AP_Rangefinder Lightware Lidar GRF 500 Driver Update Rate Parameter Set Improperly

[adpjhu]

Bug Report

Issue details

There is an error in the grf 500 datasheet that has caused the error in the driver. The datasheet contains the following statement: Writing this command will set the update rate in Hz. Adjustable from 0.5 Hz to 10 Hz in 0.1 Hz increments. and yet the value described is a float and stored in a uint32 format.

The GRF 500 interprets the update rate field not as hertz but deci-hertz. This has been confirmed by setting the RNGFNDx_GRF_RATE to 50 (its default) and using the Lightware studio software via serial passthrough to read back the value. In this case the value reads back as 5 hz instead of 50 hz.

Also the RNGFNDx_GRF_RATE parameter can not set the full range of values accepted by the update rate parameter for the GRF 500 as it cannot set values less than 1 hz. (minimum value supported is 0.5 hz)

It is likely the case that this field is interpreted differently for the GRF 250 vs GRF 500 as the grf 250 datasheet contains the following statement Writing this command will set the update rate in Hz. Adjustable from 1 Hz to 50 Hz in 1 Hz increments. I do not have a GRF 250 to test with so i cannot say for certain.

I will reach out to lightware support and post updates.

@rishabsingh3003

Version
latest

Platform
[ ] All
[ ] AntennaTracker
[x] Copter
[ ] Plane
[ ] Rover
[ ] Submarine

Airframe type
N /A

Hardware type
N/A

Logs
N/A

[SupportLightWareLiDAR]

@adpjhu , thank you for raising this issue with LightWare and ArduPilot, I am working on correcting the guide.

[rishabsingh3003]

Thanks, I have never tested the GRF 500, I have only tested the GRF250 and I know it works on that. I'll ping the lightware team to see if they can confirm the issue.