From f2891ee3484870b5d86028c9ddd74b0721033085 Mon Sep 17 00:00:00 2001
From: Harald Barth <haba@kth.se>
Date: Sun, 14 Mar 2021 22:15:48 +0100
Subject: [PATCH] make generates MAC addr compliant with the IEEE standard by
 setting the Locally Administered bit and clearing the Group Adress bit

---
 DCCTimer.cpp          | 9 ++++++++-
 EthernetInterface.cpp | 2 +-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/DCCTimer.cpp b/DCCTimer.cpp
index 46cd2ea..622b798 100644
--- a/DCCTimer.cpp
+++ b/DCCTimer.cpp
@@ -81,6 +81,8 @@ INTERRUPT_CALLBACK interruptHandler=0;
 
   void   DCCTimer::getSimulatedMacAddress(byte mac[6]) {
     memcpy(mac,(void *) &SIGROW.SERNUM0,6);  // serial number
+    mac[0] &= 0xFE;
+    mac[0] |= 0x02;
   }
 
 #else 
@@ -139,7 +141,12 @@ INTERRUPT_CALLBACK interruptHandler=0;
 
   #include <avr/boot.h> 
   void DCCTimer::getSimulatedMacAddress(byte mac[6]) {
-    for (byte i=0; i<6; i++) mac[i]=boot_signature_byte_get(0x0E + i);
+    for (byte i=0; i<6; i++) {
+      mac[i]=boot_signature_byte_get(0x0E + i);
+    }
+    mac[0] &= 0xFE;
+    mac[0] |= 0x02;
+
   }
 
 #endif
diff --git a/EthernetInterface.cpp b/EthernetInterface.cpp
index 38a0b24..6d21d3c 100644
--- a/EthernetInterface.cpp
+++ b/EthernetInterface.cpp
@@ -54,7 +54,7 @@ EthernetInterface::EthernetInterface()
     DCCTimer::getSimulatedMacAddress(mac);
     DIAG(F("\n+++++ Ethernet Setup. Simulatd mac="));
     for (byte i=0;i<sizeof(mac); i++) {
-        DIAG(F("%x:"),mac[i]);
+        DIAG(F("%s%x:"),mac[i] < 0x10 ? "0" : "", mac[i]);
     }
     DIAG(F("\n"));