K60P100M100SF2RM Datasheet, PDF (1522/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Memory map and registers
UARTx_WF7816 field descriptions
Field
7–0
GTFD
FD Multiplier
Description
This field is used as another multiplier in the calculation of WT and BWT. This values represents a
number between 1 and 255. The value of 0 is invalid. This value is NOT used in baud rate generation.
See Wait time and guard time parameters and Baud rate generation.
51.3.30 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 only be written when C7816[ISO_7816E] is not set.
Addresses: UART0_ET7816 is 4006_A000h base + 1Eh offset = 4006_A01Eh
UART1_ET7816 is 4006_B000h base + 1Eh offset = 4006_B01Eh
UART2_ET7816 is 4006_C000h base + 1Eh offset = 4006_C01Eh
UART3_ET7816 is 4006_D000h base + 1Eh offset = 4006_D01Eh
UART4_ET7816 is 400E_A000h base + 1Eh offset = 400E_A01Eh
Bit
7
6
5
4
Read
Write
TXTHRESHOLD
Reset
0
0
0
0
3
2
1
0
RXTHRESHOLD
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. Meaning a value of 0 will always result in TXT
asserting on the first NACK that is received. A value of 1 will result in TXT being asserted on the second
NACK that is received. This field is only meaningful 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 will continue to retransmit indefinitely. This
flag only asserts when C7816[TTYPE] = 0. For additional information see the IS7816[TXT] bit description.
3–0
Receive NACK Threshold
RXTHRESHOLD
The value written to this field indicates the maximum number of consecutive NACKs generated as a result
of a parity error or receiver buffer overruns before the host processor is notified. Once the counter
exceeds that value in the field the IS7816[RXT] will be asserted. This field is only meaningful when
C7816[TTYPE] = 0. The value read from this field represents the number of consecutive NACKs that have
been transmitted since the last successful reception. This counter saturates at 4'hF and does not wrap
around. Regardless of the number of NACKs sent, the UART will continue to receive valid packets
indefinitely. For additional information see IS7816[RXT] bit description.
1522
K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.