wip

src/usart.h

@@ -16,6 +16,15 @@ struct usart {
 #define USART2_BASE_ADDR (0x40004400U)
 #define USART2 ((struct usart *) USART2_BASE_ADDR)
 
+// SR Register
+// Transmission data register empty
+#define USART_SR_TXE_BIT 7
+#define USART_SR_TXE_TRANSMITTED (1 << USART_SR_TXE_BIT)
+
+// Read data register not empty
+#define USART_SR_RXNE_BIT 5
+#define USART_SR_RXNE_READY (1 <<USART_SR_RXNE_BIT)
+
 // CR Register
 // Oversampling mode
 #define USART_CR1_OVER8_BIT 15
@@ -43,4 +52,6 @@ struct usart {
 void usart2_init(void);
 void usart2_start(void);
 
+void usart2_write_byte(char byte);
+
 #endif