diff --git a/cmdline/read-temp.c b/cmdline/read-temp.c
index c6aa9e7..9567b7c 100644
--- a/cmdline/read-temp.c
+++ b/cmdline/read-temp.c
@@ -106,12 +106,13 @@ int                 cnt, vid, pid;
 		if(cnt < 0){
 			fprintf(stderr, "\nUSB error in iteration %d: %s\n", i, usb_strerror());
 		}
-		rxValue = ((int)buffer[1] & 0xff) | (((int)buffer[0] & 0xff) << 8);
-		rxIndex = ((int)buffer[3] & 0xff) | (((int)buffer[2] & 0xff) << 8);
+		rxIndex = ((int)buffer[1] & 0xff) | (((int)buffer[0] & 0xff) << 8);
 		
 		fprintf(stderr, "request = 0x%04x\n", opcode);
-		fprintf(stderr, "rxValue = 0x%04x value = 0x%04x\n", rxValue, addr);
-		fprintf(stderr, "rxIndex = 0x%04x index = 0x%04x\n", rxIndex, value);	  
+//		fprintf(stderr, "answer: opcode=0x%02x addr=0x%02x value=0x%04x (%i)\n", buffer[1],buffer[0],rxIndex,rxIndex);
+		fprintf(stderr, "answer: value=0x%04x (%i)\n", rxIndex,rxIndex);
+//		fprintf(stderr, "rxValue = 0x%04x value = 0x%04x\n", rxValue, addr);
+//		fprintf(stderr, "rxIndex = 0x%04x index = 0x%04x\n", rxIndex, value);	  
     } else {
 		usage();
 	}
diff --git a/firmware/masterchip/usb.c b/firmware/masterchip/usb.c
index a6cd43c..12f6682 100644
--- a/firmware/masterchip/usb.c
+++ b/firmware/masterchip/usb.c
@@ -10,6 +10,7 @@
 usbMsgLen_t usbFunctionSetup(uchar data[8]) {
   usbRequest_t    *rq = (void *)data;
   static uchar    dataBuffer[5];
+  uint16_t recv;
 
   if(rq->bRequest == 100) {
     dataBuffer[0] = (thermoData [0] & 0xff00)>>8;
@@ -26,23 +27,18 @@ usbMsgLen_t usbFunctionSetup(uchar data[8]) {
     usbMsgPtr = dataBuffer;
     return 4;
   } else {
-    uint8_t opcode = (uint8_t)  ((rq->bRequest & 0xff00)>>8);
+    uint8_t opcode = (uint8_t)	  rq->bRequest;
     uint8_t addr =   (uint8_t)    rq->wValue.bytes[0];
     uint8_t valH =   (uint8_t)    rq->wIndex.bytes[0];
     uint8_t valL =   (uint8_t)    rq->wIndex.bytes[1];
 
     uint16_t send = (valH << 8) | valL;
-//    uint16_t recv = spi_master_communicate(opcode, addr, send);
+    uint16_t recv = spi_master_transceive(opcode, addr, send);
     
-    dataBuffer[0] = opcode;
-    dataBuffer[1] = addr;
-    dataBuffer[2] = valH;
-    dataBuffer[3] = valL;
-    spi_mst_start_packet();
-    spi_mst_write_read(5,dataBuffer);
-    spi_mst_end_packet();
-    usbMsgPtr = dataBuffer+1;
-    return 4;
+	dataBuffer[0] = (recv & 0xff00) >> 8;
+	dataBuffer[1] = (recv & 0xff);
+    usbMsgPtr = dataBuffer;
+    return 2;
     
