2 ## This file is part of the sigrok project.
4 ## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
6 ## This program is free software; you can redistribute it and/or modify
7 ## it under the terms of the GNU General Public License as published by
8 ## the Free Software Foundation; either version 2 of the License, or
9 ## (at your option) any later version.
11 ## This program is distributed in the hope that it will be useful,
12 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 ## GNU General Public License for more details.
16 ## You should have received a copy of the GNU General Public License
17 ## along with this program; if not, write to the Free Software
18 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 # Generic I2C demultiplexing protocol decoder
24 # Takes an I2C stream as input and outputs multiple I2C streams, each stream
25 # containing only I2C packets for one specific I2C slave.
28 import sigrokdecode as srd
30 class Decoder(srd.Decoder):
34 longname = 'Generic I2C demultiplexer'
39 outputs = [] # TODO: Only known at run-time.
45 def __init__(self, **kwargs):
46 self.packets = [] # Local cache of I2C packets
47 self.slaves = [] # List of known slave addresses
48 self.stream = -1 # Current output stream
49 self.streamcount = 0 # Number of created output streams
51 def start(self, metadata):
57 # Grab I2C packets into a local cache, until an I2C STOP condition
58 # packet comes along. At some point before that STOP condition, there
59 # will have been an ADDRESS READ or ADDRESS WRITE which contains the
60 # I2C address of the slave that the master wants to talk to.
61 # We use this slave address to figure out which output stream should
62 # get the whole chunk of packets (from START to STOP).
63 def decode(self, ss, es, data):
65 cmd, databyte, ack = data
67 # Add the I2C packet to our local cache.
68 self.packets += [[ss, es, data]]
70 if cmd in ('ADDRESS READ', 'ADDRESS WRITE'):
71 if databyte in self.slaves:
72 self.stream = self.slaves.index(databyte)
75 # We're never seen this slave, add a new stream.
76 self.slaves += [databyte]
77 self.out_proto += [self.add(srd.OUTPUT_PROTO,
78 'i2c-%s' % hex(databyte))]
79 self.stream = self.streamcount
83 raise Exception('Invalid stream!') # FIXME?
85 # Send the whole chunk of I2C packets to the correct stream.
86 for p in self.packets:
87 self.put(p[0], p[1], self.out_proto[self.stream], p[2])
92 pass # Do nothing, only add the I2C packet to our cache.