VNF1048F device is in LOCKED state always

[krishnaduriseti]

Hello Team,

I have some problem with unlocking the VNF1048F chip using SPI communication, I have the got the read working but chip is always in LOCKED state and when I try to unlock according the sequence mentioned in datasheet doesn't work.

I try to set UNLOCK BIT , WD_TIME and WD_TRIG bits in CR3 and in the next step

I try to set EN bit in CR1

But when iIread back these registers, values are 0 always and status register (0x11) shows LOCKEDM is 1 WD_FAIL is 1. To be able to set WD_TIME and WD_TRIG bits should I unlock the device first?  Not sure what is the startup sequence.

Could you please share the initial configuration of the chip or any example code would be greatly appreciated.

Thank you in advance !!

Regards,

Krishna duriseti.

[krishnaduriseti]

Hello Team,

Do you have any feedback for my post. As this is bit critical for our Project, Any feedback is greatly appreciated.

Thank you so much and looking forward for your feedback,

Regards,

Krishna.

[rnvarsha]

Hi,

Did you get this issue resolved? Or do you have any working example code implementation for Vnf1048 which I can take as a reference. Please share if you have any.

Regards,

Varsha

[krishnaduriseti]

Hello,

Yes my issue is resolved.

First we have to reset the chip and then unlock on startup. T

Then in the main loop I continuously write UNLOCK bit 1 in CR3 and also refresh watchdog for every 50ms. And I have set my WD window as 200 ms.

Above steps solves my problem and chip OUTCTL feature works for my application.

Hope this helps.

Regards,

Krishna.

[rnvarsha]

Hi @krishnaduriseti,

Thanks for your quick reply. Can you please explain why we need to continuously write UNLOCK bit 1 in CR3 in the main loop as this has not been mentioned in the datasheet provided by ST.

Regards,

Varsha

[krishnaduriseti]

Hello

I mean we need to continuously write EN bit 1 in CR1 according to datasheet, But I also write UNLOCK bit to 1 while refreshing the watchdog.

Regards,

Krishna.

[rnvarsha]

Hi,
As per the datasheet, we need to set this EN =1 whenever we need to send a GOToUnlocked sequence only, isn't it? Why do u need to set it continuously with watchdog. I want to know the reason actually why the device is going to locked state on its own even if I don't have the watchdog failure or SPIE error. What is making the EN bit go low?

Regards,

Varsha

[krishnaduriseti]

Hi,

I didn't really understand the reason why the device goes to locked state on its own, for me above sequence is working so I didn't really investigate the issue so much. And I agree with you datasheet is not very clear on what needs to be done to make the chip working.

Regards,

Krishna.