added in micropython external library for const feature.

it's returing valid attribute arrays, that just need converted on z2m
side.

it's also respecting the stop command from the console, which I will
attempt to expose as just a button press.

venv/Lib/site-packages/serial/tools/hexlify_codec.py

@@ -0,0 +1,126 @@
+#! python
+#
+# This is a codec to create and decode hexdumps with spaces between characters. used by miniterm.
+#
+# This file is part of pySerial. https://github.com/pyserial/pyserial
+# (C) 2015-2016 Chris Liechti <cliechti@gmx.net>
+#
+# SPDX-License-Identifier:    BSD-3-Clause
+"""\
+Python 'hex' Codec - 2-digit hex with spaces content transfer encoding.
+
+Encode and decode may be a bit missleading at first sight...
+
+The textual representation is a hex dump: e.g. "40 41"
+The "encoded" data of this is the binary form, e.g. b"@A"
+
+Therefore decoding is binary to text and thus converting binary data to hex dump.
+
+"""
+
+from __future__ import absolute_import
+
+import codecs
+import serial
+
+
+try:
+    unicode
+except (NameError, AttributeError):
+    unicode = str       # for Python 3, pylint: disable=redefined-builtin,invalid-name
+
+
+HEXDIGITS = '0123456789ABCDEF'
+
+
+# Codec APIs
+
+def hex_encode(data, errors='strict'):
+    """'40 41 42' -> b'@ab'"""
+    return (serial.to_bytes([int(h, 16) for h in data.split()]), len(data))
+
+
+def hex_decode(data, errors='strict'):
+    """b'@ab' -> '40 41 42'"""
+    return (unicode(''.join('{:02X} '.format(ord(b)) for b in serial.iterbytes(data))), len(data))
+
+
+class Codec(codecs.Codec):
+    def encode(self, data, errors='strict'):
+        """'40 41 42' -> b'@ab'"""
+        return serial.to_bytes([int(h, 16) for h in data.split()])
+
+    def decode(self, data, errors='strict'):
+        """b'@ab' -> '40 41 42'"""
+        return unicode(''.join('{:02X} '.format(ord(b)) for b in serial.iterbytes(data)))
+
+
+class IncrementalEncoder(codecs.IncrementalEncoder):
+    """Incremental hex encoder"""
+
+    def __init__(self, errors='strict'):
+        self.errors = errors
+        self.state = 0
+
+    def reset(self):
+        self.state = 0
+
+    def getstate(self):
+        return self.state
+
+    def setstate(self, state):
+        self.state = state
+
+    def encode(self, data, final=False):
+        """\
+        Incremental encode, keep track of digits and emit a byte when a pair
+        of hex digits is found. The space is optional unless the error
+        handling is defined to be 'strict'.
+        """
+        state = self.state
+        encoded = []
+        for c in data.upper():
+            if c in HEXDIGITS:
+                z = HEXDIGITS.index(c)
+                if state:
+                    encoded.append(z + (state & 0xf0))
+                    state = 0
+                else:
+                    state = 0x100 + (z << 4)
+            elif c == ' ':      # allow spaces to separate values
+                if state and self.errors == 'strict':
+                    raise UnicodeError('odd number of hex digits')
+                state = 0
+            else:
+                if self.errors == 'strict':
+                    raise UnicodeError('non-hex digit found: {!r}'.format(c))
+        self.state = state
+        return serial.to_bytes(encoded)
+
+
+class IncrementalDecoder(codecs.IncrementalDecoder):
+    """Incremental decoder"""
+    def decode(self, data, final=False):
+        return unicode(''.join('{:02X} '.format(ord(b)) for b in serial.iterbytes(data)))
+
+
+class StreamWriter(Codec, codecs.StreamWriter):
+    """Combination of hexlify codec and StreamWriter"""
+
+
+class StreamReader(Codec, codecs.StreamReader):
+    """Combination of hexlify codec and StreamReader"""
+
+
+def getregentry():
+    """encodings module API"""
+    return codecs.CodecInfo(
+        name='hexlify',
+        encode=hex_encode,
+        decode=hex_decode,
+        incrementalencoder=IncrementalEncoder,
+        incrementaldecoder=IncrementalDecoder,
+        streamwriter=StreamWriter,
+        streamreader=StreamReader,
+        #~ _is_text_encoding=True,
+    )