Enabled writing to UART.

emb/uart.cpp

@@ -12,7 +12,6 @@ void initUart()
     
     UCSR0A = (1 << U2X0);  // double transmission speed
     UCSR0B = (1 << RXCIE0) // enable RX complete interrupt
-           | (1 << UDRIE0) // enable data register empty interrupt
            | (1 << RXEN0)  // enable receiver
            | (1 << TXEN0); // enable transmitter
     UCSR0C = (0 << UMSEL01) | (0 << UMSEL00) // asynchronous USART
@@ -25,12 +24,14 @@ void initUart()
     sei();
 }
 
-ISR(USART_RX_vect)
+void writeUart(uint8_t value)
 {
-    uart_add_ch(UDR0);
+    while (!(UCSR0A & (1 << UDRE0)));
+    
+    UDR0 = value;
 }
 
-ISR(USART_UDRE_vect)
+ISR(USART_RX_vect)
 {
-    // nothing to do right now
+    uart_add_ch(UDR0);
 }

emb/uart.hpp

 #ifndef UART_H
 #define UART_H
 
+#include <stdint.h>
+
 /**
  * Initialises the UART logic.
  */
 void initUart();
 
+/**
+ * Writes a character to the UART port.
+ */
+void writeUart(uint8_t value);
+
 #endif /* UART_H */