Anybody using analog sonar on PH2.1?

Is anyone successfully using an analog Maxbotix sonar rangefinder on the PH2.1…specifically on the ADC port?

Currently maxbotix I2C units cannot be used on the 2nd I2C bus and I was not keen on cutting into my Here GPS cable, so I ordered the MB1240 analog unit and wired it for the ADC port per the instructions at

Using the params as instructed I saw no response in the sonar voltage. I tried changing the pin to 15 and manually adjusting the scaling. This resulted in accurate response from the unit but only up to approx 1.5m. I’m running Arduplane 3.7.1 and the most recent Mission Planner…although I temporarily flashed my PH2.1 with ArduCopter and had similar results.

I did separately test the sonar with a regulator and multi-meter to make sure it wasn’t faulty…seemed to be working fine.

I have analog sonars on legacy Pixhawks that work, which is why I’m asking this in the PH2 section rather than plane. Thanks!



I’m in the same boat. We just switched over to PH2.1 units and we’re trying to do the same thing with Maxbotix analog sensors and the ADC port.

Were you able to find any resolution?




We have not yet found a clean resolution. We tried using the analog MaxBotix units on the ADC port, but the power supply to that line was so noisy (on all the units we tried) that the sonar automatically decreased it’s usable range down to about 2m.

Right now we are considering moving to optical units, probably Lightware.

I did create a Git issue some time back and it looks like there’s been some motion there in the last day or two. I’m waiting to see if a clean fix happens.

If you come up with anything, please let me know!


Also in the same boat. Just switched to PH unit and cannot get the Maxbotix sensors to work on the ADC port. Have voltage at the Maxbotix and getting a variable voltage back based upon range from sensor. Have tried other sensors, a whole lot of different settings and getting same results, no data showing up in Mission Planner.




I’ll definitely let you guys know if we make progress on this issue. I can’t tackle it in the first half of June due to travel, but I’ll resurface again mid-June to revisit this issue.

One thing that could eliminate the ADC issue would be the ability to use multiple I2C Maxbotix sonars. Since we receive I2C splitter boards with our PH units, it would be significantly easier to implement these types of sonars. We always change the addresses on our Maxbotix I2C sensors, but Lightware’s I2C sensors are the only ones that can be individually addressed using unique I2C address. I’ll have to check to see if this is an existing feature request (we’re using the rover software).