2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2017 Kevin Redon <kingkevin@cuvoodoo.info>
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, see <http://www.gnu.org/licenses/>.
20 import sigrokdecode as srd
21 from collections import namedtuple
27 [namedtuple('ss': bit start sample number,
28 'se': bit end sample number,
33 Since address and word size are variable, a list of all bits in each packet
34 need to be output. Since Microwire is a synchronous protocol with separate
35 input and output lines (SI and SO) they are provided together, but because
36 Microwire is half-duplex only the SI or SO bits will be considered at once.
37 To be able to annotate correctly the instructions formed by the bit, the start
38 and end sample number of each bit (pair of SI/SO bit) are provided.
41 PyPacket = namedtuple('PyPacket', 'ss se si so')
43 class Decoder(srd.Decoder):
47 longname = 'Microwire'
48 desc = '3-wire, half-duplex, synchronous serial bus.'
51 outputs = ['microwire']
53 {'id': 'cs', 'name': 'CS', 'desc': 'Chip select'},
54 {'id': 'sk', 'name': 'SK', 'desc': 'Clock'},
55 {'id': 'si', 'name': 'SI', 'desc': 'Slave in'},
56 {'id': 'so', 'name': 'SO', 'desc': 'Slave out'},
59 ('start-bit', 'Start bit'),
62 ('status-check-ready', 'Status check ready'),
63 ('status-check-busy', 'Status check busy'),
64 ('warning', 'Warning'),
67 ('si-bits', 'SI bits', (0, 1)),
68 ('so-bits', 'SO bits', (2,)),
69 ('status', 'Status', (3, 4)),
70 ('warnings', 'Warnings', (5,)),
74 self.out_python = self.register(srd.OUTPUT_PYTHON)
75 self.out_ann = self.register(srd.OUTPUT_ANN)
79 # Wait for slave to be selected on rising CS.
80 cs, sk, si, so = self.wait({0: 'r'})
82 self.put(self.samplenum, self.samplenum, self.out_ann,
83 [5, ['Clock should be low on start',
84 'Clock high on start', 'Clock high', 'SK high']])
85 sk = 0 # Enforce correct state for correct clock handling.
86 # Because we don't know if this is bit communication or a
87 # status check we have to collect the SI and SO values on SK
88 # edges while the chip is selected and figure out afterwards.
92 packet.append({'samplenum': self.samplenum,
93 'matched': self.matched,
94 'cs': cs, 'sk': sk, 'si': si, 'so': so})
95 edge = 'r' if sk == 0 else 'f'
96 cs, sk, si, so = self.wait([{0: 'l'}, {1: edge}, {3: 'e'}])
98 packet.append({'samplenum': self.samplenum,
99 'matched': self.matched,
100 'cs': cs, 'sk': sk, 'si': si, 'so': so})
102 # Figure out if this is a status check.
103 # Either there is no clock or no start bit (on first rising edge).
105 for change in packet:
106 # Get first clock rising edge.
107 if len(change['matched']) > 1 and change['matched'][1] \
113 # The packet is for a status check.
114 # SO low = busy, SO high = ready.
115 # The SO signal might be noisy in the beginning because it starts
118 start_samplenum = packet[0]['samplenum']
119 bit_so = packet[0]['so']
120 # Check for SO edges.
121 for change in packet:
122 if len(change['matched']) > 2 and change['matched'][2]:
123 if bit_so == 0 and change['so']:
124 # Rising edge Busy -> Ready.
125 self.put(start_samplenum, change['samplenum'],
126 self.out_ann, [4, ['Busy', 'B']])
127 start_samplenum = change['samplenum']
128 bit_so = change['so']
131 self.put(start_samplenum, packet[-1]['samplenum'],
132 self.out_ann, [4, ['Busy', 'B']])
134 self.put(start_samplenum, packet[-1]['samplenum'],
135 self.out_ann, [3, ['Ready', 'R']])
138 # Since the slave samples SI on clock rising edge we do the
139 # same. Because the slave changes SO on clock rising edge we
140 # sample on the falling edge.
141 bit_start = 0 # Rising clock sample of bit start.
142 bit_si = 0 # SI value at rising clock edge.
143 bit_so = 0 # SO value at falling clock edge.
144 start_bit = True # Start bit incoming (first bit).
145 pydata = [] # Python output data.
146 for change in packet:
147 if len(change['matched']) > 1 and change['matched'][1]:
149 if change['sk']: # Rising clock edge.
150 if bit_start > 0: # Bit completed.
152 if bit_si == 0: # Start bit missing.
153 self.put(bit_start, change['samplenum'],
155 [5, ['Start bit not high',
158 self.put(bit_start, change['samplenum'],
160 [0, ['Start bit', 'S']])
163 self.put(bit_start, change['samplenum'],
165 [1, ['SI bit: %d' % bit_si,
168 self.put(bit_start, change['samplenum'],
170 [2, ['SO bit: %d' % bit_so,
173 pydata.append(PyPacket(bit_start,
174 change['samplenum'], bit_si, bit_so))
175 bit_start = change['samplenum']
176 bit_si = change['si']
177 else: # Falling clock edge.
178 bit_so = change['so']
179 elif change['matched'][0] and \
180 change['cs'] == 0 and change['sk'] == 0:
182 self.put(bit_start, change['samplenum'], self.out_ann,
183 [1, ['SI bit: %d' % bit_si,
184 'SI: %d' % bit_si, '%d' % bit_si]])
185 self.put(bit_start, change['samplenum'], self.out_ann,
186 [2, ['SO bit: %d' % bit_so,
187 'SO: %d' % bit_so, '%d' % bit_so]])
188 pydata.append(PyPacket(bit_start, change['samplenum'],
190 self.put(packet[0]['samplenum'],
191 packet[len(packet) - 1]['samplenum'],
192 self.out_python, pydata)