# GPS & IMU into VOXL2 (outside of dsp)

Source: https://forum.modalai.com/topic/1323/gps-imu-into-voxl2-outside-of-dsp
Category: VOXL 2 and VOXL 2 Mini (https://forum.modalai.com/category/26/voxl-2-and-voxl-2-mini)
Tags: voxl-2
Posted: 2022-09-13 15:05:03 UTC by ryan.langlois1
Replies: 6 · Views: 1336

## ryan.langlois1 · 2022-09-13 15:05:03 UTC

We're looking to pull in GPS and IMU data into the VOXL2. We are not using the DSP. We are using an external flight controller with the VOXL2 as a standalone SBC for our autonomy. We want to use an external IMU and Compass to improve our state estimation. What would be your recommendations on doing this?

## Reply by Eric Katzfey (ModalAI staff) · 2022-09-13 15:51:24 UTC

@ryan-langlois1 How are you connecting your external flight controller to VOXL 2? For the external IMU and compass, which units were you considering using? There are 2 IMUs on the VOXL 2 board as well, would you rather use one of those?

## Reply by modaltb (ModalAI staff) · 2022-09-13 15:55:33 UTC

Hi @ryan-langlois1 ,

Also, check out [this](https://docs.modalai.com/voxl2-external-flight-controller/), we have a few options to expose an apps_proc UART and then we can pump MAVLink through it between the two systems.

This is a use case we are internally using presently, but it's not in the production release just yet (it's in the dev branch of `voxl-mavlink-server` https://gitlab.com/voxl-public/voxl-sdk/services/voxl-mavlink-server/-/tree/dev)

## Reply by ryan.langlois1 · 2022-09-13 16:48:36 UTC (in reply to Eric Katzfey)

@Eric-Katzfey We're using a daughter board; yours (the 3.0 with UART & USB) and we have a custom one that essentially does the same as yours, but we're converting USB to ethernet on-board. This eliminates our need for a fat external USB to eth converter. As for external IMU, we're considering a vectornav VN200. We currently fly that same unit on a different airframe. We are also considering using the ones onboard the VOXL2, but I'm assuming it's a low cost "hobby-grade" mems? I believe it's the icm-42688 so I'm looking at it online and comparing to the vectornav units.

## Reply by ryan.langlois1 · 2022-09-13 16:52:25 UTC (in reply to modaltb)

@modaltb thanks for the info, but we already have our UART configuration working. See my response to Eric Katzfey for explanation. We're about to start doing some gps-denied research in-which we expect to have gps, and then have gps get jammed. We'll need a better IMU than the mems on pixhawk and VOXL2. 

For what it's worth, we're starting small here. GPS-denied SLAM is not our wheelhouse. We develop fully autonomous "plays" and swarming algorithms on fixed-wing UAS.

## Reply by Eric Katzfey (ModalAI staff) · 2022-09-13 16:59:35 UTC (in reply to ryan.langlois1)

@ryan-langlois1 said in [GPS & IMU into VOXL2 \(outside of dsp\)](/post/6237):
> vectornav VN200

Yes, we have a couple of the 42688 on board. What are the external interfaces on the Vectornav unit?

## Reply by ryan.langlois1 · 2022-09-13 17:24:38 UTC (in reply to Eric Katzfey)

@Eric-Katzfey 232. I'm not terribly worried about it. I've worked with their VN-100 series before, which we might go with. A logic shifter should work fine. So maybe we open another UART? Our custom daughter board connects to J3 and J5 so we can get more than 1 UART even though we're currently only using UART7? from the J3.