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Milton Eduardo Sosa 87a8b74908 Add example to poll encoder and display value on I2C display (#963 ) Co-authored-by: Milton Eduardo Sosa <milton@Miltons-MacBook-Pro.local>		2024-10-02 18:46:42 +00:00
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README.md	Add example to poll encoder and display value on I2C display (#963 )	2024-10-02 18:46:42 +00:00

README.md

STM32F411CEU6 encoder polling and LCD display

This example uses an STM32F411CEU6 microcontroller on the Blackpill board to interface with an I2C LCD display and a rotary encoder.

Features

Rotary Encoder Integration: Reads input from a rotary encoder to adjust a value.
I2C LCD Display: Displays the current encoder value on an I2C-connected HD44780 LCD.

Working principle

The hardware task tim2_timeout_interrupt_handler polls the encoder state on each interrupt generated by TIM2, and updates the displayed value accordingly.

Code Overview

Key Components

Knob Struct: Placeholder for the rotary encoder and its current value.
LCD I2C Communication: Uses I2C protocol to communicate with the HD44780 LCD.
Timers: Utilizes TIM1 for delays and TIM2 for polling the rotary encoder.

Important Constants

LCD_I2C_ADDRESS: The I2C address of the LCD display.

Initialization

System Clock: Configured to use an external 25 MHz clock.
GPIO Setup: Configures GPIO pins for the LED, rotary encoder, and I2C communication.
I2C Initialization: Sets up the I2C bus for LCD communication.
LCD Initialization: Initializes the LCD and displays initial messages.
Timer Setup: Configures TIM2 at 2 kHz and generate interrupts.

Tasks and Handlers

idle: Background task that runs when no other tasks are active.
tim2_timeout_interrupt_handler: Handles interrupts generated by TIM2, updates the rotary encoder value, and displays the value on the LCD.

Utility Functions

u8_to_str(n: u8) -> [u8; 3]: Converts an 8-bit integer to a 3-character string representation.

Dependencies

hd44780-driver: Driver for HD44780 LCD over I2C.
rotary_encoder_embedded: Library for handling rotary encoders.
defmt: Logging framework for embedded systems.

How-to

Build

Run cargo build --release to compile the code. If you run it for the first time, it will take some time to download and compile dependencies.

Run

Install probe-rs and configure it using the debugging extension for VScode.
The output should look like this: