Using your mBot as a NodeBot

Hardware mbot from makeblock

mBot is the easiest educational robot for kids to learn programming, Arduino and robotics.

Photo from Andrew Fisher

Getting started

1. Drivers

Install the USB Serial driver for your platform found in the drivers folder. Windows users will need to reboot after installing the drivers.

If you're using linux you can skip this step. But instead you will need to add yourself to the dialout group using the command

sudo usermod -a dialout YOUR_USERNAME

You will need to restart or logout and in again afterwards.

2. Install Node.js

Install a recent version of NodeJS installed (v6 is preferred).

3. Build the bot

Build the bot according to the instructions in your kit

4. Install firmware using Interchange

We need to install the firmata firmware onto the board. We do this using a tool called interchange.

Connect the USB cable and switch the on/off switch to on. Open up the command line (command prompt, iTerm, etc) and install interchange globally with the following command.

npm install -g nodebots-interchange

You can install the firmware to work with either USB or Bluetooth with appropriate firmata using the firmata switch on interchange.

To use USB:

interchange install git+https://github.com/Makeblock-official/mbot_nodebots -a uno --firmata=usb

To use Bluetooth:

interchange install git+https://github.com/Makeblock-official/mbot_nodebots -a uno --firmata=bluetooth

If you see Error: no Arduino 'uno' found.. Make sure the on/off switch is on. Also check you have the drivers installed properly. Did you forget to reboot? El Capitan users please make sure you installed the codebenderDriver version located in the driver directory.

If you see the Error: Sending xxxx: receiveData timeout after 400ms, try again after removing the bluetooth module. Replace it afterwards if you are following the bluetooth method.

If you see There was an error downloading the manifest file. try checking your internet connection. If all connectivity fails, ask someone to kindly install firmata for you.

If you see Permission denied, cannot open /dev/ttyUSB0 double check you're in the dialout group and you restarted.

4. (Alternative) Install firmware using Arduino IDE

If you're having troubles with interchange, you can install the firmata firmware using the Arduino IDE however this method is now no longer the preferred option.

Examples

Time to play with some code. There are plenty of examples in the examples directory that you can learn from. You can run from a command line using the command node examples/file.js.

Once you're done with an example, close the program by pressing Ctrl + c twice.

If you get the error Error: Cannot find module 'johnny-five' or another module, try running the command npm install from the mbot_nodebots directory.

LEDs

Lets make the lights flash. There are 2 LEDs on the mbot which are RGB (Red Green Blue) NeoPixel LEDs. These are connected in a strip so you can use node-pixel to control them. An example is examples/leds.js

node examples/leds.js

Buzzer

Use examples/piezo.js - this will make your mbot play some tunes - note that the latency of Bluetooth means this won't work over the bluetooth controller.

Motors

Use examples/motors.js this will drive the mbot around using the arrow keys on your keyboard. You may need to change the details of the directions depending on how you wired up the motors.

Obstacle detection

Use examples/sonar.js to detect the distance to an object. You can use this to stop your robot from running into things.

Button

Your mbot has a little button that you can use to trigger something maybe. Use examples/button.js to detect the button press and do something with it.

Light Sensor

You can read the light level near the mbot - maybe you can make your mbot run away from too much light or move towards more light? Use examples/light.js

Reflectance sensor

Under your mbot is a sensor which you can use to detect lines. Look at examples/reflectance.js to see how to get the data. You can detect lines by getting both sensors to detect a light or dark line (eg black tape on a light surface). Once both sensors are on the line when one drifts off (eg the right sensor) then you can steer back towards the line (turn back to the left in this case).

Once you get this working you can build an effective line following bot.

Bluetooth module

To use the BT module do the following modifications:

• Remove the bluetooth module from the mBot
• Install the bluetooth firmata with instruction below

interchange install git+https://github.com/Makeblock-official/mbot_nodebots -a uno --firmata=bluetooth

• Turn the mbot off, install the bluetooth module, turn the board on again.
• Pair the module (use whatever tool you need to make that work for your OS - usually BT settings in your control panel). It should be called Makeblock. Hopefully nobody else is pairing at the same time.

Test the connection by using a screen terminal such as:

screen /dev/tty.Makeblock-ELETSPP

If this connects you should see the blue LED on the BT module go solid. From there hit the reset button on the board and then you should see something like the following appear on your terminal.

��ymbotFirmata.ino��{�3��l�A�2�U�

If you don't get that, test your connection etc. If you do then proceed.

Now execute

node examples/leds.js /dev/tty.Makeblock-ELETSPP

And you should get blinking lights over BT. You can do the same thing with most of the examples though speed may be an issue in high data rate cases.

2.4GHz wireless module

Install using:

npm install drivers/node-hid

Run example

node examples/wifi_motors.js