   }
 
diff --git a/firmware/shared/spi.c b/firmware/shared/spi.c
index 49547f6..45a4204 100644
--- a/firmware/shared/spi.c
+++ b/firmware/shared/spi.c
@@ -126,24 +126,15 @@ void spi_mst_write_read(uint8_t len, uint8_t *data){
 void spi_sla_handle_packet(){
         // TODO: make slave not hangup in case of partial read
 	uint8_t opcode, addr, do_write;
-	uint16_t data;
-    opcode = readbuf[0];
-    addr = readbuf[1];
-	do_write = spi_proto_needswrite(opcode);
-	if(do_write){
-		data = spi_proto_handlewrite(opcode, addr);
-        writebuf[0]=opcode;
-        writebuf[1]=addr;
-        writebuf[2]=(data>>8)&0xff;
-        writebuf[3]=(data)&0xff;
-	} else {
-        writebuf[0]=0;
-        writebuf[1]=2;
-        writebuf[2]=4;
-        writebuf[3]=6;
-        data = (readbuf[3]<<8)&0xff | readbuf[4];
-		spi_proto_handleread(opcode, addr, data);
-	}
+	uint16_t data, newdata;
+    opcode = readbuf[1];
+    addr = readbuf[2];
+	data = (readbuf[3]<<8)&0xff | readbuf[4];
+	newdata = spi_proto_slaveaction(opcode, addr, data);
+	writebuf[0]=opcode;
+	writebuf[1]=addr;
+	writebuf[2]=(newdata>>8)&0xff;
+	writebuf[3]=(newdata)&0xff;
 }
 
 
diff --git a/firmware/shared/spi.h b/firmware/shared/spi.h
index 51e7290..ad91bb2 100644
--- a/firmware/shared/spi.h
+++ b/firmware/shared/spi.h
@@ -22,6 +22,7 @@ void spi_mst_start_packet();
 void spi_mst_end_packet();
 void spi_mst_write(uint8_t len, uint8_t *data);
 void spi_mst_read(uint8_t len, uint8_t *data);
+void spi_mst_write_read(uint8_t len, uint8_t *data);
 void spi_sla_handle_packet();
 
 
diff --git a/firmware/shared/spi_proto.c b/firmware/shared/spi_proto.c
index 16e8ad5..3496540 100644
--- a/firmware/shared/spi_proto.c
+++ b/firmware/shared/spi_proto.c
@@ -3,88 +3,51 @@
 
 /***** MASTER *****/
 
-uint8_t read_data[2];
-uint8_t write_data[4];
+uint8_t mst_buf[5];
 
-void talk_to_slave(uint8_t opcode, uint8_t addr, uint8_t flags)
+uint16_t spi_master_transceive(uint8_t opcode, uint8_t addr, uint16_t value)
 {
-	write_data[0] = opcode;
-	write_data[1] = addr;
-	spi_mst_start_packet();
-	spi_mst_write(flags & SPI_WRITE_DATA? 4 : 3, write_data);
-	spi_mst_read(flags & SPI_READ_DATA? 2 : 0, read_data);
-	spi_mst_end_packet();
-}
-
-uint16_t spi_master_communicate(uint8_t opcode, uint8_t addr, uint16_t value)
-{
-    uint8_t flags = spi_proto_needs(opcode);
-	write_data[0] = opcode;
-	write_data[1] = addr;
-	write_data[2] = value >> 8;
-	write_data[3] = value & 0xff;
-    spi_mst_start_packet();
-	spi_mst_write_read(4,write_data);
-    spi_mst_end_packet();
-    while(write_data[0] == 0){
-        spi_mst_start_packet();
-        spi_mst_write_read(4,write_data);
-        spi_mst_end_packet();
-    }
-	return (write_data[2] << 8) | read_data[3];
-}
-
-uint8_t spi_proto_needs(uint8_t opcode)
-{
-	uint8_t r = SPI_NONE;
-	switch(opcode)
-	{
-		case 1: case 2: case 3:
-			r = SPI_READ_DATA;
-			break;
-		case 4: case 5:
-			r = SPI_WRITE_DATA;
-			break;
-	}
-	return r;
+	do{
+		mst_buf[0] = opcode;
+		mst_buf[1] = addr;
+		mst_buf[2] = value >> 8;
+		mst_buf[3] = value & 0xff;
+		mst_buf[4] = 0; // additional 0 to read the last byte from the slave
+		spi_mst_start_packet();
+		spi_mst_write_read(5,mst_buf);
+		spi_mst_end_packet();
+	} while(mst_buf[1] == 0); // wait for echoed opcode
+
+	// bytes from slave are received shifted right by one
+	return (mst_buf[3] << 8) | mst_buf[4];
 }
 
