GPIO, or General Purpose Input Output, is the main way you'll interface with simple or obscure bits of hardware. This tutorial will introduce the GPIO system and how to use it.
On the side of your brainbox, there are 4 regular pins and a "+5v" and "-" pin. The top of the brain box labels which pin corresponds to which number. Different devices need to be plugged into different pins.
GPIO outputs are already protected by a 1k Ohm current limiting resistor, you can connect LEDs directly!
If you want to put an LED on your robot, for testing or just for looks, you'll need to plug one side of the LED into the
- (gound) pin, and the other side of the LED into any regular pin (such as 1). Then, use the following code to set up the pin in
OUTPUT mode and turn the LED on:
import robot R = robot.Robot() # If you're not using GPIO pin 1, change this number to whatever pin you're using. R.gpio.mode = robot.OUTPUT R.gpio.digital = True
Try using a loop to make the light turn on and off every 2 seconds. You'll need the time library from the motors exercise.
While your robot hopefully won't be colliding with much, buttons are a good way for a robot to know if it's driven into something. Buttons should be plugged into the - pin and a regular pin (such as 1). Using the
INPUT_PULLUP mode, you can detect when a button is pressed.
import robot import time R = robot.Robot() # If you're not using GPIO pin 1, change this number to whatever pin you're using. R.gpio.mode = robot.INPUT while True: if R.gpio.digital: print("Pressed") else: print("Not Pressed") time.sleep(0.1)
Try making a light turn on or off depending on if a button is pressed. An explaination of why it is needed to use
INPUT_PULLUP can be found in the GPIO documentation.
Another form of input is a potentiometer or a variable resistor. Potentiometers should be plugged into the +5v, a regular pin (such as 3) and the - pin. Using
INPUT_ANALOG mode, you can read the voltage output of the resistor (between 0V and 5V).
import robot R = robot.Robot() POT_PIN = 3 R.gpio[POT_PIN].mode = robot.INPUT_ANALOG while True: print(R.gpio[POT_PIN].analog)