1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
|
# Copyright 2013 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Interface for a USB-connected Monsoon power meter.
http://msoon.com/LabEquipment/PowerMonitor/
Currently Unix-only. Relies on fcntl, /dev, and /tmp.
"""
import collections
import logging
import os
import select
import struct
import time
import serial # pylint: disable=import-error,no-name-in-module
import serial.tools.list_ports # pylint: disable=import-error,no-name-in-module
Power = collections.namedtuple('Power', ['amps', 'volts'])
class Monsoon(object):
"""Provides a simple class to use the power meter.
mon = monsoon.Monsoon()
mon.SetVoltage(3.7)
mon.StartDataCollection()
mydata = []
while len(mydata) < 1000:
mydata.extend(mon.CollectData())
mon.StopDataCollection()
"""
def __init__(self, device=None, serialno=None, wait=True):
"""Establish a connection to a Monsoon.
By default, opens the first available port, waiting if none are ready.
A particular port can be specified with 'device', or a particular Monsoon
can be specified with 'serialno' (using the number printed on its back).
With wait=False, IOError is thrown if a device is not immediately available.
"""
assert float(serial.VERSION) >= 2.7, \
'Monsoon requires pyserial v2.7 or later. You have %s' % serial.VERSION
self._coarse_ref = self._fine_ref = self._coarse_zero = self._fine_zero = 0
self._coarse_scale = self._fine_scale = 0
self._last_seq = 0
self._voltage_multiplier = None
if device:
self.ser = serial.Serial(device, timeout=1)
return
while 1:
for (port, desc, _) in serial.tools.list_ports.comports():
if not desc.lower().startswith('mobile device power monitor'):
continue
tmpname = '/tmp/monsoon.%s.%s' % (os.uname()[0], os.path.basename(port))
self._tempfile = open(tmpname, 'w')
try: # Use a lockfile to ensure exclusive access.
# Put the import in here to avoid doing it on unsupported platforms.
import fcntl # pylint: disable=import-error
fcntl.lockf(self._tempfile, fcntl.LOCK_EX | fcntl.LOCK_NB)
except IOError:
logging.error('device %s is in use', port)
continue
try: # Try to open the device.
self.ser = serial.Serial(port, timeout=1)
self.StopDataCollection() # Just in case.
self._FlushInput() # Discard stale input.
status = self.GetStatus()
except IOError, e:
logging.error('error opening device %s: %s', port, e)
continue
if not status:
logging.error('no response from device %s', port)
elif serialno and status['serialNumber'] != serialno:
logging.error('device %s is #%d', port, status['serialNumber'])
else:
if status['hardwareRevision'] == 1:
self._voltage_multiplier = 62.5 / 10**6
else:
self._voltage_multiplier = 125.0 / 10**6
return
self._tempfile = None
if not wait:
raise IOError('No device found')
logging.info('waiting for device...')
time.sleep(1)
def GetStatus(self):
"""Requests and waits for status. Returns status dictionary."""
# status packet format
STATUS_FORMAT = '>BBBhhhHhhhHBBBxBbHBHHHHBbbHHBBBbbbbbbbbbBH'
STATUS_FIELDS = [
'packetType', 'firmwareVersion', 'protocolVersion',
'mainFineCurrent', 'usbFineCurrent', 'auxFineCurrent', 'voltage1',
'mainCoarseCurrent', 'usbCoarseCurrent', 'auxCoarseCurrent', 'voltage2',
'outputVoltageSetting', 'temperature', 'status', 'leds',
'mainFineResistor', 'serialNumber', 'sampleRate',
'dacCalLow', 'dacCalHigh',
'powerUpCurrentLimit', 'runTimeCurrentLimit', 'powerUpTime',
'usbFineResistor', 'auxFineResistor',
'initialUsbVoltage', 'initialAuxVoltage',
'hardwareRevision', 'temperatureLimit', 'usbPassthroughMode',
'mainCoarseResistor', 'usbCoarseResistor', 'auxCoarseResistor',
'defMainFineResistor', 'defUsbFineResistor', 'defAuxFineResistor',
'defMainCoarseResistor', 'defUsbCoarseResistor', 'defAuxCoarseResistor',
'eventCode', 'eventData',
]
self._SendStruct('BBB', 0x01, 0x00, 0x00)
while 1: # Keep reading, discarding non-status packets.
data = self._ReadPacket()
if not data:
return None
if len(data) != struct.calcsize(STATUS_FORMAT) or data[0] != '\x10':
logging.debug('wanted status, dropped type=0x%02x, len=%d',
ord(data[0]), len(data))
continue
status = dict(zip(STATUS_FIELDS, struct.unpack(STATUS_FORMAT, data)))
assert status['packetType'] == 0x10
for k in status.keys():
if k.endswith('VoltageSetting'):
status[k] = 2.0 + status[k] * 0.01
elif k.endswith('FineCurrent'):
pass # Needs calibration data.
elif k.endswith('CoarseCurrent'):
pass # Needs calibration data.
