46.3.28 UART 7816 Wait FD Register (UARTx_WF7816)
The WF7816 contains parameters that are used in the generation of various counters
including GT, CGT, BGT, WT, and BWT. This register may be read at any time. This
register must be written to only when C7816[ISO_7816E] is not set.
Address: Base a 1Dh offset
Bit
7
6
5
4
3
2
1
0
Read
Write
Reset
0
0
0
0
0
0
0
1
UARTx_WF7816 field descriptions
Field
Description
7–0
GTFD
FD Multiplier
Used as another multiplier in the calculation of BWT. This value represents a number between 1 and 255.
The value of 0 is invalid. This value is not used in baud rate generation. See
.
46.3.29 UART 7816 Error Threshold Register (UARTx_ET7816)
The ET7816 register contains fields that determine the number of NACKs that must be
received or transmitted before the host processor is notified. This register may be read at
anytime. This register must be written to only when C7816[ISO_7816E] is not set.
Address: Base a 1Eh offset
Bit
7
6
5
4
3
2
1
0
Read
Write
Reset
0
0
0
0
0
0
0
0
UARTx_ET7816 field descriptions
Field
Description
7–4
TXTHRESHOLD
Transmit NACK Threshold
The value written to this field indicates the maximum number of failed attempts (NACKs) a transmitted
character can have before the host processor is notified. This field is meaningful only when
C7816[TTYPE] = 0 and C7816[ANACK] = 1. The value read from this field represents the number of
consecutive NACKs that have been received since the last successful transmission. This counter
saturates at 4'hF and does not wrap around. Regardless of how many NACKs that are received, the
UART continues to retransmit indefinitely. This flag only asserts when C7816[TTYPE] = 0. For additional
information see the IS7816[TXT] field description.
0
TXT asserts on the first NACK that is received.
1
TXT asserts on the second NACK that is received.
Table continues on the next page...
Chapter 46 Universal Asynchronous Receiver/Transmitter (UART)
K22F Sub-Family Reference Manual , Rev. 3, 7/2014
Freescale Semiconductor, Inc.
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