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--- gpio_led_control [2016/08/09 17:49] – walkeradmin
+++ gpio_led_control [2017/10/22 16:40] – walkeradmin
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-**Please be aware, the GPIO pins are 3.3v Logic, and are restricted to 16mA**
+**Please be aware, the GPIO pins are 3.3v Logic, and are restricted to 16mA - exceeding 16 mA will damage your Pi**
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+When the Pin goes high (under our software control) it will provide 3.3v, and thus the LED will light (famous last words)
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+If you are using your Raspberry Pi via SSH or a Remote Desktop session, you need to enable remote access of the GPIO Pins, instructions for this are [[enable_remote_access_to_gpio_pins|here]]:
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+Once you have connected the circuit, we can create the Python programme, in this example we will be doing it from the command line using the editor nano:
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+    sudo nano LED.py (starts the nano editor with a new file called LED.py)
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+Now enter this code: (you can copy and paste by the way)
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+    #import modules
+    import RPi.GPIO as GPIO    # This imports the GPIO libarary that allows the use of the GPIO pins,
+    import time                # This imports the time libarary (for delays among other things)
+                               # These libraries are built in to Raspbian.
+    GPIO.setmode (GPIO.BOARD)  # This sets the GPIO pin numbering. Our LED is connected to Pin 12,
+                               # so we can reference it by using BOARD as pin 12. However there is
+                               # another option (BCM) where we can reference a pin by it's name, pin
+                               # 12 is called GPIO18 (a reference to its place on the chip).
+    GPIO.setup(12, GPIO.OUT)   # Sets the GPIO pin as output. (as opposed to input, which would
+                               # read in a voltage (but only in terms of a 0 or a 1))
+    GPIO.output(12, 0)         # sets the GPIO Pin 12 to low (so 0v)
+    time.sleep(1)              # waits one second (settling time)
+    GPIO.output(12, 1)         # sets the GPIO Pin 12 to high (so 3.3v) LED will turn on
+    time.sleep(3)              # waits 3 seconds, so LED will be on for 3 seconds
+    GPIO.cleanup()             # Resets all the GPIO pins to their default state (LED will go off)
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+Because we are accessing the GPIO, we need to run our Python program as the sudo user:
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+    sudo python LED.py
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+The LED should come on for 3 seconds, then go off. The program will then end.
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+You can see it in operation Here: {{:led_video.mp4|950x574|autoplay,loop}}
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+**Remember:**
+Pins are 3.3v
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+mA MAX
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+This guide is comprised of information from a youtube video by **Gaven MacDonald**. Thanks Gaven.
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