We’re facing with a problem with clock on the Jetson Xavier. Every time we power off the device, its system time after rebooting becomes somewhere around 2000-01-01 23:12:49. No internet syncronization (like ntp) is possible, so I believe the issue is critical. I started digging and found out that…

@jetsonxvr when Xavier is powered off, supercap stops charging regardless of power supply plug-in state. As per your previous experiment, when power supply is kept plugged after power off, the supercap voltage after an hour is 2.62V which is normal and expected. But when power supply is plugged out,…

Hello. I’ve done modifying and replacing of the .dtb file successfully. After that, I rebooted Jetson and checked if the changes are there by command: $ dtc -I fs -O dts /sys/firmware/devicetree/base …and I see there backup-battery { backup-battery-output-resister = <0x64>; status = "oka…

Could you confirm /proc/device-tree are the same with /sys/firmware/devicetree/base Also could you probe to make sure the voltage is corect. sudo dtc -I fs -O dts /proc/device-tree

Also you may need to program the pmic REG as below. Low-Power Mode (PWR_MD_32K[1:0] = 0b00)

Hello there, ShaneCCC, thak you in advance for the response. I checked the /proc/device-tree and it says: status = "okay" Where should I probe the voltage and what shold it be? 0x64 means 100, so… 1V? Sorry, again, I didn’t quite get it, where can pmic REG be programmed? lAgain, I appreciate yo…

supercap should work by default. Are you setting the time and date after boot and then how long you are unplugging the power supply before you plug in again?

Hello bbasu, Supercap is definetely not working. Yes, I do set the time after boot and then after, say, 2-4h of unplugging I plug it again and the time is in January, 2018. Device tree modifications are also not working.

Hi, How long you have charged? And can you charge for an hr and then do the test for 5 minutes of unplugging to see if rtc is keeping the data? Meanwhile checking locally about the exact time and capacity of supercap. thanks Bibek

Hello, I tested with the following: Worked for many hours on jetson Left Jetson powered off but plugged in for an hour Unplugged Jetson for 5 minutes Plugged Jetson in and checked if time persists. The answer is: no, Before unplugging: Local time: 2020-04-16 15:39:21 MSK Universal time: 2020-0…

@ShaneCCC @Bibek , bubbling this up to get an answer, thank you!

Supercap is not working

Robotics & Edge Computing Jetson Systems Jetson AGX Xavier

rkasirajan April 20, 2020, 10:22am 19

Hi,
Please check the voltage of supercap across its terminals using Mutli-meter. After an hour charging, voltage should be close to 3V. The supercap can be located near 40-pin connector. You can refer attached picture to find +ve and -ve terminals of supercap.

Supercapacitor shows 0V even when powered on

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Supercap is not working

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