Attempt to implement working simcard emulator

The BUFLEN is fixed 5 bytes now, which has to be increased.
A timeout has to be implemented, which is smaller than max_waittime.
If the timeout is triggered, the data received in the buffer so far
should be sent to the host computer which is responsible for generating
a response. Without the timeout the max_waittime of the phone would
expire and it would repeat sending the command, so that we do not
have atomary messages anymore.

sam3s_example/simtrace/simtrace.h

@@ -6,7 +6,7 @@
 #define DATAIN      2
 #define INT         3
 
-#define BUFLEN  64
+#define BUFLEN  5
 typedef struct ring_buffer
 {
     uint8_t     buf[BUFLEN*2];   // data buffer