2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz>
5 ## Copyright (C) 2012-2013 Uwe Hermann <uwe@hermann-uwe.de>
7 ## This program is free software; you can redistribute it and/or modify
8 ## it under the terms of the GNU General Public License as published by
9 ## the Free Software Foundation; either version 2 of the License, or
10 ## (at your option) any later version.
12 ## This program is distributed in the hope that it will be useful,
13 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
14 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 ## GNU General Public License for more details.
17 ## You should have received a copy of the GNU General Public License
18 ## along with this program; if not, write to the Free Software
19 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 # SPI protocol decoder
24 import sigrokdecode as srd
26 # Key: (CPOL, CPHA). Value: SPI mode.
27 # Clock polarity (CPOL) = 0/1: Clock is low/high when inactive.
28 # Clock phase (CPHA) = 0/1: Data is valid on the leading/trailing clock edge.
36 class Decoder(srd.Decoder):
40 longname = 'Serial Peripheral Interface'
41 desc = 'Full-duplex, synchronous, serial bus.'
46 {'id': 'miso', 'name': 'MISO',
47 'desc': 'SPI MISO line (Master in, slave out)'},
48 {'id': 'mosi', 'name': 'MOSI',
49 'desc': 'SPI MOSI line (Master out, slave in)'},
50 {'id': 'sck', 'name': 'CLK', 'desc': 'SPI clock line'},
51 {'id': 'cs', 'name': 'CS#', 'desc': 'SPI CS (chip select) line'},
53 optional_probes = [] # TODO
55 'cs_polarity': ['CS# polarity', 'active-low'],
56 'cpol': ['Clock polarity', 0],
57 'cpha': ['Clock phase', 0],
58 'bitorder': ['Bit order within the SPI data', 'msb-first'],
59 'wordsize': ['Word size of SPI data', 8], # 1-64?
60 'format': ['Data format', 'hex'],
63 ['MISO/MOSI data', 'MISO/MOSI SPI data'],
64 ['MISO data', 'MISO SPI data'],
65 ['MOSI data', 'MOSI SPI data'],
66 ['Warnings', 'Human-readable warnings'],
74 self.bytesreceived = 0
77 self.cs_was_deasserted_during_data_word = 0
82 def start(self, metadata):
83 self.out_proto = self.add(srd.OUTPUT_PROTO, 'spi')
84 self.out_ann = self.add(srd.OUTPUT_ANN, 'spi')
87 return 'SPI: %d bytes received' % self.bytesreceived
89 def putpw(self, data):
90 self.put(self.startsample, self.samplenum, self.out_proto, data)
93 self.put(self.startsample, self.samplenum, self.out_ann, data)
95 def handle_bit(self, miso, mosi, sck, cs):
96 # If this is the first bit, save its sample number.
97 if self.bitcount == 0:
98 self.startsample = self.samplenum
99 active_low = (self.options['cs_polarity'] == 'active-low')
100 deasserted = cs if active_low else not cs
102 self.cs_was_deasserted_during_data_word = 1
104 ws = self.options['wordsize']
106 # Receive MOSI bit into our shift register.
107 if self.options['bitorder'] == 'msb-first':
108 self.mosidata |= mosi << (ws - 1 - self.bitcount)
110 self.mosidata |= mosi << self.bitcount
112 # Receive MISO bit into our shift register.
113 if self.options['bitorder'] == 'msb-first':
114 self.misodata |= miso << (ws - 1 - self.bitcount)
116 self.misodata |= miso << self.bitcount
120 # Continue to receive if not enough bits were received, yet.
121 if self.bitcount != ws:
124 self.putpw(['DATA', self.mosidata, self.misodata])
125 self.putw([0, ['%02X/%02X' % (self.mosidata, self.misodata)]])
126 self.putw([1, ['%02X' % self.misodata]])
127 self.putw([2, ['%02X' % self.mosidata]])
129 if self.cs_was_deasserted_during_data_word:
130 self.putw([3, ['CS# was deasserted during this data word!']])
132 # Reset decoder state.
137 # Keep stats for summary.
138 self.bytesreceived += 1
140 def find_clk_edge(self, miso, mosi, sck, cs):
142 # Send all CS# pin value changes.
143 self.put(self.samplenum, self.samplenum, self.out_proto,
144 ['CS-CHANGE', self.oldcs, cs])
147 # Ignore sample if the clock pin hasn't changed.
148 if sck == self.oldsck:
153 # Sample data on rising/falling clock edge (depends on mode).
154 mode = spi_mode[self.options['cpol'], self.options['cpha']]
155 if mode == 0 and sck == 0: # Sample on rising clock edge
157 elif mode == 1 and sck == 1: # Sample on falling clock edge
159 elif mode == 2 and sck == 1: # Sample on falling clock edge
161 elif mode == 3 and sck == 0: # Sample on rising clock edge
164 # Found the correct clock edge, now get the SPI bit(s).
165 self.handle_bit(miso, mosi, sck, cs)
167 def decode(self, ss, es, data):
168 # TODO: Either MISO or MOSI could be optional. CS# is optional.
169 for (self.samplenum, pins) in data:
171 # Ignore identical samples early on (for performance reasons).
172 if self.oldpins == pins:
174 self.oldpins, (miso, mosi, sck, cs) = pins, pins
177 if self.state == 'IDLE':
178 self.find_clk_edge(miso, mosi, sck, cs)
180 raise Exception('Invalid state: %s' % self.state)