backspace works

module02/ex00/main.c

@@ -104,7 +104,8 @@ void uart_tx(char c) {
 	UDR0 = (unsigned char) c;													// 20.11.1 : Put data into buffer, UDRn – USART I/O Data Register (read and write)
 }
 
-// screen /dev/ttyUSB0 115200
+// write Z on serial port, at a !Hz frequency
+// `screen /dev/ttyUSB0 115200`
 int main() {
 	uart_init();
 	while (1) {

module02/ex01/main.c

@@ -134,7 +134,7 @@ void uart_printstr(const char* str) {
 	}
 }
 
-// print hello world, on serial port, every 2 seconds, with empty infinite loop
+// print "Hello World!\n", on serial port, every 2 seconds, with empty infinite loop
 // `screen /dev/ttyUSB0 115200`
 int main() {
 	uart_init();
@@ -154,5 +154,5 @@ int main() {
 
 // ISR interrupt macro : https://www.nongnu.org/avr-libc/user-manual/group__avr__interrupts.html
 ISR(TIMER1_COMPA_vect) {							// Table 12-7 : we select the code for timer 1 on channel A
-	uart_printstr("Hello World!");
+	uart_printstr("Hello World!\r\n");				// \n and \r : https://stackoverflow.com/questions/7812142/how-to-toggle-cr-lf-in-gnu-screen
 }

module02/ex04/main.c

@@ -142,7 +142,13 @@ void uart_tx(char c) {
 ISR(USART_RX_vect) {																// Table 12-7 : we select the code for USART Receive
 	// char received_char = uart_rx();
 	char received_char = UDR0;				// Read received character
+	if (received_char == '\b' || received_char == 127) {  // If backspace is received
+		uart_tx('\b');  // Move cursor back
+		uart_tx(' ');   // Erase the character on screen
+		uart_tx('\b');  // Move cursor back again
+	} else {
 		uart_tx(SWITCH_CASE(received_char)); // Toggle case and send back
+	}
 }
 
 // send back caracters received on serial port with case toggling, using interupt and empty infinite loop