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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

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Controlling an Arduino from a Pi3 using I2C

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Schematics

i2c_bb_CpSIoWgNh0.png

Code

Arduino sketch

C/C++
// 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
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

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