Detect a button press

We are now going to make the LED ligth only when we press a button, we will create a project that reads the state of the button GPIO and reacts to its state.

Setup

✅ Go to intro/button directory.

✅ Open the prepared project skeleton in intro/button.

✅ Open the docs for this project with the following command:

cargo doc --open

intro/button/examples/button.rs contains the solution. You can run it with the following command:

cargo run --release --example button

Exercise

Most of the dev-boards have a button, in our case, we will use the one labeled BOOT on GPIO9.

✅ Initiate the Io peripheral, and create variable for the LED and button, the LED can be created using the into_push_pull_output function as before while the button can be obtained using into_pull_up_input function.

Similarly to turning a GPIO into an output we can turn it into an input. Then we can get the current state of the input pin with is_high and similar functions.

✅ In the loop, add some logic so if the button is not pressed, the LED is lit. If the button is pressed, the LED is off.

Simulation

This project is available for simulation through two methods:

• Wokwi projects:
  • Exercise: Currently not available
  • Solution
• Wokwi files are also present in the project folder to simulate it with Wokwi VS Code extension:
  1. Press F1, select Wokwi: Select Config File and choose intro/button/wokwi.toml
     • Edit the wokwi.toml file to select between exercise and solution simulation
  2. Build you project
  3. Press F1 again and select Wokwi: Start Simulator