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1##
2## This file is part of the libsigrokdecode project.
3##
4## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
5##
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.
10##
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.
15##
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
19##
20
21# TODO: Better support for various LM75 compatible devices.
22
23import sigrokdecode as srd
24
25# LM75 only supports 9 bit resolution, compatible devices usually 9-12 bits.
26resolution = {
27 # CONFIG[6:5]: <resolution>
28 0x00: 9,
29 0x01: 10,
30 0x02: 11,
31 0x03: 12,
32}
33
34ft = {
35 # CONFIG[4:3]: <fault tolerance setting>
36 0x00: 1,
37 0x01: 2,
38 0x02: 4,
39 0x03: 6,
40}
41
42class Decoder(srd.Decoder):
43 api_version = 2
44 id = 'lm75'
45 name = 'LM75'
46 longname = 'National LM75'
47 desc = 'National LM75 (and compatibles) temperature sensor.'
48 license = 'gplv2+'
49 inputs = ['i2c']
50 outputs = ['lm75']
51 options = (
52 {'id': 'sensor', 'desc': 'Sensor type', 'default': 'lm75',
53 'values': ('lm75',)},
54 {'id': 'resolution', 'desc': 'Resolution (bits)', 'default': 9,
55 'values': (9, 10, 11, 12)},
56 )
57 annotations = (
58 ('celsius', 'Temperature in degrees Celsius'),
59 ('kelvin', 'Temperature in Kelvin'),
60 ('text-verbose', 'Human-readable text (verbose)'),
61 ('text', 'Human-readable text'),
62 ('warnings', 'Human-readable warnings'),
63 )
64
65 def __init__(self, **kwargs):
66 self.state = 'IDLE'
67 self.reg = 0x00 # Currently selected register
68 self.databytes = []
69
70 def start(self):
71 self.out_ann = self.register(srd.OUTPUT_ANN)
72
73 def putx(self, data):
74 # Helper for annotations which span exactly one I²C packet.
75 self.put(self.ss, self.es, self.out_ann, data)
76
77 def putb(self, data):
78 # Helper for annotations which span a block of I²C packets.
79 self.put(self.block_start, self.block_end, self.out_ann, data)
80
81 def warn_upon_invalid_slave(self, addr):
82 # LM75 and compatible devices have a 7-bit I²C slave address where
83 # the 4 MSBs are fixed to 1001, and the 3 LSBs are configurable.
84 # Thus, valid slave addresses (1001xxx) range from 0x48 to 0x4f.
85 if addr not in range(0x48, 0x4f + 1):
86 s = 'Warning: I²C slave 0x%02x not an LM75 compatible sensor.'
87 self.putx([4, [s % addr]])
88
89 def output_temperature(self, s, rw):
90 # TODO: Support for resolutions other than 9 bit.
91 before, after = self.databytes[0], (self.databytes[1] >> 7) * 5
92 celsius = float('%d.%d' % (before, after))
93 kelvin = celsius + 273.15
94 self.putb([0, ['%s: %.1f °C' % (s, celsius)]])
95 self.putb([1, ['%s: %.1f K' % (s, kelvin)]])
96
97 # Warn about the temperature register (0x00) being read-only.
98 if s == 'Temperature' and rw == 'WRITE':
99 s = 'Warning: The temperature register is read-only!'
100 self.putb([4, [s]])
101
102 def handle_temperature_reg(self, b, s, rw):
103 # Common helper for the temperature/T_HYST/T_OS registers.
104 if len(self.databytes) == 0:
105 self.block_start = self.ss
106 self.databytes.append(b)
107 return
108 self.databytes.append(b)
109 self.block_end = self.es
110 self.output_temperature(s, rw)
111 self.databytes = []
112
113 def handle_reg_0x00(self, b, rw):
114 # Temperature register (16bits, read-only).
115 self.handle_temperature_reg(b, 'Temperature', rw)
116
117 def handle_reg_0x01(self, b, rw):
118 # Configuration register (8 bits, read/write).
119 # TODO: Bit-exact annotation ranges.
120
121 sd = b & (1 << 0)
122 tmp = 'normal operation' if (sd == 0) else 'shutdown mode'
123 s = 'SD = %d: %s\n' % (sd, tmp)
124 s2 = 'SD = %s, ' % tmp
125
126 cmp_int = b & (1 << 1)
127 tmp = 'comparator' if (cmp_int == 0) else 'interrupt'
128 s += 'CMP/INT = %d: %s mode\n' % (cmp_int, tmp)
129 s2 += 'CMP/INT = %s, ' % tmp
130
131 pol = b & (1 << 2)
132 tmp = 'low' if (pol == 0) else 'high'
133 s += 'POL = %d: OS polarity is active-%s\n' % (pol, tmp)
134 s2 += 'POL = active-%s, ' % tmp
135
136 bits = (b & ((1 << 4) | (1 << 3))) >> 3
137 s += 'Fault tolerance setting: %d bit(s)\n' % ft[bits]
138 s2 += 'FT = %d' % ft[bits]
139
140 # Not supported by LM75, but by various compatible devices.
141 if self.options['sensor'] != 'lm75': # TODO
142 bits = (b & ((1 << 6) | (1 << 5))) >> 5
143 s += 'Resolution: %d bits\n' % resolution[bits]
144 s2 += ', resolution = %d' % resolution[bits]
145
146 self.putx([2, [s]])
147 self.putx([3, [s2]])
148
149 def handle_reg_0x02(self, b, rw):
150 # T_HYST register (16 bits, read/write).
151 self.handle_temperature_reg(b, 'T_HYST trip temperature', rw)
152
153 def handle_reg_0x03(self, b, rw):
154 # T_OS register (16 bits, read/write).
155 self.handle_temperature_reg(b, 'T_OS trip temperature', rw)
156
157 def decode(self, ss, es, data):
158 cmd, databyte = data
159
160 # Store the start/end samples of this I²C packet.
161 self.ss, self.es = ss, es
162
163 # State machine.
164 if self.state == 'IDLE':
165 # Wait for an I²C START condition.
166 if cmd != 'START':
167 return
168 self.state = 'GET SLAVE ADDR'
169 elif self.state == 'GET SLAVE ADDR':
170 # Wait for an address read/write operation.
171 if cmd in ('ADDRESS READ', 'ADDRESS WRITE'):
172 self.warn_upon_invalid_slave(databyte)
173 self.state = cmd[8:] + ' REGS' # READ REGS / WRITE REGS
174 elif self.state in ('READ REGS', 'WRITE REGS'):
175 if cmd in ('DATA READ', 'DATA WRITE'):
176 handle_reg = getattr(self, 'handle_reg_0x%02x' % self.reg)
177 handle_reg(databyte, cmd[5:]) # READ / WRITE
178 elif cmd == 'STOP':
179 # TODO: Any output?
180 self.state = 'IDLE'
181 else:
182 # self.putx([0, ['Ignoring: %s (data=%s)' % (cmd, databyte)]])
183 pass
184