CC2564C: Part is not resetting correctly

Lauren Mayfield

Part Number: CC2564C

We’re seeing an issue where the TI CC2564C part won’t reset correctly by simply pulling nSHUTD low (tested with over 100ms held low). We’re following the guidelines in sec 5.8.1 in the datasheet. We’re running both VDD_IN and VDD_IO are running from the same 1.8V rail.

What we’re seeing is that the RTS signal is not behaving as expected. I’ve included shots showing the initial power on which shows RTS pulse low when BT nSHUTD goes high (approx. 1.5s after the trigger). The other shot shows what happens if nSHUTD is held low and then released while the 1.8V rail is still applied. We see RTS puls low, but then it does some toggle and stops high.

Any ideas what might be going on? Have you seen this behavior before?

over 5 years ago

0 Lauren Mayfield over 5 years ago

TI__Expert 7915 points

Please contact me internally (Lauren Baker) for the schematics. Thanks.

0 Alexis Crandall20 over 5 years ago in reply to Lauren Mayfield

TI__Genius 15590 points

Hi Lauren,

Sorry for the late response here. I have received your schematic and will provide feedback early next week.

Thanks,

Alexis

0 Lauren Mayfield over 5 years ago in reply to Alexis Crandall20

TI__Expert 7915 points

Hi Alexis,

Any update?

Thanks,

Lauren

0 Alexis Crandall20 over 5 years ago in reply to Lauren Mayfield

TI__Genius 15590 points

Hi Lauren,

I need more time to look into the schematic. In the meantime, can you verify that the nSHUTDOWN and HCI pins are interfaced as 1.8V? from your scope capture it looks higher...

Thanks,

Alexis

0 Lauren Mayfield over 5 years ago in reply to Alexis Crandall20

TI__Expert 7915 points

"We are running BT at 1.8V. One of our designs has the main GPIO VDD at 3.3V, but we use level shifters in that design to interface at 1.8V to BT."

0 Alexis Crandall20 over 5 years ago in reply to Lauren Mayfield

TI__Genius 15590 points

Hi Lauren,

I don't see level shifters in the schematic. It looks like the RESET_BT, and all of the HCI nets go directly between the two devices without level shifting.

Thanks,

Alexis

0 Lauren Mayfield over 5 years ago in reply to Alexis Crandall20

TI__Expert 7915 points

There are 2 designs with the same BT not resetting properly issue. One design uses the level shifters, one design doesn’t. The schematic I sent you is the one that does not.

0 Alexis Crandall20 over 5 years ago in reply to Lauren Mayfield

TI__Genius 15590 points

Hi Lauren,

In the design you sent, if there is no voltage translation being done and they are not operating at 1.8V, I believe this is your issue. you may be damaging the part.

For the design that uses level shifters, can you provide the part number for the level shifters you are using?

Thanks,

Alexis

0 Lauren Mayfield over 5 years ago in reply to Alexis Crandall20

TI__Expert 7915 points

Hi Alexis, just sent that to you internally.

Thanks,
Lauren

0 Lauren Mayfield over 5 years ago in reply to Lauren Mayfield

TI__Expert 7915 points

One design uses GPIO VDD of 1.8V and uses no level translators. The other design uses GPIO VDD of 3.3V and uses level shifters to 1.8V on all BT GPIO (UART, nSHUTD, etc).

0 Lauren Mayfield over 5 years ago in reply to Lauren Mayfield

TI__Expert 7915 points

Any update on feedback?

0 Alexis Crandall20 over 5 years ago in reply to Lauren Mayfield

TI__Genius 15590 points

Hi Lauren,

Since we have taken this discussion offline, I am going to close this thread and continue support via email. It makes it easier to keep the discussion in one place.

Thanks,

Alexis

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CC2564C: Part is not resetting correctly