Information

UARTx_IS7816 field descriptions (continued)
Field Description
0 A valid initial character has not been received.
1 A valid initial character has been received.
3
Reserved
This field is reserved.
This read-only field is reserved and always has the value 0.
2
GTV
Guard Timer Violated Interrupt
Indicates that one or more of the character guard time, block guard time, or guard time are violated. This
interrupt is cleared by writing 1.
0 A guard time (GT, CGT, or BGT) has not been violated.
1 A guard time (GT, CGT, or BGT) has been violated.
1
TXT
Transmit Threshold Exceeded Interrupt
Indicates that the transmit NACK threshold has been exceeded as indicated by ET7816[TXTHRESHOLD].
Regardless of whether this flag is set, the UART continues to retransmit indefinitely. This flag asserts only
when C7816[TTYPE] = 0. If 7816E is cleared/disabled, ANACK is cleared/disabled, C2[TE] is cleared/
disabled, C7816[TTYPE] = 1, or packet is transferred without receiving a NACK, the internal NACK
detection counter is cleared and the count restarts from zero on the next received NACK. This interrupt is
cleared by writing 1.
0 The number of retries and corresponding NACKS does not exceed the value in
ET7816[TXTHRESHOLD].
1 The number of retries and corresponding NACKS exceeds the value in ET7816[TXTHRESHOLD].
0
RXT
Receive Threshold Exceeded Interrupt
Indicates that there are more than ET7816[RXTHRESHOLD] consecutive NACKS generated in response
to parity errors on received data. This flag requires ANACK to be set. Additionally, this flag asserts only
when C7816[TTYPE] = 0. Clearing this field also resets the counter keeping track of consecutive NACKS.
The UART will continue to attempt to receive data regardless of whether this flag is set. If 7816E is
cleared/disabled, RE is cleared/disabled, C7816[TTYPE] = 1, or packet is received without needing to
issue a NACK, the internal NACK detection counter is cleared and the count restarts from zero on the next
transmitted NACK. This interrupt is cleared by writing 1.
0 The number of consecutive NACKS generated as a result of parity errors and buffer overruns is less
than or equal to the value in ET7816[RXTHRESHOLD].
1 The number of consecutive NACKS generated as a result of parity errors and buffer overruns is
greater than the value in ET7816[RXTHRESHOLD].
48.3.26 UART 7816 Wait Parameter Register (UARTx_WP7816T0)
The WP7816 register contains constants used in the generation of various wait timer
counters. To save register space, this register is used differently when C7816[TTYPE] =
0 and C7816[TTYPE] = 1. This register may be read at any time. This register must be
written to only when C7816[ISO_7816E] is not set.
Address: Base address + 1Bh offset
Bit 7 6 5 4 3 2 1 0
Read
WI
Write
Reset
0 0 0 0 1 0 1 0
Chapter 48 Universal Asynchronous Receiver/Transmitter (UART)
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
Freescale Semiconductor, Inc.
Preliminary
1307
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