• In transmission, the USART insert

• In transmission, the USART inserts the Guard Time (as programmed in the Guard Timeregister) between two successive characters. As the Guard Time is measured after thestop bit of the previous character, the GT[7:0] register must be programmed to thedesired CGT (Character Guard Time, as defined by the 7816-3 specification) minus 12(the duration of one character).• The assertion of the TC flag can be delayed by programming the Guard Time register.In normal operation, TC is asserted when the transmit shift register is empty and nofurther transmit requests are outstanding. In Smartcard mode an empty transmit shiftregister triggers the Guard Time counter to count up to the programmed value in theGuard Time register. TC is forced low during this time. When the Guard Time counterreaches the programmed value TC is asserted high.• The de-assertion of TC flag is unaffected by Smartcard mode.• If a framing error is detected on the transmitter end (due to a NACK from the receiver),the NACK is not detected as a start bit by the receive block of the transmitter.According to the ISO protocol, the duration of the received NACK can be 1 or 2 baudclock periods.• On the receiver side, if a parity error is detected and a NACK is transmitted the receiverdoes not detect the NACK as a start bit.