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Failed to import ADCPi from python system path

604 Views - Created 19/11/2018


Posted by:

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When I try to run the code from ADCPi, demo_readvoltage.py, I get the following error:

Failed to import ADCPi from python system path
Importing from parent folder instead
Traceback (most recent call last):
  File "demo_readvoltage.py", line 61, in <module>
  File "demo_readvoltage.py", line 40, in main
    adc = ADCPi(0x68, 0x69, 12)
  File "../ADCPi.py", line 128, in __init__
    self.__bus = self.__get_smbus()
  File "../ADCPi.py", line 84, in __get_smbus
    raise IOError('Could not open the i2c bus')
IOError: Could not open the i2c bus

Does anyone know what could causing this error and how i can fix it?


Posted by:

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Here is the code from demo_readvoltage.py,


#!/usr/bin/env python
ABElectronics ADC Pi 8-Channel ADC demo

Requires python smbus to be installed
run with: python demo_readvoltage.py

Initialise the ADC device using the default addresses and sample rate,
change this value if you have changed the address selection jumpers

Sample rate can be 12,14, 16 or 18

from __future__ import absolute_import, division, print_function, \
import time
import os

    from ABElectronics_Python_Libraries import ADCPi
except ImportError:
    print("Failed to import ADCPi from python system path")
    print("Importing from parent folder instead")
        import sys
        from ADCPi import ADCPi
    except ImportError:
        raise ImportError(
            "Failed to import library from parent folder")

def main():
    Main program function

    adc = ADCPi(0x68, 0x69, 12)

    while True:

        # clear the console

        # read from adc channels and print to screen
        print("Channel 1: %02f" % adc.read_voltage(1))
        print("Channel 2: %02f" % adc.read_voltage(2))
        print("Channel 3: %02f" % adc.read_voltage(3))
        print("Channel 4: %02f" % adc.read_voltage(4))
        print("Channel 5: %02f" % adc.read_voltage(5))
        print("Channel 6: %02f" % adc.read_voltage(6))
        print("Channel 7: %02f" % adc.read_voltage(7))
        print("Channel 8: %02f" % adc.read_voltage(8))

        # wait 0.2 seconds before reading the pins again

if __name__ == "__main__":


Posted by:

Users Avatar

United Kingdom

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The error you are getting normally means the I2C bus is not configured correctly.  Can you try going through our I2C tutorial to set up the I2C bus on the Raspberry Pi.

Once you have gone through the tutorial try running the command "sudo i2cdetect -y 1".  It should list all of the I2C devices that are visible to the Raspberry Pi, the ADC Pi should be on 0x68 and 0x69.  If it is showing up then you should be able to use the ADC Pi with our software libraries.  If it is not showing up then check the solder joints on the 40 pin GPIO connector and the address header to make sure there are no dry joints or solder bridges.

AB Electronics UK Tech Support

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