diff --git a/README.md b/README.md
index 525020d..55b78da 100644
--- a/README.md
+++ b/README.md
@@ -178,8 +178,8 @@ An external display can be optionally connected. For details and wiring instruct
 | NodeMCU V2 (aka v1.0)             | ESP8266        | yes             | yes       | yes | no      | nodemcuv2 |
 | Raspberry Pi Pico                 | RP2040         | yes             | yes       | yes | no      | pico |
 | Arduino Pro Mini (ATmega328 8mHz) | ATmega328      | yes             | yes       | no  | no      | pro8mhzatmega328 |
+| SAMD21 M0-Mini                    | SAMD21         | yes             | yes       | no  | no      | samd21_m0_mini |
 | Teensy LC                         | MKL26Z64VFT4   | yes             | yes       | yes | no      | teensylc |
-| Arduino Zero (USB)                | SAMD21         | yes             | yes       | yes | no      | zerousb |
 
 _\*7_: These boards have onboard USB but by default do not support firmware upload over USB or serial over USB. For upload use a STLink programmer or USB to serial adapter.
 
diff --git a/platformio.ini b/platformio.ini
index 8584f66..8c01008 100644
--- a/platformio.ini
+++ b/platformio.ini
@@ -63,8 +63,8 @@ default_envs =
     ; nodemcuv2                         ; NodeMCU V2
     ; pico                              ; Raspberry Pi Pico
     ; pro8mhzatmega328                  ; Arduino Pro Mini 3.3V 8Mhz
+    ; samd21_m0_mini                    ; SAMD21 M0-Mini
     ; teensylc                          ; Teensy LC
-    ; zerousb                           ; Arduino Zero (USB)
 
 
 ; ------------------------------------------------------------------------------
@@ -755,6 +755,27 @@ build_flags =
     ; -D USE_LED                 ; NOT SUPPORTED
     ; -D USE_DISPLAY             ; Requires external I2C OLED display
 
+
+[env:samd21_m0_mini]
+; SAMD21 M0-Mini (SAMD21)
+; The SPI pins are available on the ICSP connector pins on top of the PCB
+; No display
+platform = atmelsam
+board = zeroUSB
+framework = arduino
+monitor_speed = ${common.monitor_speed}      
+lib_deps =
+    ${common.lib_deps}    
+    ${mcci_lmic.lib_deps}
+build_flags =
+    ${common.build_flags}
+    ${mcci_lmic.build_flags} 
+    -D BSFILE=\"boards/bsf_samd21_m0_mini.h\"
+    -D MONITOR_SPEED=${common.monitor_speed}
+    -D USE_SERIAL
+    ; -D USE_LED                 ; NOT SUPPORTED
+    ; -D USE_DISPLAY             ; Requires external I2C OLED display
+
  
 [env:teensylc]
 ; Teensy LC (NXP MKL26Z64VFT4)
@@ -776,25 +797,4 @@ build_flags =
     ; -D USE_DISPLAY             ; Requires external I2C OLED display
 
 
-[env:zerousb]
-; Arduino Zero USB (SAMD21)
-; The SPI pins are available on the ICSP connector pins on top of the PCB
-; No display
-platform = atmelsam
-board = zeroUSB
-framework = arduino
-monitor_speed = ${common.monitor_speed}      
-lib_deps =
-    ${common.lib_deps}    
-    ${mcci_lmic.lib_deps}
-build_flags =
-    ${common.build_flags}
-    ${mcci_lmic.build_flags} 
-    -D BSFILE=\"boards/bsf_zerousb.h\"
-    -D MONITOR_SPEED=${common.monitor_speed}
-    -D USE_SERIAL
-    -D USE_LED
-    ; -D USE_DISPLAY             ; Requires external I2C OLED display
-
-
 ; end of file   
\ No newline at end of file
diff --git a/src/boards/bsf_zerousb.h b/src/boards/bsf_samd21_m0_mini.h
similarity index 85%
rename from src/boards/bsf_zerousb.h
rename to src/boards/bsf_samd21_m0_mini.h
index 4a6e7cf..e21f225 100644
--- a/src/boards/bsf_zerousb.h
+++ b/src/boards/bsf_samd21_m0_mini.h
@@ -1,9 +1,9 @@
 /*******************************************************************************
  * 
- *  File:         bsf_zerousb.h
+ *  File:         bsf_samd21_m0_mini.h
  * 
- *  Function:     Board Support File for Arduino Zero (USB Native port)
- *                and SAMD21 M0-Mini, with external SPI LoRa module.
+ *  Function:     Board Support File for SAMD21 M0-Mini
+ *                with external SPI LoRa module.
  * 
  *  Copyright:    Copyright (c) 2021 Leonel Lopes Parente
  * 
@@ -14,6 +14,10 @@
  *  Description:  This board has onboard USB (provided by the MCU).
  *                It supports automatic firmware upload and serial over USB.
  *                No onboard display. Optionally an external display con be connected.
+ *
+ *                On some boards a user LED is present while on
+ *                others it PA17 / 13 which is shared which is also used for SPI SCK.
+ *                Therefore onboard LED is not supported by LMIC-node.
  * 
  *                The SPI pins are located on the top side of the PCB as part of 
  *                the ICSP connector. It is strange that this board has an ICSP 
@@ -30,7 +34,7 @@
  * 
  *                Leds                GPIO 
  *                ----                ----      
- *                LED   <――――――――――>  PA17 / 13  (LED_BUILTIN, PIN_LED, PIN_LED_13)
+ *                LED                 -          (LED_BUILTIN, PIN_LED, PIN_LED_13)
  *                LED2  <――――――――――>  PB03 / 25  (RX, PIN_LED2, PIN_LED_RXL)
  *                LED3  <――――――――――>  PA27 / 26  (TX, PIN_LED3, PIN_LED_TXL)
  * 
@@ -53,7 +57,7 @@
  *  Docs:         https://docs.platformio.org/en/latest/boards/atmelsam/zeroUSB.html
  *
  *  Identifiers:  LMIC-node
- *                    board:         zerousb
+ *                    board:         samd21_m0_mini
  *                PlatformIO
  *                    board:         zeroUSB
  *                    platform:      atmelsam
@@ -65,12 +69,12 @@
 
 #pragma once
 
-#ifndef BSF_ZEROUSB_H_
-#define BSF_ZEROUSB_H_
+#ifndef BSF_SAMD21_M0_MINI_
+#define BSF_SAMD21_M0_MINI_
 
 #include "LMIC-node.h"
 
-#define DEVICEID_DEFAULT "zero-usb"  // Default deviceid value
+#define DEVICEID_DEFAULT "samd21-m0-mini"  // Default deviceid value
 
 // Wait for Serial
 // Can be useful for boards with MCU with integrated USB support.
@@ -100,8 +104,9 @@ const lmic_pinmap lmic_pins = {
 #endif    
 
 #ifdef USE_LED
-    EasyLed led(LED_BUILTIN, EasyLed::ActiveLevel::High);
-#endif
+    #error Invalid option: USE_LED. Onboard LED is not supported.
+    // EasyLed led(<external LED GPIO>, EasyLed::ActiveLevel::Low);
+Endif    
 
 #ifdef USE_DISPLAY
     // Create U8x8 instance for SSD1306 OLED display (no reset) using hardware I2C.
@@ -134,4 +139,4 @@ bool boardInit(InitType initType)
 }
 
 
-#endif  // BSF_ZEROUSB_H_
\ No newline at end of file
+#endif  // BSF_SAMD21_M0_MINI_
\ No newline at end of file