/* USART Transmitter DMA Enable. 
DMA is available on:  */
void usart_enable_tx_dma(uint32_t usart)
/* USART Transmitter DMA Enable. 
DMA is available on:  */
void usart_enable_tx_dma(uint32_t usart)
{
	USART_CR3(usart) |= USART_CR3_DMAT;
}