/* USART Wait for Received Data Available. 
Blocks until the receive data buffer holds a valid received data word. */
void usart_wait_recv_ready(uint32_t usart)
/* USART Wait for Received Data Available. 
Blocks until the receive data buffer holds a valid received data word. */
void usart_wait_recv_ready(uint32_t usart)
{
	while ((USART_SR(usart) & USART_SR_RXNE) == 0);
}