# USART

## EC\_HAL for USART

{% embed url="<https://github.com/ykkimhgu/EC-student/tree/main/tutorial-student>" %}

### Header File

`ecUSART.h`

```cpp
#ifndef __EC_USART_H
#define __EC_USART_H

#include <stdio.h>
#include "stm32f411xe.h"
#include "ecGPIO.h"
#include "ecRCC.h"

#define POL 0
#define INT 1

// You can modify this
#define BAUD_9600	9600
#define BAUD_19200	19200
#define BAUD_38400  38400
#define BAUD_57600	57600
#define BAUD_115200 115200
#define BAUD_921600 921600


// ********************** USART 2 (USB) ***************************
	// PA_2 = USART2_TX
	// PA_3 = USART2_RX
	// Alternate function(AF7), High Speed, Push pull, Pull up
	// APB1
// **********************************************************

	// ********************** USART 1 ***************************
	// PA_9 = USART1_TX (default)	// PB_6  (option)
	// PA_10 = USART1_RX (default)	// PB_3 (option)
	// APB2
	// **********************************************************

// ********************** USART 6 ***************************
	// PA_11 = USART6_TX (default)	// PC_6  (option)
	// PA_12 = USART6_RX (default)	// PC_7 (option)
	// APB2
// **********************************************************

// Configuration UART 1, 2 using default pins
void UART1_init(void);
void UART2_init(void);	
void UART1_baud(uint32_t baud);
void UART2_baud(uint32_t baud);

// Configuration USART write & read
void USART1_write(uint8_t* buffer, uint32_t nBytes);
void USART2_write(uint8_t* buffer, uint32_t nBytes);
uint8_t USART1_read(void);										
uint8_t USART2_read(void);	

// Inturrupt USART1,2
uint32_t is_USART1_RXNE(void);
uint32_t is_USART2_RXNE(void);

// private functions
void USART_write(USART_TypeDef* USARTx, uint8_t* buffer, uint32_t nBytes);
void USART_init(USART_TypeDef* USARTx, uint32_t baud);  		
void UART_baud(USART_TypeDef* USARTx, uint32_t baud);											
uint32_t is_USART_RXNE(USART_TypeDef * USARTx);
uint8_t USART_read(USART_TypeDef * USARTx);										
void USART_setting(USART_TypeDef* USARTx, GPIO_TypeDef* GPIO_TX, int pinTX, GPIO_TypeDef* GPIO_RX, int pinRX, uint32_t baud); 
void USART_delay(uint32_t us);  

#endif
```

####

## Example Code

### HAL: USART example1

```cpp
#include "stm32f4xx.h"
#include "ecGPIO.h"
#include "ecRCC.h"
#include "ecUART.h"
#include "ecSysTick.h"


static volatile uint8_t PC_Data = 0;
static volatile uint8_t BT_Data = 0;
uint8_t PC_string[]="Loop:\r\n";

void setup(void){
	RCC_PLL_init();
	SysTick_init();
	
	// USART2: USB serial init
	UART2_init();
	UART2_baud(BAUD_9600);

	// USART1: BT serial init 
	UART1_init();
	UART1_baud(BAUD_9600);
}

int main(void){	
	setup();
	printf("MCU Initialized\r\n");	
	while(1){
		// USART Receive: Use Interrupt only
		// USART Transmit:  Interrupt or Polling
		USART2_write(PC_string, 7);
		delay_ms(2000);        
	}
}

void USART2_IRQHandler(){          		// USART2 RX Interrupt : Recommended
	if(is_USART2_RXNE()){
		PC_Data = USART2_read();		// RX from UART2 (PC)
		USART2_write(&PC_Data,1);		// TX to USART2	 (PC)	 Echo of keyboard typing		
	}
}


void USART1_IRQHandler(){          		// USART2 RX Interrupt : Recommended
	if(is_USART1_RXNE()){
		BT_Data = USART1_read();		// RX from UART1 (BT)		
		printf("RX: %c \r\n",BT_Data); // TX to USART2(PC)
	}
}
```

### HAL: USART example2

```cpp
#include "stm32f4xx.h"
#include "ecGPIO.h"
#include "ecRCC.h"
#include "ecUART.h"
#include "ecSysTick.h"

#define MAX_BUF 	10
#define END_CHAR 	13

static volatile uint8_t buffer[MAX_BUF]={0, };
static volatile uint8_t PC_string[MAX_BUF]={0, };
static volatile uint8_t PC_data = 0;

static volatile int idx = 0;
static volatile int bReceive =0;

void setup(void){
	RCC_PLL_init();
	SysTick_init();
	
	// USART2: USB serial init
	UART2_init();
	UART2_baud(BAUD_9600);

	// USART1: BT serial init 
	UART1_init();
	UART1_baud(BAUD_9600);
}

int main(void){	
	setup();
	printf("MCU Initialized\r\n");	
	
	while(1){
		if (bReceive == 1){
			printf("PC_string: %s\r\n", PC_string);				
			bReceive = 0;
		}
	}
}

void USART2_IRQHandler(){          		// USART2 RX Interrupt : Recommended
	if(is_USART2_RXNE()){
		PC_data = USART2_read();		// RX from UART2 (PC)
		USART2_write(&PC_data,1);		// TX to USART2	 (PC)	 Echo of keyboard typing
		
		// Creates a String from serial character receive				
		if(PC_data != END_CHAR && (idx < MAX_BUF)){	
			buffer[idx] = PC_data;
			idx++;
		}
		else if (PC_data== END_CHAR) {						
			bReceive = 1;
			// reset PC_string;
			memset(PC_string, 0, sizeof(char) * MAX_BUF);
			// copy to PC_string;
			memcpy(PC_string, buffer, sizeof(char) * idx);
			// reset buffer
			memset(buffer, 0, sizeof(char) * MAX_BUF);	
			idx = 0;
		}
		else{				//  if(idx >= MAX_BUF)			
			idx = 0;							
			// reset PC_string;
			memset(PC_string, 0, sizeof(char) * MAX_BUF);
			// reset buffer
			memset(buffer, 0, sizeof(char) * MAX_BUF);	// reset buffer
			printf("ERROR : Too long string\r\n");
		}
	}
}
```

####

#### Tutorial: SysTick Initiation


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