added uart module

include/bits.h

@@ -13,4 +13,8 @@
 #define SET_OUTPUT(port, pin) SET_BIT(port, pin)
 #define SET_INPUT(port, pin) CLR_BIT(port, pin)
 
+// makes pin 4 of port B a pull up resistor
+// example: PULL_UP_RESISTOR(DDRB, PORTB, DDB4)
+#define PULL_UP_RESISTOR(port, output, pin) CLR_BIT(port, pin); SET_BIT(output, pin)
+
 #endif //ARDUINO_BITS_H

include/prelude.h

@@ -15,5 +15,6 @@
 // custom header files
 #include "bits.h"
 #include "interrupt.h"
+#include "uart.h"
 
 #endif //ARDUINO_PRELUDE_H

include/uart.h

@@ -0,0 +1,25 @@
+//
+// Created by servostar on 09.12.23.
+//
+
+#ifndef ARDUINO_UART_H
+#define ARDUINO_UART_H
+
+#include "prelude.h"
+
+#include <stddef.h>
+#include <inttypes.h>
+
+void uart_init(uint16_t baud);
+
+uint8_t uart_read();
+
+void uart_read(uint8_t* buffer, size_t size);
+
+void uart_write(uint8_t frame);
+
+void uart_write_bytes(const uint8_t* buffer, size_t bytes);
+
+void uart_write_string(const char* string);
+
+#endif //ARDUINO_UART_H

platformio.ini

@@ -21,4 +21,5 @@ build_src_filter =
     -<button_poll/>
     -<trafficlight/>
     -<summer/>
-    +<summer_controlled/>
+    -<summer_controlled/>
+    +<uart/>

src/main.cpp

@@ -7,7 +7,8 @@ extern void loop();
 //#include "button_interupt/button.h"
 //#include "trafficlight/trafficlight.h"
 //#include "summer/summer.h"
-#include "summer_controlled/summer.h"
+//#include "summer_controlled/summer.h"
+#include "uart/uart_read_write.h"
 
 int main() {
     init();

src/uart.cpp

@@ -0,0 +1,49 @@
+//
+// Created by servostar on 09.12.23.
+//
+
+#include "uart.h"
+
+void uart_init(uint16_t baud) {
+    uint16_t ubrr = F_CPU / 16 / baud - 1;
+
+    UBRR0H = (uint8_t) (ubrr >> 8);
+    UBRR0L = (uint8_t) (ubrr & 0xFF);
+
+    UCSR0B |= (1 << RXEN0) | (1 << TXEN0);  // enable receiver and transmitter
+    UCSR0C |= (1 << UCSZ01) | (3 << UCSZ00); // set frame: 8 bit
+    UCSR0C &= ~(1 << USBS0); // 1 stop bit
+
+    UCSR0B |= (1 << RXCIE0); // enable receiver interrupt
+}
+
+void uart_write(uint8_t frame) {
+    // wait until TX is free
+    while (!(UCSR0A & (1 << UDRE0)));
+    // write data
+    UDR0 = frame;
+}
+
+uint8_t uart_read() {
+    // wait until RX is free
+    while (!(UCSR0A & (1 << RXC0)));
+    // read data
+    return UDR0;
+}
+
+void uart_read_bytes(uint8_t* buffer, size_t size) {
+    for (size_t i = 0; i < size; i++) {
+        buffer[i] = uart_read();
+    }
+}
+
+void uart_write_bytes(uint8_t* buffer, size_t bytes) {
+    for (size_t i = 0; i < bytes; i++) {
+        uart_write(buffer[i]);
+    }
+}
+
+void uart_write_string(const char* string) {
+    while(*string)
+        uart_write(*string++);
+}

src/uart/uart_read_write.cpp

@@ -0,0 +1,21 @@
+//
+// Created by servostar on 09.12.23.
+//
+
+#include "uart_read_write.h"
+
+#include "uart.h"
+
+#define BAUD 9600
+
+ISR (USART_RX_vect)
+{
+    uart_write_string("Hello, World!\n");
+}
+
+void init() {
+    uart_init(BAUD);
+}
+
+void loop() {
+}

src/uart/uart_read_write.h

@@ -0,0 +1,13 @@
+//
+// Created by servostar on 09.12.23.
+//
+
+#ifndef ARDUINO_UART_READ_WRITE_H
+#define ARDUINO_UART_READ_WRITE_H
+
+#include "prelude.h"
+
+void init();
+void loop();
+
+#endif // ARDUINO_UART_READ_WRITE_H