Backup PWR to DUE's RTC

I am looking for a way to isolate the VDDBU pin 52 and connect to a Li Battery so the built-in RTC will maintain time.
Pin 52 is connected to 3V3 as per the schematic. I looked at the board with a magnifier and the clad goes to a plate thru.
I was wondering if the pin can be isolated by drilling out the plate thru.
Has anyone attempted to attach an Li successfully?

On second though, I am reconsidering doing any physical changes to the DUE.
I am looking at attaching an external RTC with Li Bkup support.
I'll update when complete.

Planning to build a shield to plug-in to the DUE and connect to the SPI interface and a digital pin for Chip Select (CS).
I have a DS3234 module with an Li (CR1220) Backup (not Dead On RTC but a cheaper Asian version) that will maintain the Date/time.
I am looking at options of updating the DUE bootstrap vs. loading the code to set the built-in RTC with every new sketch.
Any suggestions form past experiences?

For any one trying to use the RTC, I've made some notes than should get you started (see attached).
I have replace the docx file with a pdf.

RTC Setup.pdf (87.9 KB)

I could not open that docx file, and don't trust them anyway. Any chance of a PDF?

Do you plan to publish a library for the DS3234?


Rob

Rob,
I've just started on the DS3234 and yes, I post what I have in a couple of weeks.

Thanks.


Rob