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
26 [{'ss': bit start sample number,
27 'se': bit end sample number,
32 Since address and word size are variable, a list of all bits in each packet
33 need to be output. Since Microwire is a synchronous protocol with separate
34 input and output lines (SI and SO) they are provided together, but because
35 Microwire is half-duplex only the SI or SO bits will be considered at once.
36 To be able to annotate correctly the instructions formed by the bit, the start
37 and end sample number of each bit (pair of SI/SO bit) are provided.
40 class Decoder(srd.Decoder):
44 longname = 'Microwire'
45 desc = '3-wire, half-duplex, synchronous serial bus.'
48 outputs = ['microwire']
50 {'id': 'cs', 'name': 'CS', 'desc': 'Chip select'},
51 {'id': 'sk', 'name': 'SK', 'desc': 'Clock'},
52 {'id': 'si', 'name': 'SI', 'desc': 'Slave in'},
53 {'id': 'so', 'name': 'SO', 'desc': 'Slave out'},
56 ('start-bit', 'Start bit'),
59 ('status-check-ready', 'Status check ready'),
60 ('status-check-busy', 'Status check busy'),
61 ('warning', 'Warning'),
64 ('si-bits', 'SI bits', (0, 1)),
65 ('so-bits', 'SO bits', (2,)),
66 ('status', 'Status', (3, 4)),
67 ('warnings', 'Warnings', (5,)),
71 self.out_python = self.register(srd.OUTPUT_PYTHON)
72 self.out_ann = self.register(srd.OUTPUT_ANN)
76 # Wait for slave to be selected on rising CS.
77 cs, sk, si, so = self.wait({0: 'r'})
79 self.put(self.samplenum, self.samplenum, self.out_ann,
80 [5, ['Clock should be low on start',
81 'Clock high on start', 'Clock high', 'SK high']])
82 sk = 0 # Enforce correct state for correct clock handling.
83 # Because we don't know if this is bit communication or a
84 # status check we have to collect the SI and SO values on SK
85 # edges while the chip is selected and figure out afterwards.
89 packet.append({'samplenum': self.samplenum,
90 'matched': self.matched,
91 'cs': cs, 'sk': sk, 'si': si, 'so': so})
93 cs, sk, si, so = self.wait([{0: 'l'}, {1: 'r'}, {3: 'e'}])
95 cs, sk, si, so = self.wait([{0: 'l'}, {1: 'f'}, {3: 'e'}])
97 packet.append({'samplenum': self.samplenum,
98 'matched': self.matched,
99 'cs': cs, 'sk': sk, 'si': si, 'so': so})
101 # Figure out if this is a status check.
102 # Either there is no clock or no start bit (on first rising edge).
104 for change in packet:
105 # Get first clock rising edge.
106 if len(change['matched']) > 1 and change['matched'][1] \
112 # The packet is for a status check.
113 # SO low = busy, SO high = ready.
114 # The SO signal might be noisy in the beginning because it starts
117 start_samplenum = packet[0]['samplenum']
118 bit_so = packet[0]['so']
119 # Check for SO edges.
120 for change in packet:
121 if len(change['matched']) > 2 and change['matched'][2]:
122 if bit_so == 0 and change['so']:
123 # Rising edge Busy -> Ready.
124 self.put(start_samplenum, change['samplenum'],
125 self.out_ann, [4, ['Busy', 'B']])
126 start_samplenum = change['samplenum']
127 bit_so = change['so']
130 self.put(start_samplenum, packet[-1]['samplenum'],
131 self.out_ann, [4, ['Busy', 'B']])
133 self.put(start_samplenum, packet[-1]['samplenum'],
134 self.out_ann, [3, ['Ready', 'R']])
137 # Since the slave samples SI on clock rising edge we do the
138 # same. Because the slave changes SO on clock rising edge we
139 # sample on the falling edge.
140 bit_start = 0 # Rising clock sample of bit start.
141 bit_si = 0 # SI value at rising clock edge.
142 bit_so = 0 # SO value at falling clock edge.
143 start_bit = True # Start bit incoming (first bit).
144 python_output = [] # Python output data.
145 for change in packet:
146 if len(change['matched']) > 1 and change['matched'][1]:
148 if change['sk']: # Rising clock edge.
149 if bit_start > 0: # Bit completed.
151 if bit_si == 0: # Start bit missing.
152 self.put(bit_start, change['samplenum'],
154 [5, ['Start bit not high',
157 self.put(bit_start, change['samplenum'],
159 [0, ['Start bit', 'S']])
162 self.put(bit_start, change['samplenum'],
164 [1, ['SI bit: %d' % bit_si,
167 self.put(bit_start, change['samplenum'],
169 [2, ['SO bit: %d' % bit_so,
172 python_output.append({'ss': bit_start,
173 'se': change['samplenum'],
174 'si': bit_si, 'so': 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 python_output.append({'ss': bit_start,
189 'se': change['samplenum'],
190 'si': bit_si, 'so': bit_so})
191 self.put(packet[0]['samplenum'],
192 packet[len(packet) - 1]['samplenum'],
193 self.out_python, python_output)