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K. Townsend
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‎Adafruit_ADS1x15/Adafruit_ADS1x15.py

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#!/usr/bin/python
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import time
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from Adafruit_I2C import Adafruit_I2C
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# ===========================================================================
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# ADS1x15 Class
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# ===========================================================================
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class ADS1x15:
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i2c = None
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# IC Identifiers
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__IC_ADS1015 = 0x00
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__IC_ADS1115 = 0x01
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# Pointer Register
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__ADS1015_REG_POINTER_MASK = 0x03
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__ADS1015_REG_POINTER_CONVERT = 0x00
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__ADS1015_REG_POINTER_CONFIG = 0x01
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__ADS1015_REG_POINTER_LOWTHRESH = 0x02
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__ADS1015_REG_POINTER_HITHRESH = 0x03
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# Config Register
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__ADS1015_REG_CONFIG_OS_MASK = 0x8000
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__ADS1015_REG_CONFIG_OS_SINGLE = 0x8000 # Write: Set to start a single-conversion
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__ADS1015_REG_CONFIG_OS_BUSY = 0x0000 # Read: Bit = 0 when conversion is in progress
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__ADS1015_REG_CONFIG_OS_NOTBUSY = 0x8000 # Read: Bit = 1 when device is not performing a conversion
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__ADS1015_REG_CONFIG_MUX_MASK = 0x7000
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__ADS1015_REG_CONFIG_MUX_DIFF_0_1 = 0x0000 # Differential P = AIN0, N = AIN1 (default)
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__ADS1015_REG_CONFIG_MUX_DIFF_0_3 = 0x1000 # Differential P = AIN0, N = AIN3
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__ADS1015_REG_CONFIG_MUX_DIFF_1_3 = 0x2000 # Differential P = AIN1, N = AIN3
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__ADS1015_REG_CONFIG_MUX_DIFF_2_3 = 0x3000 # Differential P = AIN2, N = AIN3
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__ADS1015_REG_CONFIG_MUX_SINGLE_0 = 0x4000 # Single-ended AIN0
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__ADS1015_REG_CONFIG_MUX_SINGLE_1 = 0x5000 # Single-ended AIN1
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__ADS1015_REG_CONFIG_MUX_SINGLE_2 = 0x6000 # Single-ended AIN2
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__ADS1015_REG_CONFIG_MUX_SINGLE_3 = 0x7000 # Single-ended AIN3
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__ADS1015_REG_CONFIG_PGA_MASK = 0x0E00
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__ADS1015_REG_CONFIG_PGA_6_144V = 0x0000 # +/-6.144V range
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__ADS1015_REG_CONFIG_PGA_4_096V = 0x0200 # +/-4.096V range
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__ADS1015_REG_CONFIG_PGA_2_048V = 0x0400 # +/-2.048V range (default)
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__ADS1015_REG_CONFIG_PGA_1_024V = 0x0600 # +/-1.024V range
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__ADS1015_REG_CONFIG_PGA_0_512V = 0x0800 # +/-0.512V range
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__ADS1015_REG_CONFIG_PGA_0_256V = 0x0A00 # +/-0.256V range
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__ADS1015_REG_CONFIG_MODE_MASK = 0x0100
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__ADS1015_REG_CONFIG_MODE_CONTIN = 0x0000 # Continuous conversion mode
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__ADS1015_REG_CONFIG_MODE_SINGLE = 0x0100 # Power-down single-shot mode (default)
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__ADS1015_REG_CONFIG_DR_MASK = 0x00E0
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__ADS1015_REG_CONFIG_DR_128SPS = 0x0000 # 128 samples per second
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__ADS1015_REG_CONFIG_DR_250SPS = 0x0020 # 250 samples per second
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__ADS1015_REG_CONFIG_DR_490SPS = 0x0040 # 490 samples per second
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__ADS1015_REG_CONFIG_DR_920SPS = 0x0050 # 920 samples per second
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__ADS1015_REG_CONFIG_DR_1600SPS = 0x0080 # 1600 samples per second (default)
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__ADS1015_REG_CONFIG_DR_2400SPS = 0x00A0 # 2400 samples per second
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__ADS1015_REG_CONFIG_DR_3300SPS = 0x00C0 # 3300 samples per second
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__ADS1015_REG_CONFIG_CMODE_MASK = 0x0010
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__ADS1015_REG_CONFIG_CMODE_TRAD = 0x0000 # Traditional comparator with hysteresis (default)
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__ADS1015_REG_CONFIG_CMODE_WINDOW = 0x0010 # Window comparator
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__ADS1015_REG_CONFIG_CPOL_MASK = 0x0008
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__ADS1015_REG_CONFIG_CPOL_ACTVLOW = 0x0000 # ALERT/RDY pin is low when active (default)
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__ADS1015_REG_CONFIG_CPOL_ACTVHI = 0x0008 # ALERT/RDY pin is high when active
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__ADS1015_REG_CONFIG_CLAT_MASK = 0x0004 # Determines if ALERT/RDY pin latches once asserted
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__ADS1015_REG_CONFIG_CLAT_NONLAT = 0x0000 # Non-latching comparator (default)
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__ADS1015_REG_CONFIG_CLAT_LATCH = 0x0004 # Latching comparator
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__ADS1015_REG_CONFIG_CQUE_MASK = 0x0003
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__ADS1015_REG_CONFIG_CQUE_1CONV = 0x0000 # Assert ALERT/RDY after one conversions
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__ADS1015_REG_CONFIG_CQUE_2CONV = 0x0001 # Assert ALERT/RDY after two conversions
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__ADS1015_REG_CONFIG_CQUE_4CONV = 0x0002 # Assert ALERT/RDY after four conversions
