From 40213592300e230305ae564dfc931cb224a1f580 Mon Sep 17 00:00:00 2001
From: _N0x <tf@n0x.io>
Date: Sat, 4 Dec 2021 23:11:51 +0100
Subject: [PATCH] Fixed issues with UART and added proper interupts

---
 EmbeddedSystemsTHM/UART.c | 188 ++++++++++++++++++++++----------------
 EmbeddedSystemsTHM/UART.h |  22 ++---
 2 files changed, 118 insertions(+), 92 deletions(-)

diff --git a/EmbeddedSystemsTHM/UART.c b/EmbeddedSystemsTHM/UART.c
index b897129..bf22af6 100644
--- a/EmbeddedSystemsTHM/UART.c
+++ b/EmbeddedSystemsTHM/UART.c
@@ -1,106 +1,132 @@
 /*
  * UART.c
  *
- * Created: 18/11/2021 17:13:25
+ * Created: 25/11/2021 16:26:10
  *  Author: n0x
  */ 
 
-#include <avr/io.h>
-#include <avr/interrupt.h>
-#include <string.h>
 #include "UART.h"
 
-volatile int enabled = 1;
+#define SIZE_BUFFER 500
+struct CircularBuffer{
+	volatile char data[SIZE_BUFFER];
+	volatile uint16_t Readpointer;
+	volatile uint16_t Writepointer;
+};
+
+struct CircularBuffer TxBuffer;
+struct CircularBuffer RxBuffer;
+volatile uint8_t TxActive;
 
-/*	Schreiben Sie eine Funktion, welche die UART Schnittstelle für das Senden von
-	Daten mit 
-		9600Baud, 
-		8 Bit,
-		keine Parität und 
-		1 Stopbit 
-	initialisiert. */
 void 
 uart_init(void)
 {
-	/* set BAUD rate to 9600 */
- 	UBRR0 = 103;
- 	
-	/* Async UART */
-	UCSR0C |= (0<<UMSEL00)|(0<<UMSEL01);
+	
+	UBRR0 = 103;					/* set BAUD rate to 9600 */
 	 
- 	/* Disable Parity */
- 	UCSR0C |= (0<<UPM00)|(0<<UPM01);
-	 
-	/* 8 Bit */
-	UCSR0C |= (1<<UCSZ00)|(1<<UCSZ01);
+	UCSR0C |= 
+	(0<<UMSEL00)|(0<<UMSEL01)|		/* Async UART */
+	(0<<UPM00)|(0<<UPM01)|			/* Disable Parity */
+	(1<<UCSZ00)|(1<<UCSZ01)|		/* 8 Bit */
+	(0<<USBS0);						/* 1 Stopbit */
+	 	
 	
-	/* 1 Stopbit */
-	UCSR0C |= (0<<USBS0);
+	UCSR0B |= 
+	(1<<TXEN0)|(1<<RXEN0)|			/* enable send and receive */
+	(1<<RXCIE0);					/* enable Receive interrupts */	
 	
-	/* enable send */
-	UCSR0B = (1<<TXEN0);
+	TxBuffer.Readpointer = 0;
+	TxBuffer.Writepointer = 0;
+	RxBuffer.Readpointer = 0;
+	RxBuffer.Writepointer = 0;
 }
 
-/*	Schreiben Sie eine Funktion, welche einen String übergeben bekommt, und diesen
-	auf der UART Schnittstelle ausgibt. */
-void 
-uart_send (char* string){
-	
-	int len = strlen(string);
+/* ------------------------ */
+/*       Sending Data       */
+/* ------------------------ */
 
-	for(int i = 0; i < len; i++){
-		while (!( UCSR0A & (1<<UDRE0)) );
-		UDR0 = string[i];
-	}
-}
-
-/* Schreiben Sie eine Funktion, welche die UART Schnittstelle für das Senden von Daten mit 
-		9600Baud, 
-		8 Bit, 
-		keine Parität und 
-		1 Stoppbit 
-	initialisiert. Nutzen Sie dabei ein Uart-Interrupt. */
-void 
-uart_init_isr(void)
-{
-	/* set BAUD rate to 9600 */
-	UBRR0 = 103;
-	 	
-	/* Async UART */
-	UCSR0C |= (0<<UMSEL00)|(0<<UMSEL01);
-	 	
-	/* Disable Parity */
-	UCSR0C |= (0<<UPM00)|(0<<UPM01);
-	 	
-	/* 8 Bit */
-	UCSR0C |= (1<<UCSZ00)|(1<<UCSZ01);
-	 	
-	/* 1 Stopbit */
-	UCSR0C |= (0<<USBS0);
-	 	
-	/* enable send */
-	UCSR0B |= (1<<TXEN0);
-	
-	/* enable interrupt */
-	UCSR0B |= (1<<UDRIE0);	
-}
-
-
-/*	Schreiben Sie eine Funktion, welche einen String übergeben bekommt, und diesen
-	auf der UART Schnittstelle ausgibt. (Interrupts) */
 void
-uart_send_isr(char* string)
+uart_send_string(char* string)
 {
 	int i = 0;
-	while( i < strlen(string)){
-		if(enabled){
-			UDR0 = string[i];
-			i++;
-			enabled = 0;
-		}
+	while(string[i] != '\0'){
+		uart_send_byte(string[i]);
+		i++;
 	}
 }
 
