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Review on LED Matrix for mBot

Uses a LED Matrix display to show messages in a mBot
LED_Matrix_LMR_test.zip38.56 KB
LED_Matrix_LMR_test_measures_distance.zip38.63 KB

Sometimes it´s good to have a display to show some things in a robot. However displays can be very complicated to handle and energy consuming, unless you use the LED Matrix for mBot.

Here you have a simple but useful display where you can show anything you can imagine with the dot size of a small LED. It´s not very precise but bright and simple enough to show many useful things.

My first test was the "Hello world" in our own version: "LMR", as show on the picture of this article. Code is ready to download and use here.

After that I though could be good to combine two functions of the robot: ultrasound sensor and LED Matrix. Code is here: ultrasound sensor and the LED Matrix. Here you have the video for this experiment (also right above this article).

The program to make this possible is very easy, have a look here:

Distance to LED Matrix test.detail

Basically mBot does this:

  1. sets "y" as the first position for writing on the display
  2. sets "x" is the distance measured by the ultrasonic sensor
  3. shows on the display the distance (x)
  4. waits for 0.001 seconds to measures again and refresh the value

I´m not sure if the sensor and/or the display can go so fast, but I just tried with several values and this one looks fine to show an updated distance as soon as it changes. There are some glitches sometimes in the measure (see the video), I think due to noise. I can filter them out with some more programing, let´s see...

I´ll keep programming new tricks with this display as it can be useful also to interact with humans, included children when playing with the robot!

What application do you think can be interesting?

See past reviews I did about this robot here:


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Good timing, Franciscodr. I was working with the matrix for the first time last night. I couldn't get a program to stay, however. I would get it running from the computer, unplug and turn it back on and it wouldn't run. How do you get the program to upload and run independent of the computer? Was going to look into more of MakeBlock's online documentation tonight.

Thanks OrionBot!

Yes, it´s different when you run the mBot attached to the computer than when it´s alone. When it´s alone you have to give it an automated trigger so the mBot does things by itself, or wait for a command... I will prepare some examples but if you find some online please tell me too as I´m also learning by doing right now ;-)

 love the matrix screen!

I wish I got one to review with my mBot sad face ha ha).

Like OrionBot I have a few more videos to add into my review to cover the software etc.

Also I have a Raspberry Pi A+ which may or may not end up part of mBot :-)

Well, I would like to see how you solve the communication between your mBot and the Raspberry Pi A+. Looking forward to it if you finally do it ;-)

At the moment I'm thinking of just connecting them via USB for now; I will then be able to use basic serial communication to interface the two boards. With the A+ only having the one USB port I am toying with adding an ESP-8266 via the GPIO pins to handle the wi-fi.

At the moment just trying to work out what i can/should do once I have the Pi onboard, ha ha!