STM32F4xx FreeRTOS transmitter demo

Demonstration of different FreeRTOS capabilities via a simple code example

Business requirements

• Read the state of a button (CN8 A5 pin, GPIO port C, pin 0)
• Switch on the LED if button is pressed
• Switch off the LED if button is released
• Send the button state info to host pc via UART
• Measure a voltage source connected to analog input (CN8 A0 pin) every 200 ms
• Send the measurements to host via UART

Solution Design - Tasks

• Button state read
• ADC voltage read
• LED switcher
• Transmit UART message
• Button test signal (helper task)

Solution Design – Inter-task Communication

• Button -> LED: Semaphore
• Button -> UART: Semaphore
• ADC -> UART: Queue

Solution Design – Task Priorities

• Button state read - high
• Transmit UART message - above normal
• ADC voltage read - normal
• LED switcher - below normal
• Button test signal - below normal

Technical details

• Board: STM32 Nucleo-F446RE
• Toolchain: STM32CubeIDE Version: 1.5.1 (C) 2020 STMicroelectronics ALL RIGHTS RESERVED
• Middleware: FreeRTOS v10.2.1 CMSIS v2 Copyright (C) Amazon Web Services, Inc. or its affiliates. All rights reserved.