Implement Micheletti P15 scale.

This is pretty similar to the Prix3 code.

Fixes: https://tree.taiga.io/project/stoq/task/1983
Change-Id: Iddd6d776b70b95e4f1262063492004e96ce9ae44

stoqdrivers/scales/base.py

@@ -49,7 +49,10 @@ def check_interfaces(self):
 def get_supported_scales():
     result = {}
 
-    for brand, module_names in [(u'toledo', [u'PrixIII'])]:
+    for brand, module_names in [
+        (u'toledo', [u'PrixIII']),
+        (u'micheletti', [u'MicP15'])
+    ]:
         result[brand] = []
         for module_name in module_names:
             try:

stoqdrivers/scales/micheletti/MicP15.py

@@ -0,0 +1,96 @@
+# -*- Mode: Python; coding: iso-8859-1 -*-
+# vi:si:et:sw=4:sts=4:ts=4
+# Stoqdrivers
+# Copyright (C) 2018 Async Open Source <http://www.async.com.br>
+# All rights reserved
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
+# USA.
+#
+from decimal import Decimal
+
+from zope.interface import implementer
+
+from stoqdrivers.exceptions import InvalidReply
+from stoqdrivers.interfaces import IScale, IScaleInfo
+from stoqdrivers.serialbase import SerialBase, SerialPort
+
+STX = 0x02
+ETX = 0x03
+
+PRICE_PRECISION = 2
+QUANTITY_PRECISION = 3
+
+
+@implementer(IScaleInfo)
+class Package:
+    SIZE = 22
+
+    def __init__(self, raw_data):
+        self.code = None
+        self.price_per_kg = None
+        self.total_price = None
+        self.weight = None
+        self._parse(raw_data)
+
+    def _parse(self, data):
+        if not data:
+            return
+        elif ord(data[0]) != STX or len(data) != self.SIZE:
+            raise InvalidReply("Received inconsistent data")
+
+        self.weight = Decimal(data[1:7]) / (10 ** QUANTITY_PRECISION)
+        self.price_per_kg = Decimal(data[8:14]) / (10 ** PRICE_PRECISION)
+        self.total_price = Decimal(data[15:21]) / (10 ** PRICE_PRECISION)
+
+
+@implementer(IScale)
+class MicP15(SerialBase):
+    CMD_PREFIX = "\x05"
+    EOL_DELIMIT = chr(ETX)
+
+    model_name = "Micheletti P15"
+
+    def __init__(self, device, consts=None):
+        SerialBase.__init__(self, device)
+        self._package = None
+
+    def _get_package(self):
+        # PESO, PRECO, TOTAL
+        # b'\x02  0800  99999  79999\x03'
+        reply = self.writeline('')
+
+        # The sum is just because readline (called internally by writeline)
+        # remove the EOL_DELIMIT from the package received and we need send
+        # to Package's constructor the whole data.
+        return Package(reply + MicP15.EOL_DELIMIT)
+
+    #
+    # IScale implementation
+    #
+
+    def read_data(self):
+        return self._get_package()
+
+
+if __name__ == "__main__":
+    port = SerialPort('/dev/ttyS0')
+    r = MicP15(port)
+    data = r.read_data()
+
+    print("WEIGHT:", data.weight)
+    print("PRICE BY KG:", data.price_per_kg)
+    print("TOTAL PRICE:", data.total_price)
+    print("CODE:", data.code)