Create i2c_master_register_read.ino

arduino/i2c_master_register_read.ino

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+// Wire Master Reader
+// by Nicholas Zambetti <http://www.zambetti.com>
+
+// Demonstrates use of the Wire library
+// Reads data from an I2C/TWI slave device
+// Refer to the "Wire Slave Sender" example for use with this
+
+// Created 29 March 2006
+
+// This example code is in the public domain.
+
+// modified by Alan Johnston to show reading registers 0 - 3
+// code based on https://forum.arduino.cc/index.php?topic=211587.0
+
+#include <Wire.h>
+#define I2C_ADDRESS 0x4B
+#define REGISTER_0 0x00
+#define REGISTER_1 0x01
+#define REGISTER_2 0x02
+#define REGISTER_3 0x03
+
+uint8_t reg; // I2C read register
+
+void setup() {
+  Wire.begin();        // join i2c bus (address optional for master)
+  Serial.begin(9600);  // start serial for output
+  pinMode(LED_BUILTIN, OUTPUT);
+  Serial.println("Starting");
+}
+
+void loop() {
+  for (reg=0; reg < 4; reg++) {
+    delay(5000);
+    digitalWrite(LED_BUILTIN, HIGH);
+    Wire.beginTransmission(I2C_ADDRESS);
+    Wire.write(reg);
+    Wire.endTransmission();
+    delay(100);
+    digitalWrite(LED_BUILTIN, LOW);
+  
+    
+    Wire.requestFrom(I2C_ADDRESS, 2);    // request 2 bytes from I2C device
+    byte LSB = Wire.read();
+    byte MSB = Wire.read();
+  
+    uint16_t register_value = ((MSB << 8) | LSB);
+    
+    Serial.print("Read ");
+    Serial.print(register_value);
+    Serial.print(" from register ");
+    Serial.println(reg);
+  }
+}