diff --git a/firmware/masterchip/spi_config.h b/firmware/masterchip/spi_config.h
new file mode 100644
index 0000000..30e155c
--- /dev/null
+++ b/firmware/masterchip/spi_config.h
@@ -0,0 +1,7 @@
+
+#define SPI_BAUDRATE 1000000
+#ifdef SPI_MASTER
+#undef SPI_MASTER
+#endif //SPI_MASTER
+//#define SPI_SS_PORT D
+//#define SPI_SS_PIN 7
diff --git a/firmware/shared/spi.c b/firmware/shared/spi.c
index e2dc977..bcf42c8 100644
--- a/firmware/shared/spi.c
+++ b/firmware/shared/spi.c
@@ -1,8 +1,12 @@
 #include <avr/io.h>
 #include <stdint.h>
 #include <math.h>
+#include <avr/interrupt.h>
+
+
 #include "main.h"
 
+
 #include <spi.h>
 
 uint16_t *spi_proto_globals8[] = {
@@ -80,6 +84,10 @@ void spi_init(){
 #endif		
 	SPSR = spsr;
 	SPCR = spcr;
+
+#ifndef SPI_MASTER
+    SPCR |= _BV(SPIE); //enable interrupts
+#endif
 }
 
 
@@ -114,7 +122,7 @@ void spi_mst_read(uint8_t len, uint8_t *data){
 
 
 
-void spi_sla_handle_packet(){
+void __attribute__((always_inline)) spi_sla_handle_packet(){
         // TODO: make slave not hangup in case of partial read
 	uint8_t opcode, addr, do_write;
 	uint16_t data;
@@ -141,7 +149,13 @@ void spi_sla_handle_packet(){
 	}
 }
 
-
+#ifndef SPI_MASTER
+ISR(SPI_vect){
+    SPCR &= ~(_BV(SPIE)); //disable spi interrupts
+    spi_sla_handle_packet(); 
+    SPCR |= _BV(SPIE);
+}
+#endif //not SPI_MASTER
 	
 
 	
diff --git a/firmware/shared/spi.h b/firmware/shared/spi.h
index f862524..51e7290 100644
--- a/firmware/shared/spi.h
+++ b/firmware/shared/spi.h
@@ -3,12 +3,7 @@
 
 #include "spi_proto.h"
 
-#define SPI_BAUDRATE 1000000
-#define SPI_MASTER 1
-#define SPI_READBUF_LEN 32
-#define SPI_SS_PORT D
-#define SPI_SS_PIN 7
-
+#include "spi_config.h"
 
 
 // copied/adapted from usbdrv.h
diff --git a/firmware/slavechip/Makefile b/firmware/slavechip/Makefile
index aef3d40..c59e510 100644
--- a/firmware/slavechip/Makefile
+++ b/firmware/slavechip/Makefile
@@ -24,7 +24,7 @@ flash:	all
 	avrdude -c usbasp -p m88 -U flash:w:firmware.hex
 
 fuses:
-	avrdude -c usbasp -p m88 -U lfuse:w:0xe2:m -U hfuse:w:0xdf:m -U efuse:w:0xf9:m 
+	avrdude -c usbasp -p m88 -U lfuse:w:0xe2:m -U hfuse:w:0xdf:m  
 
 
 ## what are the source dependencies
diff --git a/firmware/slavechip/spi_config.h b/firmware/slavechip/spi_config.h
new file mode 100644
index 0000000..08250e4
--- /dev/null
+++ b/firmware/slavechip/spi_config.h
@@ -0,0 +1,5 @@
+
+#define SPI_BAUDRATE 1000000
+#define SPI_MASTER
+#define SPI_SS_PORT D
+#define SPI_SS_PIN 7