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pitrafficlight_python_example [2015/08/13 21:33] (current)
eric created
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 +====== Pi Traffic Light Python Example ======
 +This is an example of how to use Python to control the LEDs of the Pi Traffic light http://​lowvoltagelabs.com/​products/​pi-traffic/​
 +
 +See the [[pitrafficlight|hardware installation]] page for information on installing the Pi Traffic light on the Raspberry Pi.
 +
 +{{:​pi_traffic_installed_yellow_led_on.jpg?​direct&​300|}}
 +
 +==== Software Setup ====
 +If the Python RPi.GPIO module is not already installed go to https://​pypi.python.org/​pypi/​RPi.GPIO to download the module.
 +
 +==== LED control ====
 +The three LEDs are setup in such a way that a high voltage turns the LEDs ON. In terms that the Python module understands that means to turn on an LED you set the output pin to True.
 +
 +The LEDs are connected to the following pins:
 +  * pin 9 = Red LED
 +  * pin 10 = Yellow LED
 +  * pin 11 = Green LED
 +
 +In Python the pins first need to be setup as outputs then set to True to turn the LED on or False to turn the LED off.
 +
 +  # Pin Setup:
 +  GPIO.setmode(GPIO.BCM) ​  # Broadcom pin-numbering scheme. This uses the pin numbers that match the pin numbers on the Pi Traffic light.
 +  GPIO.setup(9,​ GPIO.OUT) ​  # Red LED pin set as output
 +  # Set the pin HIGH
 +  GPIO.output(9,​ True)  # Turns on the Red LED
 +  # Set the pin LOW
 +  GPIO.output(9,​ False) ​ # Turns off the Red LED
 +
 +To use the Yellow and Green LEDs first set those pins to output:
 +
 +  GPIO.setup(10,​ GPIO.OUT) ​  # Yellow LED pin set as output
 +  GPIO.setup(11,​ GPIO.OUT) ​  # Green LED pin set as output
 +
 +Then use the GPIO.output statement to set the pins to True or False.
  
pitrafficlight_python_example.txt ยท Last modified: 2015/08/13 21:33 by eric