pyzephyr is a Python library for interfacing with a Zephyr BioHarness(TM) device
over a serial Bluetooth connection.

The following things are supported:
 - Reading the data stream from the device and sending command messages to
   the device (zephyr.protocol.Protocol)
 - Parsing data messages from a serial stream (zephyr.message.MessageFrameParser)
 - Extracting signal values from signal packets (zephyr.signal.SignalMessageParser)
 - Collecting continuous and timestamped signal streams (zephyr.signal.SignalCollector)
 - Extracting R-to-R ECG events (zephyr.rr_event.SignalCollectorWithRRProcessing)
 - A continuous stream of signal values with a constant delay, which hides the
   packet representation of the signals (zephyr.delayed_stream.DelayedRealTimeStream)


The typical flow of
 - data from the device to pyzephyr and
 - commands from pyzephyr to the device

is shown below.


  |--------------------------------------------------------|
  |                     Serial connection                  |
  |--------------------------------------------------------|
              |                               ^
              |                               |
              v                               |          
  |-----------------------|       |------------------------|
  |   Bytes from device   |       |     Bytes to device    |
  |-----------------------|       |------------------------|
              |                               ^
              |                               |
              v                               |
  |--------------------------------------------------------|
  |                          Protocol                      |
  |--------------------------------------------------------|
              |                               ^
              |                               |
              v                               |          
  |-----------------------|       |------------------------|
  |  MessageFrameParser   |       | Commands to the device |
  |-----------------------|       |------------------------|
              |
              |
              v
  |-----------------------|
  |    SignalCollector    |
  |-----------------------|
              |
              |
              v
  |-----------------------|
  | DelayedRealTimeStream |
  |-----------------------|
              |
              |
              v
  |-----------------------|
  |  A continuous stream  |
  |   of signal values    |
  |-----------------------|