diff --git a/ports/bdk-atxx4-mstp/Makefile b/ports/bdk-atxx4-mstp/Makefile
index 5e3d49d7..4fc7122a 100644
--- a/ports/bdk-atxx4-mstp/Makefile
+++ b/ports/bdk-atxx4-mstp/Makefile
@@ -80,6 +80,7 @@ HALSRC = main.c \
 	adc.c \
 	input.c \
 	serial.c \
+	spi-master.c \
 	rs485.c \
 	mstimer-init.c \
 	led.c \
@@ -181,12 +182,15 @@ ifeq (${SEEPROM},128)
 DEFINES += -DSEEPROM_PAGE_SIZE=64
 DEFINES += -DSEEPROM_WORD_ADDRESS_16BIT=1
 endif
+ifeq (${BDK_VERSION},2)
+DEFINES += -DBDK_VERSION=2
+endif
 ifeq (${BDK_VERSION},3)
 DEFINES += -DBDK_VERSION=3
 endif
-
-#ifdef
-
+ifeq (${BDK_VERSION},4)
+DEFINES += -DBDK_VERSION=4
+endif
 
 OPTIMIZE_FLAGS = -mcall-prologues
 OPTIMIZE_FLAGS += -finline-functions-called-once
@@ -281,7 +285,7 @@ AVRDUDE_FLAGS += -P $(AVRDUDE_PORT)
 AVRDUDE_FLAGS += -B 8
 
 # Fuse high byte (0=enable,1=disable):
-# 0x93 = 1 0 0 1   0 0 1 1
+# 0x93 = 1 0 0 1   0 0 1 1 - v3,v4 board
 # 0x17 = 0 0 0 1   0 0 1 1 - v1,v2 board
 # 0x17 = 0 0 0 1   0 1 1 1 - default
 #        ^ ^ ^ ^   ^ \+/ ^
@@ -295,7 +299,7 @@ AVRDUDE_FLAGS += -B 8
 #        +-------------------- OCDEN (Enable OCD)
 #
 # Fuse low byte (0=enable,1=disable):
-# 0xD7 = 1 1 0 1   0 1 1 1 - v3 board
+# 0xD7 = 1 1 0 1   0 1 1 1 - v3,v4 board
 # 0xE6 = 1 1 1 0   0 1 1 0 - v1,v2 board
 # 0x62 = 0 1 1 0   0 0 1 0 - default
 #        ^ ^ \+/   \--+--/
diff --git a/ports/bdk-atxx4-mstp/spi-master.c b/ports/bdk-atxx4-mstp/spi-master.c
new file mode 100644
index 00000000..ec4931e8
--- /dev/null
+++ b/ports/bdk-atxx4-mstp/spi-master.c
@@ -0,0 +1,64 @@
+/**************************************************************************
+*
+* Copyright (C) 2009 Steve Karg <skarg@users.sourceforge.net>
+*
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to deal in the Software without restriction, including
+* without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to
+* permit persons to whom the Software is furnished to do so, subject to
+* the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*********************************************************************/
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include "hardware.h"
+#include "spi-master.h"
+
+void spi_master_init(void)
+{
+    /* SS, MOSI, MISO, SCK */
+    DDRB=(1<<PINB4)|(1<<PINB5)|(0<<PINB6)|(1<<PINB7);
+    /* Enable SPI, Master, Clk/128 */
+    SPCR=(1<<SPR0)|(1<<SPR1)|(1<<MSTR)|(0<<DORD)|(1<<SPE)|(0<<SPIE);
+    power_spi_enable();
+}
+
+uint8_t spi_master_transfer(
+    uint8_t txdata)
+{
+    /* Send SPI data */
+    SPDR = txdata;
+    /* Wait for transmission complete */
+    while(!(SPSR & (1<<SPIF))) {
+        /* do nothing */
+    }
+
+    return SPDR;
+}
+
+#ifdef TEST_SPI_MASTER
+uint8_t Data_Register;
+int main(void)
+{
+    spi_master_init();
+
+    while(1)
+    {
+        /* loopback test */
+        Data_Register = spi_master_transfer(0xBA);
+    }
+}
+#endif
diff --git a/ports/bdk-atxx4-mstp/spi-master.h b/ports/bdk-atxx4-mstp/spi-master.h
new file mode 100644
index 00000000..45daed8f
--- /dev/null
+++ b/ports/bdk-atxx4-mstp/spi-master.h
@@ -0,0 +1,42 @@
+/**************************************************************************
+*
+* Copyright (C) 2009 Steve Karg <skarg@users.sourceforge.net>
+*
+* Permission is hereby granted, free of charge, to any person obtaining
+* a copy of this software and associated documentation files (the
+* "Software"), to deal in the Software without restriction, including
+* without limitation the rights to use, copy, modify, merge, publish,
+* distribute, sublicense, and/or sell copies of the Software, and to
+* permit persons to whom the Software is furnished to do so, subject to
+* the following conditions:
+*
+* The above copyright notice and this permission notice shall be included
+* in all copies or substantial portions of the Software.
+*
+* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+*********************************************************************/
+#ifndef SPI_MASTER_H
+#define SPI_MASTER_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif /* __cplusplus */
+
+    uint8_t spi_master_transfer(
+        uint8_t txdata);
+
+    void spi_master_init(
+        void);
+
+#ifdef __cplusplus
+}
+#endif /* __cplusplus */
+#endif
diff --git a/ports/bdk-atxx4-mstp/test.c b/ports/bdk-atxx4-mstp/test.c
index 34bac742..a517618c 100644
--- a/ports/bdk-atxx4-mstp/test.c
+++ b/ports/bdk-atxx4-mstp/test.c
@@ -16,6 +16,7 @@
 #include "rs485.h"
 #include "bacnet/datalink/dlmstp.h"
 #include "seeprom.h"
+#include "spi-master.h"
 #include "nvdata.h"
 /* me */
 #include "test.h"
@@ -47,6 +48,7 @@ void test_init(void)
 #else
     BIT_SET(DDRB, DDB0);
 #endif
+    spi_master_init();
 }
 
 /**
@@ -194,6 +196,10 @@ void test_task(void)
                     "\r\nMax:%u", (unsigned)dlmstp_max_master());
                 serial_bytes_send((uint8_t *)Send_Buffer, strlen(Send_Buffer));
                 break;
+            case 's':
+                data_register = spi_master_transfer(0xBA);
+                snprintf(Send_Buffer, sizeof(Send_Buffer), "\r\nSPI:%02Xh", data_register);
+                break;
             default:
                 break;
         }