 
 uint16_t read_temperature(uint8_t number)
 {
-	talk_to_slave(1, number, SPI_READ_DATA);
-	return (read_data[0] << 8) | read_data[1];
+	return 0;
 }
 
 uint8_t read_var8(uint8_t number)
 {
-	talk_to_slave(2, number, SPI_READ_DATA);
-	return read_data[1];
+	return 0;
 }
 
 uint16_t read_var16(uint8_t number)
 {
-	talk_to_slave(3, number, SPI_READ_DATA);
-	return (read_data[0] << 8) | read_data[1];
+	return 0;
 }
 
 void write_var8(uint8_t number, uint8_t value)
 {
-	write_data[2] = 0;
-	write_data[3] = number;
-	talk_to_slave(4, number, SPI_WRITE_DATA);
 }
 
 void write_var16(uint8_t number, uint16_t value)
 {
-	write_data[2] = value >> 8;
-	write_data[3] = value & 0xff;
-	talk_to_slave(5, number, SPI_WRITE_DATA);
 }
 
 void call_func(uint8_t number)
 {
-	talk_to_slave(6, number, SPI_NONE);
 }
 
 
@@ -92,33 +55,33 @@ void call_func(uint8_t number)
 /***** SLAVE *****/
 
 
-uint8_t spi_proto_needswrite(uint8_t opcode) {
-  if(opcode == 4 || opcode == 5) return 0;
-  return 1;
-}
-
-uint16_t spi_proto_handlewrite(uint8_t opcode, uint8_t addr) {
-  if(opcode == 4) {
-    return (uint16_t) (*spi_proto_globals8[addr]);
-  } else if(opcode == 5) {
-    return (*spi_proto_globals16[addr]);
-  } else {
-      return 0xFeFe;
-  }
-
-}
-
-void spi_proto_handleread(uint8_t opcode, uint8_t addr, uint16_t data) {
-  if(opcode == 2) {
-    *spi_proto_globals8[addr] = (uint8_t) data;
-  } else if(opcode == 3) {
-    *spi_proto_globals16[addr] = data;
-  } else if (opcode == 6) {
-    funptr_t func = spi_proto_funcs[addr];
-    (*func)();
-  } else {
-    // boom
-  }
+uint16_t spi_proto_slaveaction(uint8_t opcode, uint8_t addr, uint16_t data) {
+	uint16_t retval = 0;
+	switch(opcode){
+		case 0:
+			retval = data;
+			break;
+		case 1:
+			//TODO
+			retval = 0;
+			break;
+		case 2:
+			retval = (*spi_proto_globals8[addr]);
+			break;
+		case 3:
+			retval = (*spi_proto_globals16[addr]);
+			break;
+		case 4:
+			(*spi_proto_globals8[addr]) = data;
+			break;
+		case 5:
+			(*spi_proto_globals16[addr]) = data;
+			break;
+		case 6:
+			(*spi_proto_funcs[addr])();
+			break;
+	}
+	return retval;
 }
 
 /***** SLAVE END *****/
diff --git a/firmware/shared/spi_proto.h b/firmware/shared/spi_proto.h
index 1d08792..e410236 100644
--- a/firmware/shared/spi_proto.h
+++ b/firmware/shared/spi_proto.h
@@ -9,9 +9,8 @@
 #define SPI_READ_DATA 0x10
 #define SPI_NONE 0
 
-uint16_t spi_master_communicate(uint8_t opcode, uint8_t address, uint16_t value);
+uint16_t spi_master_transceive(uint8_t opcode, uint8_t address, uint16_t value);
 
-uint8_t spi_proto_needs(uint8_t opcode);
 
 uint16_t read_temperature(uint8_t number);
 uint8_t read_var8(uint8_t number);
@@ -30,9 +29,7 @@ extern funptr_t spi_proto_funcs[];
 */
 #include "spi_pointers.h"
 
-uint8_t spi_proto_needswrite(uint8_t opcode);
-uint16_t spi_proto_handlewrite(uint8_t opcode, uint8_t addr);
-void spi_proto_handleread(uint8_t opcode, uint8_t addr, uint16_t data);
+uint16_t spi_proto_slaveaction(uint8_t opcode, uint8_t addr, uint16_t data);
 
 /***** SLAVE END *****/