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Vaishnav-sabari-girish
Vaishnav-sabari-girish

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Embedded Rust on the ESP32 : Interfacing Button with ESP32

#rust #embeddedsystems #esp32 #hal

In my previous blog, we blinked an LED.

Now, we shall interface a button (inbuilt Flash Button), which is connected to GPOI0 to read button presses.

Getting Started

Let us create our new project

esp-generate --chip=esp32 button_press
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Open src/bin/main.rs file and type the below code

#![no_std] #![no_main] #![deny( clippy::mem_forget, reason = "mem::forget is generally not safe to do with esp_hal types, especially those \ holding buffers for the duration of a data transfer." )] use esp_backtrace as _; use esp_hal::{ delay::Delay, gpio::Level, gpio::{Input, InputConfig}, gpio::{Output, OutputConfig}, main }; use esp_println::println; esp_bootloader_esp_idf::esp_app_desc!(); #[main] fn main() -> ! { let peripherals = esp_hal::init(esp_hal::Config::default()); let mut led = Output::new(peripherals.GPIO2, Level::Low, OutputConfig::default()); let button = Input::new(peripherals.GPIO0, InputConfig::default()); let delay = Delay::new(); loop { if button.is_low() { led.set_high(); println!("Button Pressed"); delay.delay_millis(50); } else { led.set_low(); } } }
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Into the Code : Line-by-line explanation 

#![no_std]
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  • Removes the standard library to suit bare-metal embedded systems. 
#![no_main]
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  • Disables Rust's default entry point, enabling use of a custom embedded main function. 
#![deny( clippy::mem_forget, reason = "mem::forget is generally not safe to do with esp_hal types, especially those \ holding buffers for the duration of a data transfer." )]
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  • Prevents using mem::forget, which can cause resource leaks with peripherals like GPIOs. 
use esp_backtrace as _;
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  • Provides support for backtraces during panics, aiding debugging. 
use esp_hal::{ delay::Delay, gpio::Level, gpio::{Input, InputConfig}, gpio::{Output, OutputConfig}, main, };
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  • Brings in delay functionality, GPIO level enums, input/output pin types, and the custom entry macro. 
use esp_println::println;
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  • Enables logging via println!, useful for debugging over serial. 
esp_bootloader_esp_idf::esp_app_desc!();
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  • Embeds metadata (app version, timestamp, etc.) into the firmware.
#[main] fn main() -> ! {
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  • Entry point of the application. Uses -> ! since it loops forever. 
 let peripherals = esp_hal::init(esp_hal::Config::default());
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  • Initializes peripherals using default configuration. 
 let mut led = Output::new(peripherals.GPIO2, Level::Low, OutputConfig::default());
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  • Configures GPIO2 as an output pin, initially set to Low (LED off). 
 let button = Input::new(peripherals.GPIO0, InputConfig::default());
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  • Configures GPIO0 as an input pin (for reading a button's state). 
 let delay = Delay::new();
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  • Initializes a delay instance for blocking waits. 
 loop {
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  • Begins an infinite loop to continuously check the button and control the LED. 
 if button.is_low() {
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  • Checks if the button is pressed (logic Low, assuming pull-up setup). 
 led.set_high();
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  • Turns the LED on. 
 println!("Button Pressed");
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  • Logs button press to serial console. 
 delay.delay_millis(50);
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  • Adds a small delay for button debounce. 
 } else { led.set_low(); }
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  • If the button is not pressed, turns the LED off. 
 } }
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Outputs

Terminal Output

terminal op

Hardware Output

Important Links

  1. Getting Started Blog
  2. Blinking an LED Blog
  3. GitHub Repository

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