This repository was archived by the owner on Sep 30, 2019. It is now read-only.
-
Notifications
You must be signed in to change notification settings - Fork 681
/
Copy pathAdafruit_ADS1x15.py
181 lines (152 loc) · 7.77 KB
/
Adafruit_ADS1x15.py
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
#!/usr/bin/python
import time
import smbus
from Adafruit_I2C import Adafruit_I2C
# ===========================================================================
# ADS1x15 Class
# ===========================================================================
class ADS1x15:
i2c = None
# IC Identifiers
__IC_ADS1015 = 0x00
__IC_ADS1115 = 0x01
# Pointer Register
__ADS1015_REG_POINTER_MASK = 0x03
__ADS1015_REG_POINTER_CONVERT = 0x00
__ADS1015_REG_POINTER_CONFIG = 0x01
__ADS1015_REG_POINTER_LOWTHRESH = 0x02
__ADS1015_REG_POINTER_HITHRESH = 0x03
# Config Register
__ADS1015_REG_CONFIG_OS_MASK = 0x8000
__ADS1015_REG_CONFIG_OS_SINGLE = 0x8000 # Write: Set to start a single-conversion
__ADS1015_REG_CONFIG_OS_BUSY = 0x0000 # Read: Bit = 0 when conversion is in progress
__ADS1015_REG_CONFIG_OS_NOTBUSY = 0x8000 # Read: Bit = 1 when device is not performing a conversion
__ADS1015_REG_CONFIG_MUX_MASK = 0x7000
__ADS1015_REG_CONFIG_MUX_DIFF_0_1 = 0x0000 # Differential P = AIN0, N = AIN1 (default)
__ADS1015_REG_CONFIG_MUX_DIFF_0_3 = 0x1000 # Differential P = AIN0, N = AIN3
__ADS1015_REG_CONFIG_MUX_DIFF_1_3 = 0x2000 # Differential P = AIN1, N = AIN3
__ADS1015_REG_CONFIG_MUX_DIFF_2_3 = 0x3000 # Differential P = AIN2, N = AIN3
__ADS1015_REG_CONFIG_MUX_SINGLE_0 = 0x4000 # Single-ended AIN0
__ADS1015_REG_CONFIG_MUX_SINGLE_1 = 0x5000 # Single-ended AIN1
__ADS1015_REG_CONFIG_MUX_SINGLE_2 = 0x6000 # Single-ended AIN2
__ADS1015_REG_CONFIG_MUX_SINGLE_3 = 0x7000 # Single-ended AIN3
__ADS1015_REG_CONFIG_PGA_MASK = 0x0E00
__ADS1015_REG_CONFIG_PGA_6_144V = 0x0000 # +/-6.144V range
__ADS1015_REG_CONFIG_PGA_4_096V = 0x0200 # +/-4.096V range
__ADS1015_REG_CONFIG_PGA_2_048V = 0x0400 # +/-2.048V range (default)
__ADS1015_REG_CONFIG_PGA_1_024V = 0x0600 # +/-1.024V range
__ADS1015_REG_CONFIG_PGA_0_512V = 0x0800 # +/-0.512V range
__ADS1015_REG_CONFIG_PGA_0_256V = 0x0A00 # +/-0.256V range
__ADS1015_REG_CONFIG_MODE_MASK = 0x0100
__ADS1015_REG_CONFIG_MODE_CONTIN = 0x0000 # Continuous conversion mode
__ADS1015_REG_CONFIG_MODE_SINGLE = 0x0100 # Power-down single-shot mode (default)
__ADS1015_REG_CONFIG_DR_MASK = 0x00E0
__ADS1015_REG_CONFIG_DR_128SPS = 0x0000 # 128 samples per second
__ADS1015_REG_CONFIG_DR_250SPS = 0x0020 # 250 samples per second
__ADS1015_REG_CONFIG_DR_490SPS = 0x0040 # 490 samples per second
__ADS1015_REG_CONFIG_DR_920SPS = 0x0050 # 920 samples per second
__ADS1015_REG_CONFIG_DR_1600SPS = 0x0080 # 1600 samples per second (default)
__ADS1015_REG_CONFIG_DR_2400SPS = 0x00A0 # 2400 samples per second
__ADS1015_REG_CONFIG_DR_3300SPS = 0x00C0 # 3300 samples per second
__ADS1115_REG_CONFIG_DR_8SPS = 0x0000 # 8 samples per second
__ADS1115_REG_CONFIG_DR_16SPS = 0x0020 # 16 samples per second
__ADS1115_REG_CONFIG_DR_32SPS = 0x0040 # 32 samples per second
__ADS1115_REG_CONFIG_DR_64SPS = 0x0060 # 64 samples per second
__ADS1115_REG_CONFIG_DR_128SPS = 0x0080 # 128 samples per second
__ADS1115_REG_CONFIG_DR_250SPS = 0x00A0 # 250 samples per second (default)
__ADS1115_REG_CONFIG_DR_475SPS = 0x00C0 # 475 samples per second
__ADS1115_REG_CONFIG_DR_860SPS = 0x00E0 # 860 samples per second
__ADS1015_REG_CONFIG_CMODE_MASK = 0x0010
__ADS1015_REG_CONFIG_CMODE_TRAD = 0x0000 # Traditional comparator with hysteresis (default)
__ADS1015_REG_CONFIG_CMODE_WINDOW = 0x0010 # Window comparator
__ADS1015_REG_CONFIG_CPOL_MASK = 0x0008
__ADS1015_REG_CONFIG_CPOL_ACTVLOW = 0x0000 # ALERT/RDY pin is low when active (default)
__ADS1015_REG_CONFIG_CPOL_ACTVHI = 0x0008 # ALERT/RDY pin is high when active
__ADS1015_REG_CONFIG_CLAT_MASK = 0x0004 # Determines if ALERT/RDY pin latches once asserted
__ADS1015_REG_CONFIG_CLAT_NONLAT = 0x0000 # Non-latching comparator (default)
__ADS1015_REG_CONFIG_CLAT_LATCH = 0x0004 # Latching comparator
__ADS1015_REG_CONFIG_CQUE_MASK = 0x0003
__ADS1015_REG_CONFIG_CQUE_1CONV = 0x0000 # Assert ALERT/RDY after one conversions
__ADS1015_REG_CONFIG_CQUE_2CONV = 0x0001 # Assert ALERT/RDY after two conversions
__ADS1015_REG_CONFIG_CQUE_4CONV = 0x0002 # Assert ALERT/RDY after four conversions
__ADS1015_REG_CONFIG_CQUE_NONE = 0x0003 # Disable the comparator and put ALERT/RDY in high state (default)
# Constructor
def __init__(self, address=0x48, ic=__IC_ADS1015, debug=False):
# Depending on if you have an old or a new Raspberry Pi, you
# may need to change the I2C bus. Older Pis use SMBus 0,
# whereas new Pis use SMBus 1. If you see an error like:
# 'Error accessing 0x48: Check your I2C address '
# change the SMBus number in the initializer below!
self.i2c = Adafruit_I2C(address)
self.address = address
self.debug = debug
# Make sure the IC specified is valid
if ((ic < self.__IC_ADS1015) | (ic > self.__IC_ADS1115)):
if (self.debug):
print "ADS1x15: Invalid IC. Using the ADS1015 by default"
self.ic = __IC_ADS1015
else:
self.ic = ic
def readADCSingleEnded(self, channel=0):
"Gets a single-ended ADC reading from the specified channel (1 bit = 3mV)"
# Default to channel 0 with invalid channel, or return -1?
if (channel > 3):
if (self.debug):
print "ADS1x15: Invalid channel specified: %d" % channel
return -1
# Set default values
if (self.ic == self.__IC_ADS1015):
config = self.__ADS1015_REG_CONFIG_CQUE_NONE | \
self.__ADS1015_REG_CONFIG_CLAT_NONLAT | \
self.__ADS1015_REG_CONFIG_CPOL_ACTVLOW | \
self.__ADS1015_REG_CONFIG_CMODE_TRAD | \
self.__ADS1015_REG_CONFIG_DR_1600SPS | \
self.__ADS1015_REG_CONFIG_MODE_SINGLE
else:
config = self.__ADS1015_REG_CONFIG_CQUE_NONE | \
self.__ADS1015_REG_CONFIG_CLAT_NONLAT | \
self.__ADS1015_REG_CONFIG_CPOL_ACTVLOW | \
self.__ADS1015_REG_CONFIG_CMODE_TRAD | \
self.__ADS1115_REG_CONFIG_DR_250SPS | \
self.__ADS1015_REG_CONFIG_MODE_SINGLE
# Set PGA/voltage range to max value (+/- 6.144V)
config |= self.__ADS1015_REG_CONFIG_PGA_6_144V
if channel == 3:
config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_3
elif channel == 2:
config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_2
elif channel == 1:
config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_1
else:
config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_0
# Set 'start single-conversion' bit
config |= self.__ADS1015_REG_CONFIG_OS_SINGLE
# Write config register to the ADC
bytes = [(config >> 8) & 0xFF, config & 0xFF]
self.i2c.writeList(self.__ADS1015_REG_POINTER_CONFIG, bytes)
# Wait for the ADC conversion to complete
if (self.ic == self.__IC_ADS1015):
time.sleep(0.001)
else:
time.sleep(0.008)
# Read the conversion results
result = self.i2c.readList(self.__ADS1015_REG_POINTER_CONVERT, 2)
if (self.ic == self.__IC_ADS1015):
# Shift right 4 bits for the 12-bit ADS1015
return ( ((result[0] << 8) | (result[1] & 0xFF)) >> 4 )
else:
# Return 16-bit value for the ADS1115
# (Take signed values into account as well)
val = (result[0] << 8) | (result[1])
if val > 0x7FFF:
return val - 0xFFFF
else:
return (result[0] << 8) | (result[1])
def readADCDifferential01(self):
"Gets a differential ADC reading from channels 0 and 1"
def readADCDifferential23(self):
"Gets a differential ADC reading from channels 2 and 3"
def startSingleEndedComparator(self, channel, threshold):
"Starts the comparator in single-ended mode on the specified channel"
def getLastConversionResults(self):
"Returns the last ADC conversion result"