A brief description of the protocol

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+Arexx Data Logger Protocol
+~~~~~~~~~~~~~~~~~~~~~~~~~~
+All packets have fixed size of 64 bytes. The first byte is a packet
+type, followed by type-dependent data.
+
+Timestamps are 32-bit integers representing the number of seconds
+since 2000-01-01 00:00:00 UTC.
+
+Request packets  (from the PC to the logger)
+~~~~~~~~~~~~~~~
+
+type 03                Request sensor data
+               The data part is probably unused.
+
+type 04                Set clock
+               Data:   u32le   timestamp
+
+
+Reply packets  (from the logger to the PC)
+~~~~~~~~~~~~~
+
+type 00                Report sensor data
+               The data part is a sequence of tuples, each tuple
+               starts with its length.
+
+               9-byte tuples:
+                       u8      tuple length (0x09)
+                       u16le   sensor ID
+                       u16be!  raw value
+                       u32le   timestamp
+
+               10-byte tuples contain one extra byte:
+                       u8      signal quality (units unknown)
+
+               A 0-byte tuple serves as a terminator.