One way to connect the Raspberry Pi and Arduino is by connecting the GPIO on the Raspberry Pi and the Serial Pins on the Arduino.
Because there is a voltage difference between the two device on these interface, a voltage divider or logic level converter would be required.
Freeing up UART pins on Raspberry Pi GPIO. By default Raspberry Pi’s UART pins (GPIO 14 and 15) are configured as a serial console. It outputs all the kernel data during boot. We need to free up these pins for our use. For this launch terminal, First make a backup of the file containing kernel parameters cmdline.txt as cmdlinebp.txt. Jun 26, 2019 The Raspberry Pi has 40 GPIO pins that connect to sensors, lights, motors and other devices. Here's a map and detailed explanation of what each does, including on the Pi 4.
Check my article about connecting the two using I2C if you haven’t already seen it. Before we start, we need to set up the Raspberry Pi so it’s ready for serial communication.
Connect a ground pin, GND, on the Raspberry Pi board to the GND pin on the serial device. Connect a +3.3V pin on the Raspberry Pi board to the VCC pin on the serial device. Before continuing, research the manufacturer’s product information to determine which baud rate, data bits, parity, and stop bit settings the serial device supports. The Raspberry Pi UART transmit (TXD) and receive (RXD) pins are assigned to GPIO14 and GPIO15 respectively: Note that these pins use 3.3V logic levels so you can’t connect them directly to devices that uses 5V like an Arduino UNO or a PC. Follow the steps below to start the Raspberry Pi UART communication: Step 1: Connect the serial to USB converter to the Raspberry Pi board as is shown in the circuit. Then plug the Raspberry Pi supply and connect the converter to your PC. Step 2: Go to the Device Manager and find the port number that is connected to the converter. Balabolka text to speech voices.
0. if you have not seen my article on how to remote access your Raspberry Pi, take a look here:
1. In order to use the Raspberry Pi’s serial port, we need to disable getty (the program that displays login screen) by find this line in file /etc/inittab
And comment it out by adding # in front of it
2. To prevents the Raspberry Pi from sending out data to the serial ports when it boots, go to file /boot/cmdline.txt and find the line and remove it
3. reboot the Raspberry Pi using this command: sudo reboot
4. Now, Install minicom
And that’s the end of the software configuration.
Load this program on your Arduino first:
[sourcecode language=”cpp”]
byte number = 0;
void setup(){
Serial.begin(9600); }
void loop(){
if (Serial.available()) { number = Serial.read(); Serial.print(“character recieved: “); Serial.println(number, DEC); } } [/sourcecode]
Then connect your Arduino, Raspberry Pi and Logic Level Converter like this:
This is how the wires are connected.
And this is the GPIO pins on the Raspberry Pi. Make sure you connect the correct pin otherwise you might damage your Pi.
A Simple Example with Minicom
Now to connect to the Arduino via serial port using this command in putty or terminal
When you type a character into the console, it will received by the Arduino, and it will send the corresponding ASCII code back. Check here for ASCII Table. And there it is, the Raspberry Pi is talking to the Arduino over GPIO serial port.
To exit, press CTRL + A release then press Q
Example with Python Program
Using Python programming language, you can make Raspberry Pi do many fascinating stuff with the Arduino when they are connected. Install Py-Serial first:
Raspberry Pi Serial Gpio Pins
Here’s a simple application that sends the string ‘testing’ over the GPIO serial interface
Raspberry Pi 3 B+ Serial Port Pins
[sourcecode language=”python”]
import serial
ser = serial.Serial(‘/dev/ttyAMA0’, 9600, timeout=1) ser.open()
ser.write(“testing”)
try: while 1: response = ser.readline() print response except KeyboardInterrupt: ser.close() Raspberry Pi Serial Terminal
[/sourcecode]
To exit, press CTRL + C
Raspberry Pi Two Serial Ports
Apart from replacing the Login Level Converter with a voltage divider, the way it works is the same as above. Anyway, I will show you a different example to demonstrate this. A voltage divider is basically just two resistors.
There is something you should be aware of before we continue. The RX pin on the Arduino is held at 5 Volts even when it is not initialized. The reason could be that the Arduino is flashed from the Arduino IDE through these pins when you program it, and there are weak external pull-ups to keep the lines to 5 Volts at other times. So this method might be risky. I recommend using a proper level converter, if you insist on doing it this way, try adding a resistor in series to the RX pin, and never connect the Raspberry Pi to Arduino RX pin before you flash the program to Arduino, otherwise you may end up with a damaged Pi!
The Arduino serial pin is held at 5 volts and Raspberry Pi’s at 3.3 volts. Therefore a voltage divider would be required, it’s basically just two resistors.
Here is the program you need to write to the Arduino board.
[sourcecode language=”cpp”]
void setup() {
Serial.begin(9600); }
void loop() {
if (Serial.available() > 0) { int incoming = Serial.read(); Serial.print(“character recieved: “) Serial.print(incoming, DEC); } } [/sourcecode]
Now you can connect directly from your computer to the Raspberry Pi on the tty-device of the Arduino, just like we described above. (type below into your putty)
Raspberry Pi Ttl Serial Pins
And as you type in characters in the console, you should see something like this:
And that’s the end of this Raspberry Pi and Arduino article. There are other ways of connecting, if you don’t already know, you can also use a Micro USB cable. Check out this post: https://oscarliang.com/connect-raspberry-pi-and-arduino-usb-cable/
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