Blinky

We will now create the iconic blinky.

Let's access the project with cd exercises/blinky.

On esp32-c6 board there is no regular LED connected, instead there is an addressable LED which works differently and is beyond the scope of this book.

Instead, we will use a regular LED and a resistor, and build a circuit controlled with the GPIO pin headers.

esp32-c6, wiring the LED

Wire up the board as shown on the previous image:

1. Start wiring from GND pin header (red wire).
2. From there to the resistor (220mΩ or larger, without it the LED blows up).
3. From the other leg of the resistor to the LED (blue wire).
4. Finally, the LED connects to pin-header 7 (the long LED-leg is on 7).

Let's reconsider our boilerplate:

#![no_std]
#![no_main]

use esp_backtrace as _;
use esp_println::println;
use esp_hal::{main, Config};

esp_bootloader_esp_idf::esp_app_desc!();

fn main() -> ! {
    let peripherals = esp_hal::init(Config::default());
}

And now we ask ourselves:

1. Which peripheral can we use to control pin-headers' electric state?
   • We can use the peripherals.GPIOX where X is the same number than the pin-header we need.
   • In this case, it's GPIO7, labelled 7. Always check the pinouts.

     Warning

     The PCB labels are written below the headers! So GPIO7 is not mapped onto header 6 (as a quick look might suggest), but on header 7.

2. Which driver can we use to communicate with it?
   • We can use the Input and / or Output drivers.

Exercise

0. Open the file src/main.rs, take some time to read the code.
1. Create OutputConfig with default configuration.
   • Hint: it implements Default.
2. Toggle the led with 3500ms delay.

The exercises/blinky/examples/blinky.rs contains a solution.

You can run it with the following command cargo run --example blinky --release.