# Uninterruptable power supply with Navigator

**URL:** <https://discuss.bluerobotics.com/t/uninterruptable-power-supply-with-navigator/15232>\
**Category:** Blue Robotics Software\
**Tags:** ardusub, navigator\
**Created:** [October 10, 2023, 12:45am UTC](https://discuss.bluerobotics.com/t/uninterruptable-power-supply-with-navigator/15232 "2023-10-10T00:45:21Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![Lewis\_Miles](https://avatars.discourse-cdn.com/v4/letter/l/ecd19e/32.png) [@Lewis\_Miles](https://discuss.bluerobotics.com/u/Lewis_Miles)\
**Post date:** [October 10, 2023, 12:45am UTC](https://discuss.bluerobotics.com/t/uninterruptable-power-supply-with-navigator/15232/1 "2023-10-10T00:45:21Z")

</div>

Hi All,

I am looking to integrate the [PiJuice](https://pinout.xyz/pinout/pijuice) Hat uninterruptable power supply into our ROV running the Rpi + Navigator.

I am having issues getting the autopilot software to run when the UPS hat is attached. Looking at the autopilot process it is outputting ‘runtimerror: Cannot fetch vehicle info as there’s not board running’

 ![Screenshot 2023-10-10 114224](https://us1.discourse-cdn.com/flex019/uploads/bluerobotics/original/2X/e/e596b3e890bcab0d9b458587ddb7a6a681bb68f7.png).

I am unsure how the hat would be causing this as it only connects to the power and GPIO 2 & 3 on the i2c lines.

I am wondering if anyone has seen similar issues with a UPS or has any guidance on what might be causing this issue.

Cheers,

Lewis

---

<div class="post-metadata">

**Author:** ![EliotBR](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/eliotbr/32/6937_2.png) [@EliotBR](https://discuss.bluerobotics.com/u/EliotBR)\
**Post date:** [October 24, 2023, 12:22pm UTC](https://discuss.bluerobotics.com/t/uninterruptable-power-supply-with-navigator/15232/2 "2023-10-24T12:22:16Z")

</div>

Hi @Lewis_Miles,

> [@Lewis\_Miles](#):
>
> I am unsure how the hat would be causing this as it only connects to the power and GPIO 2 & 3 on the i2c lines.

The [Navigator](https://bluerobotics.com/store/comm-control-power/control/navigator/) uses GPIO pins 2 and 3 as the internal [I2C-1 line for some of its sensors](https://github.com/bluerobotics/navigator), so it’s possible there’s an access conflict between the autopilot and the UPS functionality, and/or an address conflict with one of the sensors.

There may also be a conflict between the Navigator and PiJuice boards’ EEPROMs, and/or the hardware (device tree) overlays they define.

---

<div class="post-metadata">

**Author:** ![RaulTrombin](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/raultrombin/32/11853_2.png) [@RaulTrombin](https://discuss.bluerobotics.com/u/RaulTrombin)\
**Post date:** [November 1, 2023, 10:54pm UTC](https://discuss.bluerobotics.com/t/uninterruptable-power-supply-with-navigator/15232/3 "2023-11-01T22:54:30Z")

</div>

Hi @Lewis_Miles,

Could you please provide the following informations?

Are you running BlueOS?  
Have you tried running the system without the PiJuice HAT? If so, does it work fine?

If it does, it seems like the issue might be related to an overlay setup made in your PiJuice EEPROM. Apparently, you can disable or remap it.

First, I would suggest installing the `i2c-tools` and checking if the navigator I2C devices are functioning correctly. Please run the following commands:

```auto
pi@blueos:~ $ sudo apt-get install i2c-tools
pi@blueos:~ $ i2cdetect -y 1
00: -- -- -- -- 0C -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- 48 -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- 76 --
pi@blueos:~ $ i2cdetect -y 4
00: -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: 40 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: 70 -- -- -- -- -- -- --

```