UARTx_C5 field descriptions (continued)Field Description0 If C2[RIE] and S1[RDRF] are set, the RDFR interrupt request signal is asserted to request an interruptservice.1 If C2[RIE] and S1[RDRF] are set, the RDRF DMA request signal is asserted to request a DMAtransfer.4ReservedThis field is reserved.This read-only field is reserved and always has the value 0.Reserved This field is reserved.This read-only field is reserved and always has the value 0.38.4.13 UART 7816 Control Register (UARTx_C7816)The C7816 register is the primary control register for ISO-7816 specific functionality.This register is specific to 7816 functionality and the values in this register have no effecton UART operation and should be ignored if ISO_7816E is not set/enabled. This registermay be read at any time but values must be changed only when ISO_7816E is not set.Address: 4006_C000h base + 18h offset = 4006_C018hBit 7 6 5 4 3 2 1 0Read 0 ONACK ANACK INIT TTYPE ISO_7816EWriteReset 0 0 0 0 0 0 0 0UARTx_C7816 field descriptionsField Description7–5ReservedThis field is reserved.This read-only field is reserved and always has the value 0.4ONACKGenerate NACK on OverflowWhen this field is set, the receiver automatically generates a NACK response if a receive buffer overrunoccurs, as indicated by S1[OR]. In many systems, this results in the transmitter resending the packet thatoverflowed until the retransmit threshold for that transmitter is reached. A NACK is generated only ifTTYPE=0. This field operates independently of ANACK. See . Overrun NACK considerations0 The received data does not generate a NACK when the receipt of the data results in an overflowevent.1 If the receiver buffer overflows, a NACK is automatically sent on a received character.3ANACKGenerate NACK on ErrorWhen this field is set, the receiver automatically generates a NACK response if a parity error occurs or ifINIT is set and an invalid initial character is detected. A NACK is generated only if TTYPE = 0. If ANACK isset, the UART attempts to retransmit the data indefinitely. To stop retransmission attempts, clear C2[TE]or ISO_7816E and do not set until S1[TC] sets C2[TE] again.Table continues on the next page...Memory map and registersKL27 Sub-Family Reference Manual , Rev. 5, 01/2016696 Freescale Semiconductor, Inc.
