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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. | ||