Measurement Error When LIDAR-Lite v4 LED Faces Downward

Sensors
1

Hello,

I’m using a LIDAR-Lite v4 LED and have a question about a measurement issue.

When rotating the sensor around the pitch axis, there is almost no distance error when it is facing upward, but when it is facing downward, the measurement error exceeds 10 cm.

I have already checked and ruled out housing/protective window/bracket internal reflection, target angle/reflectivity, cable tension, and PCB bending as possible causes.

Could this be related to DC bias correction, signal/reference overflow, high-accuracy averaging delay, or a detector/receiver alignment defect that only appears when measuring downward?

Please also let me know whether this symptom could indicate a defective unit and whether it would qualify for replacement.

Thank you.

2

What distances are being measured in their respective directions? Are the materials different?

3

I made all sides 50cm, and used the same A4 paper for the material.

When the lidar faces downward, it measures 40cm.

4

I connected with the existing Arduino, and the problem was solved when I switched the voltage of pin 1 from 5v to 3.3v. What could be the reason?

5

You’re using this model, right? Garmin LIDAR-Lite v4 (Qwiic) Hookup Guide - SparkFun Learn

You can check the board for defects, specifically around here

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The 5v may have just been too noisy as well…how was it being powered?

6

The power was supplied to the laptop using a C-type port, and I ran it using the example code provided by your company.

The pins I’m using are 1, 2, 3, and 4, and the standard way to use power on pin 1 with the I2C protocol is 5V. However, in my case, when the lidar faced downwards, there was a 10cm error at 5V, which was resolved by switching to 3.3V.

What I’m asking is, will there be any lifespan issues if I continue to use 3.3V?

And why does using 3.3V solve the problem?

7

And I use it by connecting it to Arduino by soldering jumper cables directly to those pins, without using a qwiic expansion board.

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8

If you buy Garmin LiDAR v4, are you originally provided with a Qwiic expansion board? I didn’t receive one.

9

We sell both versions:

Since you have the non-qwiic version, their guide notes while 5v power is fine it uses 3.3v io, were you using 3v or 5v?

10

On the Arduino Uno board, a problem was resolved by switching the wiring from 5V to 3.3V.

As shown in the picture, pin 1, the power supply, is set to 5V, and the remaining pins 2, 3, and 4 are directly connected to the Arduino board.

However, I thought there was a level shifter inside the lidar, so I didn’t use any external resistors on the SDL/SDA nodes. Is that the problem?

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11

I’d suspect either that or connections at the sensor side…are they soldered?

12

Yes, it is soldered.

That’s not the important thing, what I want to confirm is whether I can wire Vin to the Arduino’s 3.3v port.

13

Sure - from the guide I linked above: “The I2C bus operates internally at 3.3 Vdc. Internal 13 kiloohm
pull-up resistors ensure this functionality and allow for a simple
connection to the I2C host”

14

Okay, I’ll double-check one more time.

According to the LIDAR-litev4 datasheet, Vin is stated to be 5V, but this means I can plug it into the 3.3V port of the Arduino board, right?

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15

The risky situation is the opposite, where you apply 5v when it is only rated for 3v

The other section on the same page has 3.3v max listed, weird

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16

Yes, you’re right. I’m also confused because there’s other information on the same page.

Is the Vin port 5V? Or is it 3.3V?

17

The specification sheet shows the pin map mapping the Vin port to 5V. It’s really confusing.

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18

Where in the link you provided does it say, “The I2C bus operates internally at 3.3 Vdc. Internal 13 kiloohm pull-up resistors ensure this functionality and allow for a simple connection to the I2C host”? On the contrary, there is content that allows us to infer that there are no internal registers, as shown in the following picture.

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19

A polite request for a response or answer.

20

I thought you had it working with 3v earlier?

The main issue would be attempting to power a 3v device at 5v…this cooks things. Trying to power something a 5v device with 3v will usually result in it either turning on or not

The main thing to look for is to ensure the i2c/IO lines are 3.3v