diff --git a/arduino/i2c_master_register_read.ino b/arduino/i2c_master_register_read.ino
index e8c7f1a4..a2a6f789 100644
--- a/arduino/i2c_master_register_read.ino
+++ b/arduino/i2c_master_register_read.ino
@@ -11,6 +11,8 @@
 
 // modified by Alan Johnston to show reading registers 0 - 3
 // code based on https://forum.arduino.cc/index.php?topic=211587.0
+//
+// This code is to simulate the Raspberry Pi acting as I2C bus master 
 
 #include <Wire.h>
 #define I2C_ADDRESS 0x4B
@@ -46,7 +48,7 @@ void loop() {
     uint16_t register_value = ((MSB << 8) | LSB);
     
     Serial.print("Read ");
-    Serial.print(register_value);
+    Serial.print(register_value, HEX); // display register value in HEXADECIMAL
     Serial.print(" from register ");
     Serial.println(reg);
   }
diff --git a/arduino/i2c_slave_register_read.ino b/arduino/i2c_slave_register_read.ino
index a4890778..e59935cc 100644
--- a/arduino/i2c_slave_register_read.ino
+++ b/arduino/i2c_slave_register_read.ino
@@ -1,3 +1,9 @@
+// Arduino I2C slave for reading 16 bit registers
+//
+// by Alan Johnston
+//
+// based on 
+
 #include <Wire.h>
 #define I2C_ADDRESS 0x4B
 #define REGISTER_0 0x00
@@ -6,10 +12,8 @@
 #define REGISTER_3 0x03
 
 uint8_t reg; // I2C read register
-unsigned int reg_0_value = 41151;  
-unsigned int reg_1_value = 53124;
-unsigned int reg_2_value = 65535;
-unsigned int reg_3_value = 0;
+
+unsigned int reg_0_value, reg_1_value, reg_2_value, reg_3_value;  // register variables
 
 void setup() {
 
@@ -24,6 +28,13 @@ void setup() {
 
 void loop() {
   Serial.println("Waiting for register read");
+  
+  // Read from sensor here and set register variables
+  reg_0_value = 57007;   // decimal values of registers for testing
+  reg_1_value = 48879;
+  reg_2_value = 3790;
+  reg_3_value = 4613;
+  
   delay(5000);
 }
 
@@ -40,19 +51,19 @@ void requestEvent() {
   if (reg == REGISTER_0) {
     Wire.write((uint8_t *)&reg_0_value, sizeof(reg_0_value));
     Serial.print("Writing value ");
-    Serial.println(reg_0_value);
+    Serial.println(reg_0_value, DEC);  // writing register value in DECIMAL format
   } else if (reg == REGISTER_1) {
     Wire.write((uint8_t *)&reg_1_value, sizeof(reg_1_value));
     Serial.print("Writing value ");
-    Serial.println(reg_1_value);
+    Serial.println(reg_1_value, DEC);
   } else if (reg == REGISTER_2) {
     Wire.write((uint8_t *)&reg_2_value, sizeof(reg_2_value));
     Serial.print("Writing value ");
-    Serial.println(reg_2_value);
+    Serial.println(reg_2_value, DEC);
   } else if (reg == REGISTER_3) {
     Wire.write((uint8_t *)&reg_3_value, sizeof(reg_3_value));
     Serial.print("Writing value ");
-    Serial.println(reg_3_value);
+    Serial.println(reg_3_value, DEC);
   } else {
     Serial.println("Unknown register");
   }