52.3.5 UART Status Register 1 (UARTx_S1)
The S1 register provides inputs to the MCU for generation of UART interrupts or DMA
requests. This register can also be polled by the MCU to check the status of these bits. To
clear a flag, the status register should be read followed by a read or write (depending on
interrupt flag type) to the UART Data Register. Other instructions can be executed
between the two steps as long as it does not compromise the handling of I/O, but the
order of operations is important for flag clearing. When a flag is configured to trigger a
DMA request, assertion of the associated DMA done signal from the DMA controller,
clears the flag.
NOTE
If the condition that results in the assertion of the flag, interrupt
or DMA request is not resolved prior to clearing the flag, the
flag (and interrupt/DMA request) will reassert. For example, if
the DMA or interrupt service routine failed to write sufficient
data to the transmit buffer to raise it above the watermark level,
the flag will reassert and generate another interrupt or DMA
request.
NOTE
Reading an empty data register to clear one of these flags
causes the FIFO pointers to get out of alignment. A receive
FIFO flush reinitializes the pointers.
Addresses: UART0_S1 is 4006_A000h base + 4h offset = 4006_A004h
UART1_S1 is 4006_B000h base + 4h offset = 4006_B004h
UART2_S1 is 4006_C000h base + 4h offset = 4006_C004h
UART3_S1 is 4006_D000h base + 4h offset = 4006_D004h
UART4_S1 is 400E_A000h base + 4h offset = 400E_A004h
UART5_S1 is 400E_B000h base + 4h offset = 400E_B004h
Bit
7
6
5
4
3
2
1
0
Read
Write
Reset
1
1
0
0
0
0
0
0
UARTx_S1 field descriptions
Field
Description
7
TDRE
Transmit Data Register Empty Flag
TDRE will set when the number of datawords in the transmit buffer (D and C3[T8])is equal to or less than
the number indicated by TWFIFO[TXWATER]. A character that is in the process of being transmitted is
not included in the count. To clear TDRE, read S1 when TDRE is set and then write to the UART data
Table continues on the next page...
Chapter 52 Universal Asynchronous Receiver/Transmitter (UART)
K53 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.
1441
Содержание K53 Series
Страница 2: ...K53 Sub Family Reference Manual Rev 6 Nov 2011 2 Freescale Semiconductor Inc...
Страница 58: ...K53 Sub Family Reference Manual Rev 6 Nov 2011 58 Freescale Semiconductor Inc...
Страница 70: ...Orderable part numbers K53 Sub Family Reference Manual Rev 6 Nov 2011 70 Freescale Semiconductor Inc...
Страница 168: ...Human machine interfaces HMI K53 Sub Family Reference Manual Rev 6 Nov 2011 168 Freescale Semiconductor Inc...
Страница 206: ...Boot K53 Sub Family Reference Manual Rev 6 Nov 2011 206 Freescale Semiconductor Inc...
Страница 218: ...Security Interactions with other Modules K53 Sub Family Reference Manual Rev 6 Nov 2011 218 Freescale Semiconductor Inc...
Страница 342: ...PMC Memory Map Register Definition K53 Sub Family Reference Manual Rev 6 Nov 2011 342 Freescale Semiconductor Inc...
Страница 362: ...Functional description K53 Sub Family Reference Manual Rev 6 Nov 2011 362 Freescale Semiconductor Inc...
Страница 384: ...Initialization application information K53 Sub Family Reference Manual Rev 6 Nov 2011 384 Freescale Semiconductor Inc...
Страница 406: ...Application Information K53 Sub Family Reference Manual Rev 6 Nov 2011 406 Freescale Semiconductor Inc...
Страница 424: ...Functional Description K53 Sub Family Reference Manual Rev 6 Nov 2011 424 Freescale Semiconductor Inc...
Страница 514: ...Initialization application information K53 Sub Family Reference Manual Rev 6 Nov 2011 514 Freescale Semiconductor Inc...
Страница 524: ...Functional Description K53 Sub Family Reference Manual Rev 6 Nov 2011 524 Freescale Semiconductor Inc...
Страница 546: ...Restrictions on Watchdog Operation K53 Sub Family Reference Manual Rev 6 Nov 2011 546 Freescale Semiconductor Inc...
Страница 594: ...Interrupts K53 Sub Family Reference Manual Rev 6 Nov 2011 594 Freescale Semiconductor Inc...
Страница 628: ...Functional description K53 Sub Family Reference Manual Rev 6 Nov 2011 628 Freescale Semiconductor Inc...
Страница 702: ...Flash Operation in Low Power Modes K53 Sub Family Reference Manual Rev 6 Nov 2011 702 Freescale Semiconductor Inc...
Страница 772: ...Functional description K53 Sub Family Reference Manual Rev 6 Nov 2011 772 Freescale Semiconductor Inc...
Страница 808: ...Initialization Application Information K53 Sub Family Reference Manual Rev 6 Nov 2011 808 Freescale Semiconductor Inc...
Страница 864: ...Application information K53 Sub Family Reference Manual Rev 6 Nov 2011 864 Freescale Semiconductor Inc...
Страница 894: ...DAC Interrupts K53 Sub Family Reference Manual Rev 6 Nov 2011 894 Freescale Semiconductor Inc...
Страница 908: ...Functional Description K53 Sub Family Reference Manual Rev 6 Nov 2011 908 Freescale Semiconductor Inc...
Страница 920: ...Functional Description K53 Sub Family Reference Manual Rev 6 Nov 2011 920 Freescale Semiconductor Inc...
Страница 926: ...Functional Description K53 Sub Family Reference Manual Rev 6 Nov 2011 926 Freescale Semiconductor Inc...
Страница 1092: ...FTM Interrupts K53 Sub Family Reference Manual Rev 6 Nov 2011 1092 Freescale Semiconductor Inc...
Страница 1114: ...Functional description K53 Sub Family Reference Manual Rev 6 Nov 2011 1114 Freescale Semiconductor Inc...
Страница 1156: ...Functional description K53 Sub Family Reference Manual Rev 6 Nov 2011 1156 Freescale Semiconductor Inc...
Страница 1304: ...On The Go Operation K53 Sub Family Reference Manual Rev 6 Nov 2011 1304 Freescale Semiconductor Inc...
Страница 1334: ...USB Voltage Regulator Module Signal Descriptions K53 Sub Family Reference Manual Rev 6 Nov 2011 1334 Freescale Semiconductor Inc...
Страница 1388: ...Initialization Application Information K53 Sub Family Reference Manual Rev 6 Nov 2011 1388 Freescale Semiconductor Inc...
Страница 1514: ...Application information K53 Sub Family Reference Manual Rev 6 Nov 2011 1514 Freescale Semiconductor Inc...
Страница 1622: ...Software restrictions K53 Sub Family Reference Manual Rev 6 Nov 2011 1622 Freescale Semiconductor Inc...
Страница 1694: ...Initialization application information K53 Sub Family Reference Manual Rev 6 Nov 2011 1694 Freescale Semiconductor Inc...
Страница 1704: ...Functional description K53 Sub Family Reference Manual Rev 6 Nov 2011 1704 Freescale Semiconductor Inc...
Страница 1734: ...Application information K53 Sub Family Reference Manual Rev 6 Nov 2011 1734 Freescale Semiconductor Inc...
Страница 1800: ...Application information K53 Sub Family Reference Manual Rev 6 Nov 2011 1800 Freescale Semiconductor Inc...
Страница 1822: ...K53 Sub Family Reference Manual Rev 6 Nov 2011 1822 Freescale Semiconductor Inc...