/* configure the peripheral clock prescaler in USART IrDA low-power mode  */
void usart_prescaler_config(uint32_t usart_periph, uint8_t psc)
/* configure the peripheral clock prescaler in USART IrDA low-power mode  */
void usart_prescaler_config(uint32_t usart_periph, uint8_t psc)
{
    USART_GP(usart_periph) &= ~(USART_GP_PSC);
    USART_GP(usart_periph) |= (uint32_t)psc;
}