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Loss of range on Lidar-Lite v3
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Please be positive and constructive with your questions and comments.

Loss of range on Lidar-Lite v3

by lexdm3 on Mon Aug 24, 2020 2:16 pm

I bought a Lidar-Lite v3 last September and have been using it sparingly in development of an interactive system for kids in a rehab hospital. I have it interfaced using level-shifted I2C to a Grand Central M4-based controller.

I noticed some months back that the range of the Lidar-Lite wasn't as great as it used to be. I could pick up people at up to 90 feet away before and that dropped to about 55 feet.

Needing a second Lidar-Lite v3 anyway, I bought one from Mouser (Adafruit was out of stock at the time) and tested with that in the same system. The range with the new one is just fine. I have alternated between the original and new sensors and see that the older one only goes out to 52-61% of the range of the new one depending on the Lidar operating mode selected.

I am confident that I am using this correctly, that it is interfaced and powered according to spec (5V supply and I2C signals) and that it has not been damaged or dropped. It works just fine except that the distance capability is reduced.

I have a lot of experience with things like this (see my Adafruit orders!) and I'm quite sure that I'm not making a rookie mistake with this. However, if there's a way to reset or recalibrate the L-L v3, please let me know how to do it. I didn't find it in the data sheet.

Could I exchange this for a new one?

Thanks. --Dan

lexdm3
 
Posts: 26
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Re: Loss of range on Lidar-Lite v3

by mikeysklar on Mon Aug 24, 2020 5:39 pm

Hi Dan,

Can you tell us some more about your 5v supply you are using to drive the Garmin Lidar-Lite v3 that is showing limited range? Have you been able to confirm the same behavior with a benchtop power supply and in-line capacitor to make sure it is a super clean power source?

Our replacements are limited to a 30-day window so we cannot swap the original Adafruit model for you at this point.

Garmin has a page describing how the Garmin LIDAR-Lite v3 is self calibrating with no hardware or software adjustments. There is another model the v3HP which Garmin calibrates before shipping, but is not user setable.

https://support.garmin.com/en-NZ/?faq=D ... NcayIuO36A

The LIDAR-Lite v3 sensor is self-calibrating and no factory “zero” calibration is performed when the sensor is manufactured. There may be instances where a consistent small offset between actual distance and measured distance may appear. This can be corrected by implementing a distance correction in the application software being used.

The LIDAR-Lite v3HP has been factory calibrated to eliminate any offset to distance measurements.

mikeysklar
 
Posts: 1974
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Re: Loss of range on Lidar-Lite v3

by lexdm3 on Tue Sep 01, 2020 9:20 am

Hi and thanks for your response. I’m very sorry to have not replied earlier. My hope was to run some more tests on the two Lidar sensors and report the results back here but I have had no chance to do that. I’m away from the systems now until next week but will test them then.

But I can answer your power supply question. I’m powering two of the CPUs in the system (AF Grand Central M4 and AF M0 Express) with one of your 5V 2.5A supplies. I’m using an AF level converter to shift the I2C levels from 3.3 to 5V and I’m running 5v directly to the Lidar sensor. I have the proper 680uF cap across the 5V and ground leads going to the Lidar. So I think that is all correct.

Here’s why I believe it’s the Lidar sensor itself - If I substitute only the Lidar sensor itself into the system, I get those very different and very consistent max range differences. Everything else is exactly the same - System, power, code, etc. I can plug in the new one and get longer range readings. Then I take that out and plug in the original one and get lower range readings.

Again, my apologies for not replying earlier. Thanks so much for your help. I’ll be back next week with more information.

Dan

lexdm3
 
Posts: 26
Joined: Thu Mar 12, 2015 6:44 pm

Re: Loss of range on Lidar-Lite v3

by mikeysklar on Tue Sep 01, 2020 11:17 am

Dan,

I believe your best support option at this point will be to work with Garmin directly. Since we are a reseller that works on providing communication with the device it is a bit of a black box to us in terms of long term calibration offsets.

https://support.garmin.com/en-US/?partN ... tab=topics

mikeysklar
 
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Re: Loss of range on Lidar-Lite v3

by lexdm3 on Tue Sep 01, 2020 11:58 am

Thanks! I’ll contact Garmin. I appreciate the help. Dan

lexdm3
 
Posts: 26
Joined: Thu Mar 12, 2015 6:44 pm

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