1. Embedded-Systems-Projects

Projects and small projects of embedded systems using STM32F407xx or TM4C123.

Bare metal programming projects involving:

Master-slave communication using SPI, UART and I2C between STM32F407 / TM4C123xx and Arduino.
Development of drivers of SPI, UART, I2C, ADC e etc.
Traffic light control.
Bootloader
Measurement of distance using ultrasonic sensor
Servo-motors and PWM.
Development of drivers of STM32F407xx to communicate with LCD (HD44780)
Measurement of the frequency and period of signal coming from Arduino to TM4C123.

FreeRTOS projects:

Multitasking projects that use FreeRTOS, CMSIS and peripheral of STM32F407xx boards.

2. Description of main projects

2.1 ON-OFF temperature controller

It is a project based on the book "ARM-Based Microcontroller Multitasking Projects: Using the FreeRTOS Multitasking Kernel". It's an academic project that uses multitasking approach to control peripheral devices using real time operating systems (FreeRTOS).

Task	Resume of the Function
Task 1	It's the main function. It periodically reads the built-in temperature sensor and receives a setValue from Task 2. If the temperature is greater than the setValue, turn on the the LED. Otherwise, turn off. If the temperature is greater than a pre-defined value, turn on the buzzer.
Task 2	It's the UART controller. It sends a message to the PC, and reads the input (setValue) from the PC sending it to Task 1.
Task 3	LCD controller. It displays in the LCD the temperature and setValue received from Task 1.
Task 4	It turn on/off the buzzer. Task 1 sends that request.

Queue handle	Description	Used by Tasks
xUARTQueue	UART queue	Task 1, 2
xLCDQueue	LCD queue	Task 1, 3
xBuzzerQueue	Buzzer queue	Task 1, 4

Soft. Tools	Function
UART4	It's used to communicate STM32F407 with PC
ADC1	It's used to measure the built-in temperature
SPI2	It's used to communicate STM32F407 with LCD

This image shows this project, however, I didn't use a buzzer module since I didn't have it. So, instead, I used a LED. The image doesn't show clearly the LCD screen, it displays "Temperature: 51" and "Setpoint: 70".

Project's file: Book_Project \ Project_21

2.2 Distance measurement using TM4C123 and HC-SR04 ultrasonic sensor

Description: To find the distance from the ultrasonic sensor to an object, do the following. TM4C123 produces a 10 microsecond pulse to trigger the pin (PB4) of the sensor. Thus, the sensor produces 8 pulses of ultra-sound waves and each pulse has 40Khz of frequency. As soon as all eight pulses are transmitted through the air, the echo pin goes HIGH. In other words, the output echo pin makes transition from an active LOW to active HIGH (rising edge). The echo pin remains HIGH until the sound wave reaches the sensor after hitting an object. After the sound wave reaches the sensor, the echo pin goes LOW (falling edge). Thus, by measuring the time between rising edge and falling edge of the echo pin, it’s possible to find the distance of the sensor to an object.

Soft. Tools	Function
TIMER0	It's a delay timer to measure the time of 10 microsecond pulses.
TIMER1	It's used to calculate the time between the rising and falling edge
UART5	It is used to connect TM4C123 to PC sending the distance value.

Pinout	Function
PB4 pin	It connects the TRIGGER.
PB6 pin	It connects the ECCHO.
PE4 pin	UART5 RX
PE5 pin	UART5 TX

Project's file: Ultrasonic_sensor

2.3 FreeRTOS Queue Processing

The application has 6 commands that the user can send from PC via UART to STM32F407:

Command	Function
LED_ON	turn on a LED
LED_OFF	turn off a LED
LED_TOGGLE	turn on toggle a LED
LED_TOGGLE_OFF	turn off toggle a LED
LED_READ_STATUS	read status of a LED
RTC_PRINT_DATETIME	print datetime

under construction...

2.4 Frequency Measurement by TM4C123 of signal comming from Arduino

In this small project the arduino sends a signal to TM4C123 and it calculate the frequency of it sending it to PV via UART. To do, so it measure the time difference between the rising and falling edge using TIMER0 module, that is the period. The frequecy is just the inverse of the period.

Soft. Tools	Function
TIMER0	It's used to calculate the time between rising and falling edge
UART5	It is used to connect TM4C123 to the PC.

Pinout	Function
PE4 pin	UART5 RX
PE5 pin	UART5 TX

File: Frequency_measurement

It's based on the book:

ARM-Based Microcontroller Multitasking Projects Using the FreeRTOS

It's based on courses: