NRF52840 QSPI Quad mode pins to avoid via-in-pad.

[rgujju]

Hello,

I am routing the NRF52840-QIAA chip and wanted to avoid the costly via-in-pad process.

Can I use the following pins for QSPI quad mode?

Also can i leave the RESET pin (P0.18) floating or do i need to have an external pull up?

[ovrebekk]

Hi

What frequency are you planning to run the QSPI interface at?

The QSPI has only been tested with a set of specific pins, as detailed in the pin out in the product specification. 
Using it at other pins might have a negative effect on chip performance, and could affect things such as receiver sensitivity. 

Also can i leave the RESET pin (P0.18) floating or do i need to have an external pull up?

Are you planning to configure P0.18 for pin reset?

There is an internal pullup on the pin, so you don't need to use an external pullup to use it for pin reset. 

Best regards
Torbjørn

[rgujju]

ovrebekk said:

What frequency are you planning to run the QSPI interface at?

16-32 MHz.

[ovrebekk]

Ok, thanks. 

I will have to check with the test team if we have any additional testing data available. I will try to get back to you on this early next week. 

Best regards
Torbjørn

[ovrebekk]

Hi 

Unfortunately the people that can help with this is still not back from summer holiday. They should be getting back next week, and I will do my best to get you an answer by then. 

Best regards
Torbjørn

[ovrebekk]

Hi again

Apparently these pins should work fine if you limit the frequency to 16MHz or less, and keep the connections between the chip and the external device short. 

Feel free to share your layout with us when you have designed it, and we can look it over to make sure it looks fine.
(please open a new devzone ticket for this)

Best regards
Torbjørn