Description of Operation
15-12
ADSP-BF50x Blackfin Processor Hardware Reference
hardware pauses transmission if the
UARTxCTS
bit is zero. If the
UARTxCTS
input is deasserted, the transmitter still completes transmission of the data
work currently held in the internal
TSRx
register, but does not continue
with the data in
UARTx_THR
. If the
UARTxCTS
is asserted again, the transmit-
ter resumes and loads the content of
UARTx_THR
into
TSRx
.
If the RX handshaking protocol is enabled (bit
ARTS
=1 in the
UARTx_MCR
register), the
UARTxRTS
output pin is toggled automatically by the
receiver's hardware. The pin’s assertion and deassertion timing is con-
trolled by the receive FIFO RTS threshold (
RFRT
) bit in the
UARTx_MCR
register. If
RFRT
is cleared, the
UARTxRTS
pin is deasserted when the receive
buffer already holds two words and a third start bit is detected. The
UARTxRTS
pin is asserted again when the buffer does not contain any more
data than the word in the
UARTx_RBR
register. If
RFRT
is set, the
UARTxRTS
pin is deasserted when the receive buffer already holds four words and a
fifth start bit is detected. The
UARTxRTS
is re-asserted when the buffer con-
tains less than four words. Hardware guarantees minimal
UARTxRTS
deassertion pulse width of at least the number of data bits as defined by
the
WLS
bit field in the
UARTx_LCR
register.
If
ACTS
=0, the TX handshaking protocol is disabled, and the UART trans-
mits data as long as there is data to transmit, regardless of the value of
UARTxCTS
. With
ACTS
=0 software can pause on-going transmission by set-
ting the
XOFF
bit in the
UARTx_MCR
register.
If
ARTS
=0, the
UARTxRTS
pin is not generated automatically by hardware.
The
UARTxRTS
output can then still be manually controlled by the
MRTS
bit
in the
UARTx_MCR
register.
On reset, when the UART is not yet enabled and the port multi-
plexing has not been programmed, the
UARTxRTS
pin is not driven.
Some applications may require the
UARTxRTS
signal to be pulled to
either state by a resistor during reset.
Summary of Contents for EZ-KIT Lite ADSP-BF506F
Page 50: ...Contents l ADSP BF50x Blackfin Processor Hardware Reference ...
Page 92: ...Development Tools 1 30 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 110: ...Interface Overview 3 12 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 236: ...Internal Flash Memory Control Registers 6 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 650: ...Programming Examples 15 56 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 804: ...Programming Examples 17 92 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1194: ...Programming Examples 24 90 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1256: ...ACM Registers A 50 ADSP BF50x Blackfin Processor Hardware Reference ...
Page 1264: ...Boundary Scan Architecture B 8 ADSP BF50x Blackfin Processor Hardware Reference ...