How to install an RTC battery on the Jetson Orin Nano

[woz4tetra]

I’ve encountered the same problem with setting up the RTC on my Jetson Orin Nano:

How to add RTC battery in Jetson Orin Nano

Hello, this is my first post. I couldn’t find any information about how to add RTC (real time clock) battery holder for Orin Nano. Would you tell me how to add battery? The document says 'The connector used is a Wieson Technologies AC2651-0011-003-HH, 2-pin, 1.25 mm pitch connector’, but I couldn’t find it by googling. For Jetson Nano, this https://github.com/marshallmassengill/JetsonSuperCapRTC worked for me. But, Orin Nano’s surface looks different. I would be grateful if you could give me s…

Kinda crazy that there’s no connector or battery housing installed on the dev board.

I followed what I could. I found this document:

Jetson_Orin_Nano_DevKit_Carrier_Board_Specification_SP-11324-001_v1.1.pdf

It shows the location of J3 on page 6 and says pin 1 is power, pin 2 is ground on page 26. I assume the arrow is pin 1. I verified this by probing pin 2 and saw that it shares a ground with the rest of the chassis. Given this, I installed a CR1220 battery holder and ensured it was delivering at least +3 volts between pin 1 and 2. No dice. RTC kept resetting between power cycles. Then I realized I needed to install a resistor. I installed a 1K ohm resistor on a near by pair of tiny pads but have no idea if it’s the correct one. This also didn’t work so I assume not. I see R560 in the schematics but I can’t find any documentation saying where those pads are physically on the board.

Can anyone assist here? Since this feature is clearly lacking on this dev board, does anyone recommend a way to get an external RTC through I2C or something?

Thanks

[Trumany]

R560 position is as below showing. Basically you can find components position in P3768_A04_PCB_assembly_drawing.pdf in carrier board package: Jetson Orin Nano Developer Kit Carrier Board Reference Design Files

[woz4tetra]

Oh I see. I wasn’t sure what I was looking at. The rectangle you’ve highlighted is the resistor location. So it’s a little to the left of the J3 pads. I installed a 1K ohm resistor there and it still didn’t work. Does that mean R222 needs to be shorted? I see the diagram has a 0ohm / 0.05 ohm label on it.

Just curious. Why was this omitted from the dev board when all previous models have these components? or at least larger solder pads so they can be added.

[Trumany]

R222 is unnecessary if D4 is mounted. You need to check if RTC0 is used referring to this topic: About setting the RTC time

[woz4tetra]

I followed those instructions also. I modified my udev rules and verified that /dev/rtc is mapped to /dev/rtc0. This still didn’t work.

[woz4tetra]

I ended up just buying a different dev board. RTC works out of the box with this one.
https://www.mouser.com/ProductDetail/713-102110770

[rjon428355]

Hello, I managed to use the RTC in the Orin Nano successfully! It seems there was a mistake with the resistor you used. I utilized the 560mOhm resistor, ERJ-2BQJR56X, which was quite small and challenging to mount. However, it functions without any additional settings:)

Here’s the link for DigiKey: ERJ-2BQJR56X

I’ve also attached an image of the tiny resistor on the board. I would be grateful if I could assist you.