diff --git a/firmware/open_evse/CHANGELOG b/firmware/open_evse/CHANGELOG
index 0b3bb708..f0f47843 100644
--- a/firmware/open_evse/CHANGELOG
+++ b/firmware/open_evse/CHANGELOG
@@ -1,5 +1,8 @@
 Change Log
 
+2021119 SCL V7.1.5
+- added RAPI $GI command to get AVR serial number. enable with MCU_ID_LEN
+
 20210911 SCL V7.1.4
 - fixed minor bug.. temperature checking was only being done in STATE C. So
   if temperature dropped below the restore threshold after transition out of
diff --git a/firmware/open_evse/open_evse.h b/firmware/open_evse/open_evse.h
index c7f38366..97507738 100644
--- a/firmware/open_evse/open_evse.h
+++ b/firmware/open_evse/open_evse.h
@@ -41,7 +41,7 @@
 #define clrBits(flags,bits) (flags &= ~(bits))
 
 #ifndef VERSION
-#define VERSION "D7.1.3"
+#define VERSION "D7.1.5"
 #endif // !VERSION
 
 #include "Language_default.h"   //Default language should always be included as bottom layer
@@ -61,6 +61,9 @@ typedef unsigned long time_t;
 #define RELAY_HOLD_DELAY_TUNING // enable Z0
 #endif // OEV6
 
+// enable $GI
+#define MCU_ID_LEN 10
+
 // auto detect L1/L2
 #define AUTOSVCLEVEL
 
diff --git a/firmware/open_evse/rapi_proc.cpp b/firmware/open_evse/rapi_proc.cpp
index 1230a536..83b4d83e 100644
--- a/firmware/open_evse/rapi_proc.cpp
+++ b/firmware/open_evse/rapi_proc.cpp
@@ -33,6 +33,18 @@
 const char RAPI_VER[] PROGMEM = RAPIVER;
 
 
+#ifdef MCU_ID_LEN
+// mcuid *must* be of size MCU_ID_LEN
+#include <avr/boot.h>
+void getMcuId(uint8_t *mcuid)
+{
+  for (int i=0;i < MCU_ID_LEN;i++) {
+    mcuid[i] = boot_signature_byte_get(0x0E + i);
+  }
+}
+#endif // MCU_ID_LEN
+
+
 // convert 2-digit hex string to uint8_t
 uint8_t htou8(const char *s)
 {
@@ -462,6 +474,25 @@ int EvseRapiProcessor::processCmd()
       }
       break;
 #endif // CHARGE_LIMIT
+#ifdef MCU_ID_LEN
+    case 'I': // get MCU ID
+      {
+        uint8_t mcuid[MCU_ID_LEN];
+        getMcuId(mcuid);
+        char *s = buffer + strlen(buffer);
+        *(s++) = ' ';
+        for (int i=0;i < 6;i++) {
+          *(s++) = mcuid[i];
+        }
+        for (int i=6;i < MCU_ID_LEN;i++) {
+          sprintf(s,"%02X",mcuid[i]);
+          s += 2;
+        }
+        bufCnt = 1; // flag response text output
+        rc = 0;
+      }
+      break;
+#endif // MCU_ID_LEN
 #ifdef KWH_RECORDING
     case 'K': // set accumulated kwh
       g_EnergyMeter.SetTotkWh(dtou32(tokens[1]));
diff --git a/firmware/open_evse/rapi_proc.h b/firmware/open_evse/rapi_proc.h
index 296ebaea..7aaadad2 100644
--- a/firmware/open_evse/rapi_proc.h
+++ b/firmware/open_evse/rapi_proc.h
@@ -269,6 +269,15 @@ GH - get cHarge limit
  kWh = 0 = no charge limit
  $GH^2B
 
+GI - get MCU ID - requires MCU_ID_LEN to be defined
+ response: $OK mcuid
+ mcuid: AVR serial number
+        mcuid is 6 ASCII characters followed by 4 hex digits
+        first hex digit = FF for 328P
+  WARNING: mcuid is guaranteed to be unique only for the 328PB. Uniqueness is
+	unknown in 328P. The first 6 characters are ASCII, and the rest are
+	hexadecimal.
+
 GM - get voltMeter settings
  response: $OK voltcalefactor voltoffset
  $GM^2E
@@ -333,7 +342,7 @@ Z0 closems holdpwm
 
 #ifdef RAPI
 
-#define RAPIVER "5.1.3"
+#define RAPIVER "5.1.4"
 
 #define WIFI_MODE_AP 0
 #define WIFI_MODE_CLIENT 1