Communication between Raspberry pi and MegaPi¶

This part explains you how etablish a simple comunication between Python (RPI) and Arduino C (Makeblock boards) using PySerial and how works this simple communication in order to setup new capabilities.

Basic working of the communication¶

First we will see how to adapt and run an example for RPI and Makeblock boards communication.

Requirement¶

basic knowledge of Arduino
basic knowledge of Linux command (cd, ls, use of tab key for auto-completion)

Set-up the communication¶

Arduino configuration¶

Open ~/Documents/control_rover1.0/control_rover1.0.ino in Arduino IDE. From ssh (see the Working in SSH topic), you can do arduino control_rover1.0.ino but it could be slow.

This is the Arduino code to process what Python part are sending.

Depending on the type of board you’re using, you need to modify the header file to match.

For example, if you’re using a mCore. You should change #include <MeOrion.h> to #include <MeMCore.h> Corresponding boards and there header file are:

Orion <> MeOrion.h ; BaseBoard <> MeBaseBoard.h ; mCore <> MeMCore.h ; Shield <> MeShield.h ; Auriga <> MeAuriga.h ; MegaPi <> MeMegaPi.h

for the moment, you just have to change the port and objects’ name depending on your board (MeMegaPiDCMotor..). To find the good one, you can try a motor example by clicking in Arduino IDE on File/Examples/makeblock-librairies-master

#include <SoftwareSerial.h>
#include "MeMegaPiPro.h" //Insert here your makeblock boards.

MeSmartServo mysmartservo(PORT5);   //UART2 is on port 5 //You can keep this even if you don't have the SmartServo

//material declarations,
MeMegaPiDCMotor motor1(PORT1B); //right front wheel
MeMegaPiDCMotor motor2(PORT2B); // right back wheel
MeMegaPiDCMotor motor3(PORT3B); // left front wheel
MeMegaPiDCMotor motor4(PORT4B); // left back wheel
MeRGBLed led(PORT_9); //You can keep this even if you don't have the module

Connect your makeblock board at your Raspberry PI thanks to a USB-B cable and upload your code. The most harder is done ! If you have a problem don’t hesitate to create a github issue (see Support)

launch Python-Arduino communication example¶

On a terminal :

the control_example.py uses sockets to send datas (providing by sensors,etc. i.e. by Arduino). Like this you can receive data in another PC (by changing sock.connect(('127.0.0.1', 8001))). For this example, we just show the values in another terminal. Write:
nc -l 8001

- activate comRPI virtual environment (see Configure a Python virtual environment)

On another terminal:
workon comRPI

PySerial is already installed on this virtual environment moreover if you want to create another venv you can pip install pyserial after activate your new venv.

Check on Arduino IDE that you have the good portname. You can see the “Serial Port” entry in the Arduino “Tools” menu if it’s not /dev/ttyUSB0, edit control_example.py (using nano ou Gedit) and change the value of portname by the good one.

Finaly write:

(comRPI) makeblock@makeblock-desktop: cd ~/Documents/RoverExamples/Python-Arduino-example
(comRPI) makeblock@makeblock-desktop: python control_example.py