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__ADS1015_REG_CONFIG_CQUE_NONE = 0x0003 # Disable the comparator and put ALERT/RDY in high state (default)
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# Constructor
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def __init__(self, address=0x48, ic=__IC_ADS1015, debug=False):
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self.i2c = Adafruit_I2C(address)
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self.address = address
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self.debug = debug
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# Make sure the IC specified is valid
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if ((ic < self.__IC_ADS1015) | (ic > self.__IC_ADS1115)):
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if (self.debug):
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print "ADS1x15: Invalid IC. Using the ADS1015 by default"
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self.ic = __IC_ADS1015
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else:
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self.ic = ic
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def readADCSingleEnded(self, channel=0):
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"Gets a single-ended ADC reading from the specified channel (1 bit = 3mV)"
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# Default to channel 0 with invalid channel, or return -1?
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if (channel > 3):
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if (self.debug):
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print "ADS1x15: Invalid channel specified: %d" % channel
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return -1
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# Start with default values
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config = self.__ADS1015_REG_CONFIG_CQUE_NONE | \
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self.__ADS1015_REG_CONFIG_CLAT_NONLAT | \
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self.__ADS1015_REG_CONFIG_CPOL_ACTVLOW | \
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self.__ADS1015_REG_CONFIG_CMODE_TRAD | \
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self.__ADS1015_REG_CONFIG_DR_1600SPS | \
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self.__ADS1015_REG_CONFIG_MODE_SINGLE
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# Set PGA/voltage range (1 bit = 3mV using the default range)
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config |= self.__ADS1015_REG_CONFIG_PGA_6_144V # +/- 6.144V range
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if channel == 3:
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config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_3
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elif channel == 2:
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config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_2
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elif channel == 1:
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config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_1
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else:
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config |= self.__ADS1015_REG_CONFIG_MUX_SINGLE_0
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# Set 'start single-conversion' bit
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config |= self.__ADS1015_REG_CONFIG_OS_SINGLE
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# Write config register to the ADC
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bytes = [(config >> 8) & 0xFF, config & 0xFF]
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self.i2c.writeList(self.__ADS1015_REG_POINTER_CONFIG, bytes)
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# Wait for the ADC conversion to complete
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time.sleep(0.001)
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# Read the conversion results
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result = self.i2c.readList(self.__ADS1015_REG_POINTER_CONVERT, 2)
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if (self.ic == self.__IC_ADS1015):
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# Shift right 4 bits for the 12-bit ADS1015
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return ( ((result[0] << 8) | (result[1] & 0xFF)) >> 4 )
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else:
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# Return 16-bit value for the ADS1115
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return ( (result[0] << 8) | (result[1] & 0xFF) )
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def readADCDifferential01(self):
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"Gets a differential ADC reading from channels 0 and 1"
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def readADCDifferential23(self):
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"Gets a differential ADC reading from channels 2 and 3"
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def startSingleEndedComparator(self, channel, threshold):
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"Starts the comparator in single-ended mode on the specified channel"
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def getLastConversionResults(self):
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"Returns the last ADC conversion result"
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‎Adafruit_ADS1x15/Adafruit_I2C.py

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../Adafruit_I2C/Adafruit_I2C.py

‎Adafruit_ADS1x15/ads1015_example.py

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#!/usr/bin/python
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from Adafruit_ADS1x15 import ADS1x15
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# ============================================================================
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# Example Code
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# ============================================================================
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# Initialise the ADC using the default mode (IC = ADS1015, default address)
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adc = ADS1x15()
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# Read channel 0 and 1 in single-ended mode (1 bit = 3mV)
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result = adc.readADCSingleEnded(0)
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print "Channel 0 = %.3f V" % ((result * 3.0) / 1000.0)
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result = adc.readADCSingleEnded(1)
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print "Channel 1 = %.3f V" % ((result * 3.0) / 1000.0)
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