Prearm: Rangefinder 1 was not detected

u777777 · May 30, 2021, 8:37am

HI,there
I am trying to enable my lidarlite v3 connected with pixhawk4mini via i2c.
I set the parameters accroding to wiki https://ardupilot.org/copter/docs/common-rangefinder-lidarlite.html
I set RNGFND1_TYPE = 15
RNGFND_1_MAX_CM = 3500
RNGFND_1_MIN_CM = 20

But I get message on MP Prearm: Rangefinder 1 was not detected
and the sonarvalue is 0.

Here is my connection photo

Firmware in px4mini and MP is the latest version

Thanks!

Dave84 · May 31, 2021, 10:50am

Good day, you need customize you cable… add a 680uF cap to the power lines of the sensor… pin3 from the sensor is SDA and pin4 is SCA
Don’t exceed the 5.5 volts on the sensor

rickyg32 · May 31, 2021, 5:13pm

It should have it’s own bec and not powered from the flight controller.
I use to have that same problem with TF minis. Not anymore…they have their own juice now

u777777 · June 4, 2021, 8:11am

@rickyg32 Thanks for replying
So, I need to give lidar individual power supply instead of using power pin on flight controller.Just connect sda and scl Pin to flight controller?
like the photo below

I will use other cable to connect

rickyg32 · June 4, 2021, 11:37am

yes at least in my experience and that of a few others, the power needs to be separate. Only because the lidar pulls more then the FC can properly handle. Yes the SCL and SDA connect to the FC. My drones I use a 9am power module that feeds the FC and it’s tapped for other devices to keep the load of the fc. Weird things happen when the flight controller is not properly powered.
I think you have it.