diff --git a/firmware/Makefile b/firmware/Makefile
index 267084b..785837f 100644
--- a/firmware/Makefile
+++ b/firmware/Makefile
@@ -138,7 +138,7 @@
 C_LOWLEVEL = board_cstartup_gnu.o board_lowlevel.o syscalls.o exceptions.o
 C_LIBLEVEL = spi.o pio.o pmc.o usart.o pio_it.o pio_capture.o uart_console.o iso7816_4.o wdt.o led.o tc.o
 C_CCID = cciddriver.o USBD.o USBDDriver.o USBD_HAL.o USBRequests.o USBDCallbacks.o USBDescriptors.o USBDDriverCallbacks.o
-C_SIMTRACE = simtrace_iso7816.o usb.o ccid.o sniffer.o phone.o mitm.o ringbuffer.o host_communication.o #iso7816_uart.o
+C_SIMTRACE = simtrace_iso7816.o usb.o ccid.o sniffer.o phone.o mitm.o ringbuffer.o host_communication.o iso7816_fidi.o #iso7816_uart.o
 C_APPLEVEL = main.o
 C_OBJECTS  = $(C_CMSIS) $(C_LOWLEVEL) $(C_LIBLEVEL) $(C_APPLEVEL) $(C_CCID) $(C_SIMTRACE)
 
diff --git a/firmware/src_simtrace/iso7816_fidi.c b/firmware/src_simtrace/iso7816_fidi.c
new file mode 100644
index 0000000..052654c
--- /dev/null
+++ b/firmware/src_simtrace/iso7816_fidi.c
@@ -0,0 +1,65 @@
+/* ISO7816-3 Fi/Di tables + computation */
+/* (C) 2010-2015 by Harald Welte <hwelte@hmw-consulting.de>
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <stdint.h>
+#include <errno.h>
+
+#include "iso7816_fidi.h"
+
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+/* Table 7 of ISO 7816-3:2006 */
+static const uint16_t fi_table[] = {
+	372, 372, 558, 744, 1116, 1488, 1860, 0,
+	0, 512, 768, 1024, 1536, 2048, 0, 0
+};
+
+/* Table 8 from ISO 7816-3:2006 */
+static const uint8_t di_table[] = {
+	0, 1, 2, 4, 8, 16, 32, 64,
+	12, 20, 2, 4, 8, 16, 32, 64,
+};
+
+/* compute the F/D ratio based on Fi and Di values */
+int compute_fidi_ratio(uint8_t fi, uint8_t di)
+{
+	uint16_t f, d;
+	int ret;
+
+	if (fi >= ARRAY_SIZE(fi_table) ||
+	    di >= ARRAY_SIZE(di_table))
+		return -EINVAL;
+
+	f = fi_table[fi];
+	if (f == 0)
+		return -EINVAL;
+
+	d = di_table[di];
+	if (d == 0)
+		return -EINVAL;
+
+	/* See table 7 of ISO 7816-3: From 1000 on we divide by 1/d,
+	 * which equals a multiplication by d */
+	if (di < 8)
+		ret = f / d;
+	else
+		ret = f * d;
+
+	return ret;
+}
diff --git a/firmware/src_simtrace/iso7816_fidi.h b/firmware/src_simtrace/iso7816_fidi.h
new file mode 100644
index 0000000..e4690a5
--- /dev/null
+++ b/firmware/src_simtrace/iso7816_fidi.h
@@ -0,0 +1,6 @@
+#pragma once
+
+#include <stdint.h>
+
+/* compute the F/D ratio based on Fi and Di values */
+int compute_fidi_ratio(uint8_t fi, uint8_t di);
diff --git a/firmware/src_simtrace/simtrace_iso7816.c b/firmware/src_simtrace/simtrace_iso7816.c
index 086cd32..5325bba 100644
--- a/firmware/src_simtrace/simtrace_iso7816.c
+++ b/firmware/src_simtrace/simtrace_iso7816.c
@@ -32,6 +32,7 @@
  *------------------------------------------------------------------------------*/
 
 #include "board.h"
+#include "iso7816_fidi.h"
 
 #include <string.h>
 #include <errno.h>
@@ -109,46 +110,6 @@
 }
 
 /*  FIDI update functions   */
-#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
-
-/* Table 6 from ISO 7816-3 */
-static const uint16_t fi_table[] = {
-	0, 372, 558, 744, 1116, 1488, 1860, 0,
-	0, 512, 768, 1024, 1536, 2048, 0, 0
-};
-
-/* Table 7 from ISO 7816-3 */
-static const uint8_t di_table[] = {
-	0, 1, 2, 4, 8, 16, 0, 0,
-	0, 0, 2, 4, 8, 16, 32, 64,
-};
-
-/* compute the F/D ratio based on Fi and Di values */
-static int compute_fidi_ratio(uint8_t fi, uint8_t di)
-{
-	uint16_t f, d;
-	int ret;
-
-	if (fi >= ARRAY_SIZE(fi_table) ||
-	    di >= ARRAY_SIZE(di_table))
-		return -EINVAL;
-
-	f = fi_table[fi];
-	if (f == 0)
-		return -EINVAL;
-
-	d = di_table[di];
-	if (d == 0)
-		return -EINVAL;
-
-	if (di < 8) 
-		ret = f / d;
-	else
-		ret = f * d;
-
-	return ret;
-}
-
 void update_fidi(uint8_t fidi)
 {
 	int rc;