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Controlling an Arduino from a Pi3 using I2C

Demonstration of the I2C protocol. A simple example of turning the Arduino's internal LED on from a Raspberry Pi using I2C

Feb 2, 2018

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i2c

Components and supplies

Raspberry Pi 3 Model B

Arduino UNO

Project description

Code

Python code

python

This is the controller code

1from smbus import SMBus
2
3addr = 0x8 # bus address
4bus = SMBus(1)   # indicates /dev/ic2-1
5bus.write_byte(addr, 0x1) # switch it on
6input("Press   return to exit")
7bus.write_byte(addr, 0x0) # switch it on
8

from smbus import SMBus

addr = 0x8 # bus address
bus = SMBus(1)   # indicates /dev/ic2-1
bus.write_byte(addr, 0x1) # switch it on
input("Press   return to exit")
bus.write_byte(addr, 0x0) # switch it on

Arduino sketch

c_cpp

1// Wire Slave Receiver
2// by Nicholas Zambetti <http://www.zambetti.com>
3
4//  Demonstrates use of the Wire library
5// Receives data as an I2C/TWI slave device
6//  Refer to the "Wire Master Writer" example for use with this
7
8// Created  29 March 2006
9
10// This example code is in the public domain.
11
12// 04-Feb-2018  mcarter adapted
13#include <Wire.h>
14
15const int ledPin = 13; // onboard LED
16static_assert(LOW  == 0, "Expecting LOW to be 0");
17
18void setup() {
19  Wire.begin(0x8);                //  join i2c bus with address #8
20  Wire.onReceive(receiveEvent); // register event
21  pinMode(ledPin, OUTPUT);
22  digitalWrite(ledPin, LOW); // turn it off
23}
24
25void  loop() {
26  delay(100);
27}
28
29// function that executes whenever data is  received from master
30// this function is registered as an event, see setup()
31void  receiveEvent(int howMany) {
32  while (Wire.available()) { // loop through all  but the last
33    char c = Wire.read(); // receive byte as a character
34    digitalWrite(ledPin,  c);
35  }
36}
37

// Wire Slave Receiver
// by Nicholas Zambetti <http://www.zambetti.com>

//  Demonstrates use of the Wire library
// Receives data as an I2C/TWI slave device
//  Refer to the "Wire Master Writer" example for use with this

// Created  29 March 2006

// This example code is in the public domain.

// 04-Feb-2018  mcarter adapted
#include <Wire.h>

const int ledPin = 13; // onboard LED
static_assert(LOW  == 0, "Expecting LOW to be 0");

void setup() {
  Wire.begin(0x8);                //  join i2c bus with address #8
  Wire.onReceive(receiveEvent); // register event
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, LOW); // turn it off
}

void  loop() {
  delay(100);
}

// function that executes whenever data is  received from master
// this function is registered as an event, see setup()
void  receiveEvent(int howMany) {
  while (Wire.available()) { // loop through all  but the last
    char c = Wire.read(); // receive byte as a character
    digitalWrite(ledPin,  c);
  }
}

Python code

python

This is the controller code

1from smbus import SMBus
2
3addr = 0x8 # bus address
4bus = SMBus(1)  # indicates /dev/ic2-1
5bus.write_byte(addr, 0x1) # switch it on
6input("Press  return to exit")
7bus.write_byte(addr, 0x0) # switch it on
8

from smbus import SMBus

addr = 0x8 # bus address
bus = SMBus(1)  # indicates /dev/ic2-1
bus.write_byte(addr, 0x1) # switch it on
input("Press  return to exit")
bus.write_byte(addr, 0x0) # switch it on

Downloadable files

i2c_bb_CpSIoWgNh0.png

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