-ISR(USART0_UDRE_vect){
-	enabled = 1;
+void
+uart_send_byte(char c)
+{
+	UCSR0B&=~(1<<TXCIE0);
+	
+	if(TxActive){
+		TxBuffer.data[TxBuffer.Writepointer++] = c;
+		if (TxBuffer.Writepointer>=SIZE_BUFFER){
+			TxBuffer.Writepointer = 0;
+		}
+	} else {
+		TxActive = 1;
+		UDR0 = c;	
+	}
+	UCSR0B |= (1<<TXCIE0);
+}
+
+ISR(USART0_TX_vect)
+{	
+	if(TxBuffer.Readpointer != TxBuffer.Writepointer)
+	{
+		UDR0 = TxBuffer.data[TxBuffer.Readpointer++];
+		
+		if(TxBuffer.Readpointer >= SIZE_BUFFER){
+			TxBuffer.Readpointer = 0;
+		}
+	} else {
+		TxActive = 0;
+	}
+}
+
+/* ------------------------ */
+/*      Receiving Data      */
+/* ------------------------ */
+
+uint8_t 
+uart_data_available(void) 
+{
+	uint8_t dataAvailabel = 0;
+	UCSR0B &= ~(1<<RXCIE0);
+	if(RxBuffer.Readpointer != RxBuffer.Writepointer){
+		dataAvailabel = 1;
+	}
+	UCSR0B |= (1<<RXCIE0);
+	return dataAvailabel;
+}
+
+char 
+uart_get_data(void)
+{
+	char data = 0;
+	UCSR0B &= ~(1<<RXCIE0);
+	if(RxBuffer.Readpointer != RxBuffer.Writepointer)
+	{
+		data = RxBuffer.data[RxBuffer.Readpointer++];
+		if(RxBuffer.Readpointer >= SIZE_BUFFER){
+			RxBuffer.Readpointer = 0;
+		}
+	}
+	UCSR0B |= (1<<RXCIE0);
+	return data;
+}
+
+ISR(USART0_RX_vect)
+{
+	uint8_t status = UCSR0A;
+	uint8_t data = UDR0;
+	
+	if((status & ((1<<DOR0) | (1>>FE0))) == 0){
+		RxBuffer.data[RxBuffer.Writepointer++] = data;
+		if(RxBuffer.Writepointer >= SIZE_BUFFER) {
+			RxBuffer.Writepointer = 0;
+		}
+	}
 }
\ No newline at end of file
diff --git a/EmbeddedSystemsTHM/UART.h b/EmbeddedSystemsTHM/UART.h
index 3483cfb..195815d 100644
--- a/EmbeddedSystemsTHM/UART.h
+++ b/EmbeddedSystemsTHM/UART.h
@@ -1,21 +1,21 @@
 /*
- * UART.h
+ * UART2.h
  *
- * Created: 18/11/2021 17:13:16
+ * Created: 25/11/2021 16:25:59
  *  Author: n0x
  */ 
 
+#include <avr/io.h>
+#include <avr/interrupt.h>
 
-#ifndef UART_H_
-#define UART_H_
+#ifndef UART2_H_
+#define UART2_H_
 
 void uart_init(void);
-void uart_send(char* string);
+void uart_send_byte(char c);
+void uart_send_string(char* string);
 
+uint8_t uart_data_available(void);
+char uart_get_data(void);
 
-void uart_init_isr(void);
-void uart_send_isr(char* string);
-
-int checkIfBlocked(void);
-
-#endif /* UART_H_ */
\ No newline at end of file
+#endif /* UART2_H_ */
\ No newline at end of file