$ python3 -m pip install pyserial

Further information for RPi prmissions

Simple communicate to Arduino

Arduino code:

void setup()
{
    Serial.begin(9600);
}

void loop()
{
    Serila.println("Hi to you");
    delay(500);
}

RPi code:

from os import system
import serial


def ReceivedData(port):
    ser = serial.Serial(port, 9600, timeout=1)
    ser.reset_input_buffer()
    while True:
        if ser.in_waiting > 0:
            line = ser.readline().decode('utf-8').rstrip()
            return line

system("ls /dev/tty* | grep ACM > command_output.txt")
with open ("./command_output.txt", 'r') as port_name:
    port = port_name.readline()
    # There is a '\n' at the end of the port that has to be removed
    port = port.strip()

if len(port)>0:
    arduino_port = port
    data = ReceivedData(arduino_port)
    print(data)
else:
    print("Error: No Device is connected")

NOTE:  if the error

in open raise SerialException(msg.errno, "could not open port {}: {}".format(self._port, msg)) serial.serialutil.SerialException: [Errno 13] could not open port /dev/ttyACM0: [Errno 13] Permission denied: '/dev/ttyACM0'

pops up,  run the following code block

$ sudo chmod 666 /dev/ttyACM0

Further information

Send and Receive data via Serial port

Arduino code

#define LED_pin 13

void setup()
{
    Serial.begin(9600)
    pinMode(LED_pin, OUTPUT);
}

void loop()
{
    String command = ""
    while(Serial.available()>0)
    {
        command = Serial.readString();

        if (command == "LED on")
        {
            Serial.println("LED is on");
            digitalWrite(LED_pin, HIGH);
        }
        else if(command == "LED off")
        {
            Serial.println("LED is off");
            digitalWrite(LED_pin, LOW);
        }
    }
}

RPI code

from os import system
from serial import Serial
import time

validCommands = ['LED on','LED off']

def discoverConnectedPort():
    ## find 'ACM' in the list of ports and write it in a txt file
    system("ls /dev/tty* | grep ACM > command_output.txt")
    with open ("./command_output.txt", 'r') as grepOutputFile:
        portName = grepOutputFile.readline()
        # There is a '\n' at the end of the port that has to be removed
        portName = portName.strip()
        ## it returns a string like '/dev/ttyACM1'
        return portName

with Serial(port = discoverConnectedPort(), baudrate= 9600, timeout=1) as arduino:
    if arduino.isOpen():
        # split the port name string by / and create a list of it, print the last element of it
        # /dev/ttyACM1 -> ['dev', 'ttyACM1']   
        print("{} connected!".format(arduino.port.split(sep='/')[-1]))  
        while True:
            command = input("your command >> ")
            if (command == 'exit'):
                exit()

            time.sleep(0.1) #wait for serial to open  
            # Encode the command to utf-8
            arduino.write(command.encode())

            if command in validCommands:
                # wait until something is in the buffer
                while arduino.inWaiting()==0: pass
                # if there is more that 0 byte in the buffer, read it
                if (arduino.inWaiting() > 0):
                    # There is a '\n' at the end of the message that has to be removed
                    message = arduino.readline().decode('utf-8').rstrip()
                    print(message)
                    # reset input buffer
                    arduino.flushInput()

NOTE:  if you want to send muliple lines to RPi, you need to change message = arduino.readline().decode('utf-8').rstrip() to th efollowing code block

for line in arduino.readlines():
    message = line.decode('utf-8').rstrip()
    print(message)

Further information

Remote Connection (via SSH)

Find your Raspberry pi Username and IP (host ip)

Username:

$ whoami

Host IP:

$ hostname -I

Note: You should enabled port 22 before trying to connect to your pi from the other device.

HOW?

$ apt install ufw

$ ufw allow ssh

$ ufw enable

Check the status of your firewall:

$ ufw status

Then, You can ssh to your PI:

$ ssh [username]@[IP address]

Congratulations!

If you got this Error message:

ssh: connect to username@hostname_id port 22: Connection refused

make sure you have installed openssh-server.

1- To install it

$ sudo apt install openssh-server

2- check the status of ssh service, make ssh service start.

$ sudo service ssh status    
$ sudo service ssh start
 ```
3- Check whether port 22 in that system is blocked by iptables. Just allow port in iptables and then check.
```shell
$ sudo iptables -A INPUT -p tcp --dport ssh -j ACCEPT

4- Else change port number of ssh from 22 to 2222 by editing

$ vi /etc/ssh/sshd_config         
$ /etc/init.d/ssh restart.

Hope you Enjoy!

Camera

First you need to check if camera is connected properly.

Get a fame

$ raspistill -o test.jpg

If you get  mmal: No data received from sensor. Check all connections, including the Sunny one on the camera board error:

Make sure that the sunny connector is firmly attached. You jist need to remove the sunny connector and fixed in the same place. Then camera world work fine.

The sunny connector