This is a simple add-on board for the Raspberry Pi with three LEDs and a push-button switch. A sample bit of Python code is shown below to flash the LEDs in response to the switch being pressed. There’s also the option to add a low-cost DHT11 temperature/humidity sensor to build a simple datalogger.
Here’s a little bit of code you can use to test the board. Use a text editor to enter the code and save it in a file called led_flasher.py which you can then run by typing sudo python led_flasher.py
import RPi.GPIO as GPIO import time def led_on_and_pause(pin): GPIO.output(pin, GPIO.HIGH) # LED on if (GPIO.input(9) == GPIO.LOW): time.sleep(0.2) # switch pressed else: time.sleep(1) # switch NOT pressed GPIO.output(pin, GPIO.LOW) # LED off # Note: the switch requires use of the # Pi's internal pull-up resistors hence the # GPIO.PUD_UP in the setup code below. GPIO.setmode(GPIO.BCM) GPIO.setup(17, GPIO.OUT) # red GPIO.setup(22, GPIO.OUT) # yellow GPIO.setup(10, GPIO.OUT) # green GPIO.setup(9, GPIO.IN, GPIO.PUD_UP) # switch for i in range(100): led_on_and_pause(17) # red led_on_and_pause(22) # yellow led_on_and_pause(10) # green GPIO.cleanup()
If you’ve got one of the blue DHT11 temperature/humidity sensors attached to your board, you should look at Adafruit’s excellent tutorial – the DHT11 on your board is wired to GPIO pin BCM4 as suggested by Adafruit, so you can skip the wiring instructions!