elif k.startswith('voltage') or k.endswith('Voltage'):
status[k] = status[k] * 0.000125
elif k.endswith('Resistor'):
status[k] = 0.05 + status[k] * 0.0001
if k.startswith('aux') or k.startswith('defAux'):
status[k] += 0.05
elif k.endswith('CurrentLimit'):
status[k] = 8 * (1023 - status[k]) / 1023.0
return status
def SetVoltage(self, v):
"""Set the output voltage, 0 to disable."""
if v == 0:
self._SendStruct('BBB', 0x01, 0x01, 0x00)
else:
self._SendStruct('BBB', 0x01, 0x01, int((v - 2.0) * 100))
def SetStartupCurrent(self, a):
"""Set the max startup output current. the unit of |a| : Amperes """
assert a >= 0 and a <= 8
val = 1023 - int((a/8.0)*1023)
self._SendStruct('BBB', 0x01, 0x08, val & 0xff)
self._SendStruct('BBB', 0x01, 0x09, val >> 8)
def SetMaxCurrent(self, a):
"""Set the max output current. the unit of |a| : Amperes """
assert a >= 0 and a <= 8
val = 1023 - int((a/8.0)*1023)
self._SendStruct('BBB', 0x01, 0x0a, val & 0xff)
self._SendStruct('BBB', 0x01, 0x0b, val >> 8)
def SetUsbPassthrough(self, val):
"""Set the USB passthrough mode: 0 = off, 1 = on, 2 = auto."""
self._SendStruct('BBB', 0x01, 0x10, val)
def StartDataCollection(self):
"""Tell the device to start collecting and sending measurement data."""
self._SendStruct('BBB', 0x01, 0x1b, 0x01) # Mystery command.
self._SendStruct('BBBBBBB', 0x02, 0xff, 0xff, 0xff, 0xff, 0x03, 0xe8)
def StopDataCollection(self):
"""Tell the device to stop collecting measurement data."""
self._SendStruct('BB', 0x03, 0x00) # Stop.
def CollectData(self):
"""Return some current samples. Call StartDataCollection() first."""
while 1: # Loop until we get data or a timeout.
data = self._ReadPacket()
if not data:
return None
if len(data) < 4 + 8 + 1 or data[0] < '\x20' or data[0] > '\x2F':
logging.debug('wanted data, dropped type=0x%02x, len=%d',
ord(data[0]), len(data))
continue
seq, packet_type, x, _ = struct.unpack('BBBB', data[:4])
data = [struct.unpack(">hhhh", data[x:x+8])
for x in range(4, len(data) - 8, 8)]
if self._last_seq and seq & 0xF != (self._last_seq + 1) & 0xF:
logging.info('data sequence skipped, lost packet?')
self._last_seq = seq
if packet_type == 0:
if not self._coarse_scale or not self._fine_scale:
logging.info('waiting for calibration, dropped data packet')
continue
out = []
for main, usb, _, voltage in data:
main_voltage_v = self._voltage_multiplier * (voltage & ~3)
sample = 0.0
if main & 1:
sample += ((main & ~1) - self._coarse_zero) * self._coarse_scale
else:
sample += (main - self._fine_zero) * self._fine_scale
if usb & 1:
sample += ((usb & ~1) - self._coarse_zero) * self._coarse_scale
else:
sample += (usb - self._fine_zero) * self._fine_scale
out.append(Power(sample, main_voltage_v))
return out
elif packet_type == 1:
self._fine_zero = data[0][0]
self._coarse_zero = data[1][0]
elif packet_type == 2:
self._fine_ref = data[0][0]
self._coarse_ref = data[1][0]
else:
logging.debug('discarding data packet type=0x%02x', packet_type)
continue
if self._coarse_ref != self._coarse_zero:
self._coarse_scale = 2.88 / (self._coarse_ref - self._coarse_zero)
if self._fine_ref != self._fine_zero:
self._fine_scale = 0.0332 / (self._fine_ref - self._fine_zero)
def _SendStruct(self, fmt, *args):
"""Pack a struct (without length or checksum) and send it."""
data = struct.pack(fmt, *args)
data_len = len(data) + 1
checksum = (data_len + sum(struct.unpack('B' * len(data), data))) % 256
out = struct.pack('B', data_len) + data + struct.pack('B', checksum)
self.ser.write(out)
def _ReadPacket(self):
"""Read a single data record as a string (without length or checksum)."""
len_char = self.ser.read(1)
if not len_char:
logging.error('timeout reading from serial port')
return None
data_len = struct.unpack('B', len_char)
data_len = ord(len_char)
if not data_len:
return ''
result = self.ser.read(data_len)
if len(result) != data_len:
return None
body = result[:-1]
checksum = (data_len + sum(struct.unpack('B' * len(body), body))) % 256
if result[-1] != struct.pack('B', checksum):
logging.error('invalid checksum from serial port')
return None
return result[:-1]
def _FlushInput(self):
"""Flush all read data until no more available."""
self.ser.flush()
flushed = 0
while True:
ready_r, _, ready_x = select.select([self.ser], [], [self.ser], 0)
if len(ready_x) > 0:
logging.error('exception from serial port')
return None
elif len(ready_r) > 0:
flushed += 1
self.ser.read(1) # This may cause underlying buffering.
self.ser.flush() # Flush the underlying buffer too.
else:
break
if flushed > 0:
logging.debug('dropped >%d bytes', flushed)
|
