Raspberry Pi 3B+ i2c does not detect LIDAR Lite v3

Help & Support Robot Parts
1

Hello,

I am trying to connect my Garmin LIDAR Lite v3 sensor to my Raspberry Pi 3B+ via i2c interface. However i2cdetect on the command line returns dashes for every address.

I’ll try my best to clearly define my current progress.

RASPBERRY PI:
** Raspbian Stretch With Desktop**
Version: June 2018
Kernel Version: 4.14.50
I2C Configuration:
Installed i2ctools.
i2c activated in raspi-config
boot/config.txt file shows i2c_arm=on
Connections
Currently connecting gpio pin 3 (SDA) to the blue wire, pin 5 (SCL) to the green wire.
gpio pin 4 (5V source) to red wire, pin 6 (GND) to black wire.
Pin layout on Pi: raspberrypi-spy.co.uk/2012/06/simple-guide-to-the-rpi-gpio-header-and-pins/#prettyPhoto/0/

LIDAR Lite v3:
Observations:
Connected (w 10v470uF capacitor instead of recommended 680uF) according to i.stack.imgur.com/LaNj9.png
Faint red light flashing (can be seen in a crack next to where the colored wires are plugged into LIDAR)
Red and black wires are supplied 4.95V
Blue and green wires are supplied 3.26V
Capacitor polarity is correct
Here an image of set-up: drive.google.com/file/d/1oF645dk09v5GRPeecGbqQOj3-Qm11i8B/view?usp=sharing

When I run “i2cdetect -y 1”, I get dashes for all addresses: drive.google.com/file/d/1csh1fjeKv_HbvK-B8JfrbbANgB9CXFdv/view?usp=sharing
I should be getting a result for the LIDAR Lite address 0x62

What I’ve tried:
Reinstalling Raspbian image.
Downgrading kernel (which caused my pi to not start up)
Using Bus 0 (may have not set it up correctly)
running i2cdetect with -r and -q flags instead
external 5v power source (my flashing red light turns into a steady red light)
Removing the capacitor

I get the same result every time. There is a possibility that my LIDAR Lite is broken. However, it is an expensive piece of equipment and would like to make sure I exhausted all potential fixes.

Thanks!

2

Hey,

You may want to check the topic here. In the last few posts, some member of our community mentions using the RPi 3B+.

Please note that the LLV3 does not support I2C repeated starts, which is the main reason these I2C issues started appearing last year. For the most part, it seems to be due to a driver change where the code ignores (i.e.: a bug in the I2C driver) a call that says to not use repeated starts and uses them anyways, making the sensor unable to respond/function.

There are multiple solutions for various situations so you’ll need to read a bit in that topic and see what fits yours. You’ll most likely need to tell it to use a previous driver or make a compatible kernel downgrade (or some other wizardry :stuck_out_tongue: ).

We hope this helps.

Sincerely,

3

Hello, I am unsure what the issue exactly was. However, when i tried using the HP version, i2cdetect was able to see the address of the sensor.

It might be a compatibility issue, it might be a broken v3… However, I would recommend paying a few extra dollars to get the HP – especially if you have the raspberry pi 3B+.

4

Since the LLV3HP actually supports repeated starts (the manufacturer added that feature since they were making a new product) is most likely why it works.