diff --git a/firmware/include_sam3s/usart.h b/firmware/include_sam3s/usart.h
index 1e4063f3..7f58b50d 100644
--- a/firmware/include_sam3s/usart.h
+++ b/firmware/include_sam3s/usart.h
@@ -97,6 +97,7 @@
 
 typedef struct Usart_info {
     Usart *base;
+    uint8_t state;
     uint32_t id;
 } Usart_info;
 
diff --git a/firmware/src_board/iso7816_4.c b/firmware/src_board/iso7816_4.c
index dcf86d01..59598ca4 100644
--- a/firmware/src_board/iso7816_4.c
+++ b/firmware/src_board/iso7816_4.c
@@ -60,12 +60,10 @@
 /*-----------------------------------------------------------------------------
  *          Internal variables
  *-----------------------------------------------------------------------------*/
-/** Variable for state of send and receive froom USART */
-static uint8_t StateUsartGlobal = USART_RCV;
 /** Pin reset master card */
 static Pin *st_pinIso7816RstMC;
 
-struct Usart_info usart_sim = {.base = USART_SIM, .id = ID_USART_SIM};
+struct Usart_info usart_sim = {.base = USART_SIM, .id = ID_USART_SIM, .state = USART_RCV};
 
 /*----------------------------------------------------------------------------
  *          Internal functions
@@ -84,10 +82,10 @@ uint32_t ISO7816_GetChar( uint8_t *pCharToReceive, Usart_info *usart)
     Usart *us_base = usart->base;
     uint32_t us_id = usart->id;
 
-    if( StateUsartGlobal == USART_SEND ) {
+    if( usart->state == USART_SEND ) {
         while((us_base->US_CSR & US_CSR_TXEMPTY) == 0) {}
         us_base->US_CR = US_CR_RSTSTA | US_CR_RSTIT | US_CR_RSTNACK;
-        StateUsartGlobal = USART_RCV;
+        usart->state = USART_RCV;
     }
 
     /* Wait USART ready for reception */
@@ -133,9 +131,9 @@ uint32_t ISO7816_SendChar( uint8_t CharToSend, Usart_info *usart )
 
     TRACE_DEBUG("***Send char: 0x%X\n\r", CharToSend);
 
-    if( StateUsartGlobal == USART_RCV ) {
+    if( usart->state == USART_RCV ) {
         us_base->US_CR = US_CR_RSTSTA | US_CR_RSTIT | US_CR_RSTNACK;
-        StateUsartGlobal = USART_SEND;
+        usart->state = USART_SEND;
     }
 
     /* Wait USART ready for transmit */
diff --git a/firmware/src_simtrace/ccid.c b/firmware/src_simtrace/ccid.c
index 2a16bd10..2d1959fd 100644
--- a/firmware/src_simtrace/ccid.c
+++ b/firmware/src_simtrace/ccid.c
@@ -59,7 +59,7 @@ static const Pin pinsPower[] = {PWR_PINS};
 static const Pin pinIso7816RstMC  = PIN_ISO7816_RSTMC;
 static uint8_t sim_inserted = 0;
 
-static struct Usart_info usart_info = {.base = USART_SIM, .id = ID_USART_SIM};
+static struct Usart_info usart_info = {.base = USART_SIM, .id = ID_USART_SIM, .state = USART_RCV};
 
 /*------------------------------------------------------------------------------
  *         Optional smartcard detection
diff --git a/firmware/src_simtrace/phone.c b/firmware/src_simtrace/phone.c
index f4f76605..82ba6128 100644
--- a/firmware/src_simtrace/phone.c
+++ b/firmware/src_simtrace/phone.c
@@ -108,7 +108,7 @@ static const Pin pPwr[] = {
 
 static const Pin pinPhoneRST = PIN_ISO7816_RST_PHONE;
 
-static struct Usart_info usart_info = {.base = USART_PHONE, .id = ID_USART_PHONE};
+static struct Usart_info usart_info = {.base = USART_PHONE, .id = ID_USART_PHONE, .state = USART_RCV};
 
 #define PR  TRACE_INFO
 
@@ -123,9 +123,6 @@ static struct Usart_info usart_info = {.base = USART_PHONE, .id = ID_USART_PHONE
 /*-----------------------------------------------------------------------------
  *          Internal variables
  *-----------------------------------------------------------------------------*/
-/** Variable for state of send and receive froom USART */
-static uint8_t StateUsartGlobal = USART_RCV;
-
 static uint8_t host_to_sim_buf[BUFLEN];
 
 /*-----------------------------------------------------------------------------
diff --git a/firmware/src_simtrace/simtrace.h b/firmware/src_simtrace/simtrace.h
index 32c9fc30..83fc8b10 100644
--- a/firmware/src_simtrace/simtrace.h
+++ b/firmware/src_simtrace/simtrace.h
@@ -14,8 +14,16 @@
 #define PHONE_DATAIN      5
 #define PHONE_INT         6
 
-#define CLK_MASTER      1
-#define CLK_SLAVE       0
+#define CLK_MASTER      true
+#define CLK_SLAVE       false
+
+/* ===================================================*/
+/*                      Taken from iso7816_4.c        */
+/* ===================================================*/
+/** Flip flop for send and receive char */
+#define USART_SEND 0
+#define USART_RCV  1
+
 
 extern volatile ringbuf sim_rcv_buf;
 
diff --git a/firmware/src_simtrace/sniffer.c b/firmware/src_simtrace/sniffer.c
index 194d2e89..e0fb520e 100644
--- a/firmware/src_simtrace/sniffer.c
+++ b/firmware/src_simtrace/sniffer.c
@@ -60,7 +60,7 @@ static const Pin pPwr[] = {
     {VCC_FWD, PIOA, ID_PIOA, PIO_OUTPUT_1, PIO_DEFAULT}
 };
 
-static struct Usart_info usart_info = {.base = USART_PHONE, .id = ID_USART_PHONE};
+static struct Usart_info usart_info = {.base = USART_PHONE, .id = ID_USART_PHONE, .state = USART_RCV};
 
 /*-----------------------------------------------------------------------------
  *          Initialization routine