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Raspberry pi 3 GPIO not working

byrd

I am currently trying to turn an LED off but it is not working. (LED is always on, yes I do have a resistor 220 ohm)

 

I have Wiringpi installed and looking at the readall data I do not see any change when I run my commands.

 

I have tried directly in the python program, creating a python script and running it, running python from terminal, and using the wiringpi gpio commands. I have also tried doing all of this with sudo as well.

 

import RPi.GPIO as gpio
gpio.setmode(gpio.BCM)
gpio.setup(17, gpio.OUT)
gpio.output(17, False)

Parents
  • 0

    I have spent years collecting vital information about the various releases of the Pi to document the differences so that I can apply that to GPIO operations. It's about time I got on with actual bit bashing.

     

    I got this from the official raspberry GPIO Python site,

     

    https://sourceforge.net/p/raspberry-gpio-python/wiki/Examples/

     

    To specify which you are using (mandatory):

    GPIO.setmode(GPIO.BOARD)
       # or 
    GPIO.setmode(GPIO.BCM)

    You are using the numbering of the GPIO pins on the BCM controller rather than the BOARD numbers of the Raspberry Pi GPIO. The following chart does not relate to all Pi revisions, but should be OK for the Pi 3.

    image

    So the BCM GPIO pin 17 (the one you are controlling) is actually Raspberry Pi GPIO pin 11. Could this be the problem? I notice that Pi pin 17 is a 3.3Volt pin which would light any LED via a resistor to Ground.

  • 0 in reply to royleith

    I have tried using GPIO.BOARD and changing pin 11's output to False and nothing happened.image

     

    I have tried flashing the LED as well and it didn't do anything.

     

    i have found out while targeting other pins and reading the readall data that I am able to change all the gpio pins modes, but some i cannot change the output. 17 for instance will not change from 1 to 0 but the rest do.

     

    I have moved over my jumper wire from 17 to all other pins but nothing happens. If they're off and I turn them on the LED doesn't come on, and vice versa if they're on by default and I turn them off the LED stays on

  • 0 in reply to byrd

    Wait!....

    As far as I know there are two numbering schemes. NEITHER uses the pin number on the connector.

     

    Can you try "sudo apt-get install wiringpi" and then "gpio readall". That should give you an overview of what is currently configured.

     

    As bcm pin 17 is listed as wiring pi pin number zero, I would then test:

    gpio mode 0 OUT and verify that something changed by using gpio readall again. I just did that for you on my pi and I see:

    | 17 | 0 | GPIO. 0 | IN | 0 | 11 || 12 | 0 | IN | GPIO. 1 | 1 | 18 |

    changed into:

    | 17 | 0 | GPIO. 0 | OUT | 0 | 11 || 12 | 0 | IN | GPIO. 1 | 1 | 18 |

    Now, on my pi the led would be off, as the output value is low, but

    gpio write 0 1

    would turn it on:

    | 17 | 0 | GPIO. 0 | OUT | 1 | 11 || 12 | 0 | IN | GPIO. 1 | 1 | 18 |

    This eliminates possible errors with you interacting with the python, and verifies the hardware.

     

    Worst case you've already blown up that GPIO output of the pi with some earlier experiment.....

     

    Another theory.... Could it be that you have the cable between the pi and the breadboard inverted? The side of the cable with the red pin goes FURTHEST away from the USB and ethernet connectors.

  • 0 in reply to rew

    The ribbon cable was inverted..... Wow that's completely my fault for not reading the instructions clear enough, I just went back and read them and it says which side should be where.

     

    Thank you all for pitching in to help me! This was my first post on this site and the responses were quick and helpful. I'll be sticking around here for a while!

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