Is my GPIO pin dead?

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1

Hi,

I am running:

BBB-eMMC-flasher-2013.06.20.img
and I installed Adafruit’s python library.

The Library seems to work fine. But after playing with a couple of A4988 stepper drivers, I think I may have killed a couple of GPIO pins, but I am not sure. I thought that there wouldn’t be any problem connecting a GPIO directly to the step, direction and enable pins of the stepper dirvers. I did have a 10k pull up resister (to 3.3) on the enable pin.

I never got the motor to step. Below is my very simple test script just to see it step. Measuring the voltage of the step pin, it is always 3.3 volts. Even if I set the time to 1 sec it never goes low. Testing the pin with a led and a 470ohm resistor, other pins work fine, but the pins I used for the stepper driver are always on.

So the question is, are they dead? Any help suggestion etc, would be greatly appreciated.

  1. import Adafruit_BBIO.GPIO as GPIO
  2. import time
  4. GPIO.setup(“P8_24”, GPIO.OUT) # Step
  5. GPIO.setup(“P8_5”, GPIO.OUT) # Dir
  6. GPIO.setup(“P8_27”, GPIO.OUT) # enable

GPIO.output(“P8_24”, GPIO.LOW)

GPIO.output(“P8_5”, GPIO.LOW)

GPIO.output(“P8_27”, GPIO.LOW)

  2. while True:
  3. GPIO.output(“P8_24”, GPIO.HIGH)
  4. time.sleep(0.01)
  5. GPIO.output(“P8_24”, GPIO.LOW)
  6. time.sleep(0.05)
2

Yep. I would expect that you have popped the processor. Only thing to do is to get the processor replaced via the RMA process.

http://circuitco.com/support/index.php?title=BeagleBoneBlack#RMA_Support

Gerald

3

Okay, so the good new is I didn’t kill the board.

I noticed this image (below). And the pins I was using are all in the MMC range. I was able to reboot the board from a MicroSD card. I think I scrambled the operating system when using the motor. Anyway, I changed the pins I was using to 8_8, 8_10 and 8_12 and I got the motor spinning. So lesson learned, not all GPIO pins are equal.

4

Well, all are not equal to what you are trying to do. They are not designed to drive motors direct.

And the ones marked for eMMC1, they connect to the eMMC on the board. If at all possible, you would be better of using other pins not so inclined.

Gerald

5

Yep. I trying to use the BBB as a micro controller.