks in advance and best regards

Ruben

[STOne-32]

Hi @rubensch ,

Yes, having that pin critical pin floating can create such issues of boot, running with PDR Off depending on your external power ramp on or off and can be used only when you have a special Power supply that can not go beyond a specific value as stated in Datasheet. Can you please connect it and let us know how many parts / times are not working before  we after .

Hope it helps ,

STOne-32

[rubensch]

Hi @STOne-32 ,

sorry, I didn't fully understand your answer.

We will connect the pin to VDD in our next prototype. For now, we are searching for ways to ensure that this change will fix the reboot issue and that there is no other problem.

Are there any ways to come around the boot problems caused by PDR_ON in Software? By flashing some OTP or something else?

Thanks for the quick response!

Ruben

[rubensch]

@STOne-32 or the more concrete question: Will the oscillator not start if PDR_ON is connected to VSS?

[Olivier GALLIEN]

Hi @rubensch 

I confirm that PDR_ON might be connected to VDD.

If connected to VSS, MP13 will not boot. 

This is stated in errata : 

STM32MP131x/3x/5x device errata - Errata sheet

System 2.2.4 Boot issue when PDR_ON pin is set to VSS 

Olivier 

[rubensch · Accepted solution]

Hi all,

we finally managed to connect the pin on our current board version by removing a part of the housing and put a wire on (real frankenstein wiring). With PDR_ON connected to VDD the issue is gone. We will add this to our next HW revision and hopefully have this issue finally resolved.

Thanks for your input

Best regards

Ruben

[STOne-32]

Hi @rubensch ,

Thank you for the follow-up and glad to see your design is fixed.

Ciao

STOne-32.