diff --git a/firmware/Makefile.inc b/firmware/Makefile.inc
index db15fd6..ed5e537 100644
--- a/firmware/Makefile.inc
+++ b/firmware/Makefile.inc
@@ -1,4 +1,4 @@
-DEFINES += -DF_CPU=16000000
+#DEFINES += -DF_CPU=16000000
 CFLAGS += -save-temps
 CFLAGS += -std=gnu99 -Wall # implements C99, for <util/atomic.h>
 # this removes dead code and does global linker optimization
diff --git a/firmware/masterchip/Makefile b/firmware/masterchip/Makefile
index 6630a39..f8b9ce8 100644
--- a/firmware/masterchip/Makefile
+++ b/firmware/masterchip/Makefile
@@ -1,6 +1,8 @@
 # masterchip-makefile
 include ../Makefile.inc
 
+DEFINES += -DF_CPU=16000000
+
 COMPILE = avr-gcc $(CFLAGS) $(DEFINES)
 
 OBJECTS = usbdrv/usbdrvasm.o usbdrv/usbdrv.o main.o display.o lcd/lcd.o usb.o softtimer.o spi.o spi_proto.o spi_pointers.o
diff --git a/firmware/slavechip/Makefile b/firmware/slavechip/Makefile
index 29de61e..4ed98fe 100644
--- a/firmware/slavechip/Makefile
+++ b/firmware/slavechip/Makefile
@@ -1,5 +1,6 @@
 include ../Makefile.inc
 
+DEFINES += -DF_CPU=8000000
 COMPILE = avr-gcc $(CFLAGS) $(DEFINES)
 
 OBJECTS = main.o mcp_adc.o i2c_simple.o softtimer.o spi_proto.o spi.o spi_pointers.o muxer.o debug.o
diff --git a/firmware/slavechip/main.c b/firmware/slavechip/main.c
index f403b97..f0fe4da 100644
--- a/firmware/slavechip/main.c
+++ b/firmware/slavechip/main.c
@@ -19,6 +19,8 @@ int16_t temp_avg_count[4];
  * - multiplexer:
  *		C3: inhibit
  *		C0-C2: muxer select
+ *	- offset measurement
+ *	    D0-D3 offset compensation
  *
  *
  * amp 0 is on muxer channel 2
@@ -97,6 +99,8 @@ void hardinit() {
   spi_init();
 
   muxer_init();
+  offset_measure_init();
+  
   i2c_init();
 
   sei();
@@ -138,6 +142,19 @@ int __attribute__((noreturn)) main(void) {
 		}
 	}
 
+	SOFTTIMER(3,4000){
+		static uint8_t toggle;
+		if(toggle){
+			offset_measure_start(0);
+			toggle=0;
+			dbgLog("measuring offset\n");
+		} else {
+			offset_measure_stop();
+			toggle=1;
+			dbgLog("stopping offset-measuring\n");
+		}
+	}
+
   }
 }
 
diff --git a/firmware/slavechip/muxer.c b/firmware/slavechip/muxer.c
index 53fecd4..39c3a3d 100644
--- a/firmware/slavechip/muxer.c
+++ b/firmware/slavechip/muxer.c
@@ -14,3 +14,19 @@ void muxer_set(uint8_t channel){
 	//TODO: delays, check everything, mask in register
 }
 
+
+void offset_measure_init(){
+	DDRD |= 0x0f; // first 4 pins as output
+//	PORTD = 0x00; // turn everything off
+}
+
+void offset_measure_start(uint8_t channel){
+	if(channel >3){
+		return;
+	}
+	PORTD |= (1<<channel);
+}
+
+void offset_measure_stop(){
+	PORTD &= ~0x0f;
+}
diff --git a/firmware/slavechip/muxer.h b/firmware/slavechip/muxer.h
index 82d04b3..7c1b424 100644
--- a/firmware/slavechip/muxer.h
+++ b/firmware/slavechip/muxer.h
@@ -4,3 +4,7 @@
 
 void muxer_init();
 void muxer_set(uint8_t channel);
+
+void offset_measure_init();
+void offset_measure_start(uint8_t channel);
+void offset_measure_stop();