# PreLAB: SysTick

Name:

ID:

## I. Introduction

In this tutorial, we will learn how to use SysTick interrupt. We will create functions to count up numbers at a constant rate using SysTick.

The objectives of this tutorial are how to

* Configure SysTick with NVIC
* Create your own functions for the configuration of interrupts

### Hardware

* NUCLEO -F411RE

### Software

* VS code, CMSIS, EC\_HAL

### Documentation

* [STM32 Reference Manual](https://ykkim.gitbook.io/ec/stm32-m4-programming/hardware/nucleo-f411re#manual-documentation)

## II. Basics of SysTick

### A. Register List

List of SysTick registers for this tutorial. \[**Programming Manual** ch4.3, ch10.2]

![Register List](https://raw.githubusercontent.com/LeeJunjae1/EC_22000573/main/img/systick.png)

### B. Register Setting

**(RCC system clock)**

1. PLL, HCLK= 84MHz

**(System Tick Configuration)**

1. Disable SysTick Timer

`SysTick->CTRL ENABLE=0`

2. Choose clock signal: System clock or ref. clock(STCLK)

`SysTick->CTRL CLKSOURCE = 0 or 1`

3. Choose to use Tick Interrupt (timer goes 1->0)

`SysTick->CTRL TICKINT = 0 or 1`

4. Write reload Counting value (24-bit)

`SysTick->LOAD RELOAD = (value-1)`

5. Start SysTick Timer

`SysTick->CTRL ENABLE=1`

6. (option) Read or Clear current counting value

`Read from SysTick->VAL`

`Write clears value`

**(NVIC Configuration)**

1. NVIC SysTick Interrupt priority
2. NVIC SysTick Enable

***

## III. Tutorial

### A. Programming

This is an example code for turning the LED on/off with the button input trigger with a wait function.

#### Procedure

* Name the project as ‘**TU\_SysTick**’ by creating a new folder as ‘**tutorial/TU\_SysTick**’
* Download the header library files and save under `include\`.
  * `ecSysTick2_student. ecSysTick2_student.c`: [Click here to download](https://github.com/ykkimhgu/EC-student/tree/main/include/lib-student)
  * Rename the files as `ecSysTick2. ecSysTick2.c`
* Download the template code
  * `TU_SysTick_student.c` : [Click here to download](https://github.com/ykkimhgu/EC-student/tree/main/tutorial/tutorial-student)
* This is an example code for turning LED on/off with the button input trigger with a wait function.
* Fill in the empty spaces in the code.
* Run the program and check your result.
* Your tutorial report must be submitted to the LMS
* This is a sample program that turns LED on/off at 1 second period using SysTick

####

#### Example Code

* Understand the code definition for void SysTick\_init() : in `ecSysTick2.h`
* Read the code definition for void delay\_ms( ) in `ecSysTick2.h`
* You can modify previous LAB code to include delay\_ms()

```c
/**
******************************************************************************
* @author  SSSLAB
* @Mod		 2025-9-25 by YKKIM
* @brief   Embedded Controller:  Tutorial ___
*					 - _________________________________
*
******************************************************************************
*/

#include "stm32f411xe.h"
#include "ecRCC2.h"
#include "ecGPIO2.h"
#include "ecSysTick2.h"  // added

volatile uint32_t msTicks = 0;

void setup(void);

void main(void) {	
      // System CLOCK, GPIO Initialiization ----------------------------------------
	setup();

       // While loop ------------------------------------------------------				

	while(1){
                GPIO_write(PB_12, HIGH);        
        	delay_ms (1000);
	        GPIO_write(PB_12, LOW);        
	        delay_ms (1000);        
	}
}




void setup(void)
{
	RCC_PLL_init();              // System Clock = 84MHz	
	//GPIO_init(PA_5, OUTPUT);     // LED for Nucleo
   	GPIO_init(PB_12, OUTPUT);  // LED for Eval Board	JKIT
        SysTick_init(); 
}

```

####