Lidar Lite v3 HP not detected on Pixhawk 4

ArduCopter Copter 4.0
1

I am some trouble getting Copter 4.0.3 to recognize the lidar lite v3 HP that is installed on the copter I am working on.

I get the following message in mission planner: PreArm: Rangefinder 1 was not detected

Here are the parameters I have the Lidar set up with.

image
image2880×1800 525 KB

There is also an IR LOCK on the same I2C bus that appears to be recognized.

When I put my phone’s camera under the Lidar lite, I don’t see a blast of IR light from an LED or laser, so I am not sure if the unit is getting power or not (I will check this with a voltmeter shortly)

2

Lidar is getting power. Measures out to 4.88V.

4

@Matt_C

It’s powered from the internal 5V rails on the PH4. We’re doing up a wire harness to fix that right now, as we suspected that was part of the problem.

5

update: harness changed to support power from external source. The unit is getting 5.24V now. No change to behavior.

6

note: I am using I2C for the interface.

8

Phone cameras sometimes don’t have IR filters on them which makes checking if the lidar is on easier. I had an issue with the 1 kOhm resistor. I ended up using a 660 resistor.

9
  • it’s on an I2C splitter (the I2C line going back to the Pixhawk 4 has GND/SDA/SCL only, I removed the +5V pin from the connector)
  • Power is from a dedicated that powers only the lidar lite and an IR LOCK camera
  • If I remove the IR LOCK camera I observe no change in behavior
  • I checked the wiring harness for SCL to SDA crosses and did not find any issues
  • with the lidar only the I2C bus has no traffic between pixhawk 4 and lidar

I looked at the lidar with my phone camera and didn’t see any evidence of the IR light source running, so it’s not clear the unit is powered up.

10

We got a spare regular Lidar Lite 3 (not the HP) and swapped that into the system and it appears to work, so it looks like we had a dead lidar on our hands… We’re gonna put the setup back together and test the whole system and see if we get the IR LOCK to work.

1 Like
11

Oddly enough, the IR LOCK and the LIDAR can’t share the same I2C bus, which is annoying.