Help needed for Laser Rangefinder for PTZ cameras

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1

Hi All,

This is my first post. I have been using HA for a while now and my latest project is going to be using a laser rangefinder like this: https://www.robotshop.com/uk/sf30-c-laser-rangefinder-100m.html to control three PTZ cameras along a 100m access road.

I already have HA controlling the PTZ cameras by using REST commands to change their position, now I would like to use a rangefinder to tell HA how far along a 100m road a car is and move the PTZs to any of 10 zones to “track” it.

I am thinking I will need to use an arduino to take the PWM input from the rangefinder and output to one of 10 pins that will be connected to a NodeMCU for HA. The arduino will output pin 1 if the vehicle is 0-10m away, pin 2 if it’s 10m-20m away etc.

I would appreciate any advice anyone could give me especially as the rangefinder is 5v and the NodeMCU is 3.3v.

Thanks in advance,
Ben

2

That seems overly complicated. Without reading the documentation in detail, why not connect it to a esp8266 of esp32 through a logic level shifter and output the distance, rather than a range. BTW esphome seems a good place to start.

3

Thanks for your suggestions. Would you mind elaborating as I have no experience with esphome? How would HA read the distance and react to it?

4

I have read the specifications of the sensor and it says: “The analog interface on the main connector produces a linear voltage of between 0.00 V and 2.56 V that is proportional to the
measured distance”.

Can I just connect this to A0 on a NodeMCU?

Thanks

5

I believe you could, but you’d need a voltage divider as A0 reads voltage between 0 and 1.0v.

https://esphome.io it is probably a bit to get your head around, but it is a programming framework to program an esp8266 or esp32 to end up with a device that will read sensors, respond to attached switches and integrate with home assistant, and indeed anything that uses mqtt. You simply write a yaml file, click upload, and it writes a completed firmware to your device.

An analog sensor example is here https://esphome.io/cookbook/temt6000.html.

I have to say that device you pointed to is very expensive! There may be cheaper alternatives. I’ll look around.

6

Thanks. I really appreciate your help

7

Not on the Wemos D1 mini. It takes in 0-3.3V on A0. ESPHome scales it to 0-1V.

The NodeMCU-32 can take up to 3.9V using the built in attenuator (ESPHome supported).

8

Hi,

I have found this much cheaper 100m rangefinder: https://www.unmannedtechshop.co.uk/product/benewake-tf03-lidar-led-rangefinder-ip65-100-m/

It outputs “Hexadecimal distance value; Character string;” via UART

What would my options be for connecting this to a esp8266?

Thanks

9

I have no idea how you monitor the incoming data for your string though.

10

I can’t find an arduino library for it. It is available from sparkfun and others.

11

You are right of course.

As for the benewake, this article shows how to get data - it uses one of their shorter range models, but it seems to use the same protocol. https://www.instructables.com/id/Benewake-TFmini-Inexpensive-LiDAR-With-Teensy-35/