Connect GND, SDA and SCL between the STM32 and other microcontroller.
STM32 slave
#include <Wire.h>
volatile int val;
void incomingData(int n)
{
digitalWrite(PC13, HIGH);
val = Wire.read();
Serial.println(val);
digitalWrite(PC13, LOW);
}
void setup() {
Wire.setSDA(PB7);
Wire.setSCL(PB6);
Wire.begin(9); // join i2c bus with address #9
Wire.onReceive(incomingData); // register event
Serial.begin(115200);
}
void loop() {
if (val > 10) {
// do something
}
}
Master writer
Example from the wire.h library
// Wire Master Writer
// by Nicholas Zambetti <http://www.zambetti.com>
// Demonstrates use of the Wire library
// Writes data to an I2C/TWI slave device
// Refer to the "Wire Slave Receiver" example for use with this
// Created 29 March 2006
// This example code is in the public domain.
#include <Wire.h>
int led = LED_BUILTIN;
void setup()
{
pinMode(led, OUTPUT);
Wire.begin(); // join i2c bus (address optional for master)
}
byte val = 0;
void loop()
{
digitalWrite(led, HIGH); // briefly flash the LED
Wire.beginTransmission(9); // transmit to device #9
Wire.write(val); // sends one byte
Wire.endTransmission(); // stop transmitting
digitalWrite(led, LOW);
val++;
delay(500);
}
