UART Registers
15-32
ADSP-BF50x Blackfin Processor Hardware Reference
The receive FIFO interrupt threshold (
RFIT
) bit controls the timing of the
RFCS
status bit. If
RFIT
=0, the receive threshold is two. If
RFIT
=1, the
threshold is four words in the receive buffer.
The manual request to send (
MRTS
) bit controls the state of the
UARTxRTS
output pin only if
ARTS
=0. A value of
MRTS
=0 forces the
UARTxRTS
pin to its
deassertive state, signaling to the external device that the UART is not
ready to receive. A value of
MRTS
=1 forces the
UARTxRTS
pin to its assertive
state, signaling to the external device that the UART is ready to receive.
The automatic RTS (
ARTS
) bit enables the receive buffer to control the
RTS output depending on the threshold programmed by the
RFTR
bit. If
RFRT
=0, the
RTS
signal is deasserted when already two words are held by
the receive buffer and a third start bit is detected. It is re-asserted if the
buffer contains less than two words. If
RFRT
=1, the
RTS
signal is deasserted
when already four words are held by the receive buffer and a fifth start bit
is detected. The
RTS
signal is re-asserted if the buffer contains less than
four words.
Similarly, the automatic CTS (
ACTS
) bit must be set to enable the
CTS
input pin for UARTxTX handshaking. If enabled, the
CTS
status bit in the
UARTx_MSR
register holds the value (if
FCPOL
=
1
) or complement value (if
FCPOL
=0) of the
CTS
input pin. The
CTS
status bit can be used to determine
if the external device is ready to receive data (
CTS
=1) or if it is busy
(
CTS
=0). If
ACTS
=0, the UARTxTX handshaking protocol is disabled, and
the UARTxTX line transmits data whenever there is data to send, regard-
less of the value of
CTS
. The transmitter off (
XOFF
) bit can be used to pause
an on-going transmission by software when
ACTS
=0. Similarly to auto-
matic CTS mode, the
XOFF
bit prevents the data in the
UARTx_THR
register
Table 15-6. UART Modem Control Register Memory-Mapped Addresses
Register Name
Memory-Mapped Address
UART0_MCR
0xFFC0 0410
UART1_MCR
0xFFC0 2010
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 ...