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', 'Status check'),
60 ('warning', 'Warning'),
63 ('si-bits', 'SI bits', (0, 1)),
64 ('so-bits', 'SO bits', (2,)),
65 ('status', 'Status', (3,)),
66 ('warnings', 'Warnings', (4,)),
70 self.out_python = self.register(srd.OUTPUT_PYTHON)
71 self.out_ann = self.register(srd.OUTPUT_ANN)
75 # Wait for slave to be selected on rising CS.
76 cs, sk, si, so = self.wait({0: 'r'})
78 self.put(self.samplenum, self.samplenum, self.out_ann,
79 [4, ['Clock should be low on start',
80 'Clock high on start', 'Clock high', 'SK high']])
81 sk = 0 # Enforce correct state for correct clock handling.
82 # Because we don't know if this is bit communication or a
83 # status check we have to collect the SI and SO values on SK
84 # edges while the chip is selected and figure out afterwards.
88 packet.append({'samplenum': self.samplenum,
89 'matched': self.matched,
90 'cs': cs, 'sk': sk, 'si': si, 'so': so})
92 cs, sk, si, so = self.wait([{0: 'l'}, {1: 'r'}, {3: 'e'}])
94 cs, sk, si, so = self.wait([{0: 'l'}, {1: 'f'}, {3: 'e'}])
96 packet.append({'samplenum': self.samplenum,
97 'matched': self.matched,
98 'cs': cs, 'sk': sk, 'si': si, 'so': so})
100 # Figure out if this is a status check.
101 # Either there is no clock or no start bit (on first rising edge).
103 for change in packet:
104 # Get first clock rising edge.
105 if len(change['matched']) > 1 and change['matched'][1] \
111 # The packet is for a status check.
112 # SO low = busy, SO high = ready.
113 # The SO signal might be noisy in the beginning because it starts
116 start_samplenum = packet[0]['samplenum']
117 bit_so = packet[0]['so']
118 # Check for SO edges.
119 for change in packet:
120 if len(change['matched']) > 2 and change['matched'][2]:
121 if bit_so == 0 and change['so']:
122 # Rising edge Busy -> Ready.
123 self.put(start_samplenum, change['samplenum'],
124 self.out_ann, [3, ['Busy', 'B']])
125 start_samplenum = change['samplenum']
126 bit_so = change['so']
129 self.put(start_samplenum, packet[-1]['samplenum'],
130 self.out_ann, [3, ['Busy', 'B']])
132 self.put(start_samplenum, packet[-1]['samplenum'],
133 self.out_ann, [3, ['Ready', 'R']])
136 # Since the slave samples SI on clock rising edge we do the
137 # same. Because the slave changes SO on clock rising edge we
138 # sample on the falling edge.
139 bit_start = 0 # Rising clock sample of bit start.
140 bit_si = 0 # SI value at rising clock edge.
141 bit_so = 0 # SO value at falling clock edge.
142 start_bit = True # Start bit incoming (first bit).
143 python_output = [] # Python output data.
144 for change in packet:
145 if len(change['matched']) > 1 and change['matched'][1]:
147 if change['sk']: # Rising clock edge.
148 if bit_start > 0: # Bit completed.
150 if bit_si == 0: # Start bit missing.
151 self.put(bit_start, change['samplenum'],
153 [4, ['Start bit not high',
156 self.put(bit_start, change['samplenum'],
158 [0, ['Start bit', 'S']])
161 self.put(bit_start, change['samplenum'],
163 [1, ['SI bit: %d' % bit_si,
166 self.put(bit_start, change['samplenum'],
168 [2, ['SO bit: %d' % bit_so,
171 python_output.append({'ss': bit_start,
172 'se': change['samplenum'],
173 'si': bit_si, 'so': bit_so})
174 bit_start = change['samplenum']
175 bit_si = change['si']
176 else: # Falling clock edge.
177 bit_so = change['so']
178 elif change['matched'][0] and \
179 change['cs'] == 0 and change['sk'] == 0:
181 self.put(bit_start, change['samplenum'], self.out_ann,
182 [1, ['SI bit: %d' % bit_si,
183 'SI: %d' % bit_si, '%d' % bit_si]])
184 self.put(bit_start, change['samplenum'], self.out_ann,
185 [2, ['SO bit: %d' % bit_so,
186 'SO: %d' % bit_so, '%d' % bit_so]])
187 python_output.append({'ss': bit_start,
188 'se': change['samplenum'],
189 'si': bit_si, 'so': bit_so})
190 self.put(packet[0]['samplenum'],
191 packet[len(packet) - 1]['samplenum'],
192 self.out_python, python_output)