
S E R I A L C O N T R O L M O D U L E : U A R T
Hardware-based flow control
388
Hardware Reference NS9215
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H a r d w a r e - b a s e d f l o w c o n t r o l
The UART module provides expanded functionality for hardware-based flow control.
The RTS signal normally indicates the state of the receive FIFO. The CTS signal
normally halts the transmitter. With this UART module, the RI, CTS, DCD, or DSR
signals can halt the transmitter. Program these features using the HWFLOW bits in
the Wrapper Configuration register.
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C h a r a c t e r - b a s e d f l o w c o n t r o l ( X O N / X O F F )
Traditional character-based flow control requires the processor to match the flow
control characters and control the transmitter accordingly. This UART module
performs the character matching function in hardware and automatically updates
the state of the transmitter, which allows character-based flow control to achieve
the same response time as hardware-based flow control.
Example
configuration
Configure the character-based flow control using at least two Receive Character
Match registers and the Receive Character-Based Flow Control register. This table
shows a sample configuration for a system transferring 8 data bits per character.
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F o r c e d c h a r a c t e r t r a n s m i s s i o n
UART provides a mechanism in which you can bypass data in the transmit FIFO with
a specific character. The specified character is transmitted after the current
Control register
Field
Value
Comment
Receive Character Match Control
Register 0
ENABLE
1
Enable character match
MASK
0x00
Mask bits
DATA
0x7e
Define character
Receive Character Match Control
Register 1
ENABLE
1
Enable character match
MASK
0x00
Mask bits
DATA
0x81
Define character
Receive Character-Based Flow
Control register
FLOW0
0x2
XON when matched
FLOW1
0x3
XOFF when matched
Содержание NS9215
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Страница 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
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Страница 384: ...I O HU B M OD UL E Module Direct Mode TX Data Last FIFO 384 Hardware Reference NS9215 31 March 2008...
Страница 414: ...S E R I A L C ON T RO L M O D U L E U ART UART Modem Status register 414 Hardware Reference NS9215...
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Страница 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Страница 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
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