Sometimes there are a few garbages bytes received before the preamble
bytes. This typically happens when trying to download again after a
failed attempt. However trying to flush them immediately after opening
the serial port doesn't work.
When the OSTC receives the download dives command, it responds
immediately with the preamble bytes. But then it does a linear search
through its internal memory to locate the end-of-profile marker. As a
result the response time increases when the marker is located near the
end of the memory area. In the worst case scenario, the response time
can exceed the 3 second read timeout with a few milliseconds.
Since the required timeout depends on the total amount of profile
memory, this problem was indirectly introduced with firmware v1.91,
which doubled the amount of profile memory from 32K to 64K.
