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Registers
1524
SPRUH82C – April 2013 – Revised September 2016
Copyright © 2013–2016, Texas Instruments Incorporated
Universal Asynchronous Receiver/Transmitter (UART)
31.3.7 Modem Control Register (MCR)
The modem control register (MCR) is shown in
and described in
. The modem
control register provides the ability to enable/disable the autoflow functions, and enable/disable the
loopback function for diagnostic purposes.
(1)
All UARTs do not support this feature, see your device-specific data manual for supported features. If this feature is not available, this bit
is reserved and should be cleared to 0.
Figure 31-15. Modem Control Register (MCR)
31
16
Reserved
R-0
15
6
5
4
3
2
1
0
Reserved
AFE
(1)
LOOP
OUT2
OUT1
RTS
(1)
Rsvd
R-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R-0
LEGEND: R/W = Read/Write; R = Read only; -
n
= value after reset
Table 31-16. Modem Control Register (MCR) Field Descriptions
Bit
Field
Value
Description
31-6
Reserved
0
Reserved
5
AFE
Autoflow control enable. Autoflow control allows the UARTn_RTS and UARTn_CTS signals to provide
handshaking between UARTs during data transfer. When AFE = 1, the RTS bit determines the autoflow
control enabled. Note that all UARTs do not support this feature, see your device-specific data manual
for supported features. If this feature is not available, this bit is reserved and should be cleared to 0.
0
Autoflow control is disabled.
1
Autoflow control is enabled:
• When RTS = 0, UARTn_CTS is only enabled.
• When RTS = 1, UARTn_RTS and UARTn_CTS are enabled.
4
LOOP
Loop back mode enable. LOOP is used for the diagnostic testing using the loop back feature.
0
Loop back mode is disabled.
1
Loop back mode is enabled. When LOOP is set, the following occur:
• The UARTn_TXD signal is set high.
• The UARTn_RXD pin is disconnected
• The output of the transmitter shift register (TSR) is lopped back in to the receiver shift register (RSR)
input.
3
OUT2
0
OUT2 Control Bit
2
OUT1
0
OUT1 Control Bit
1
RTS
RTS control. When AFE = 1, the RTS bit determines the autoflow control enabled. Note that all UARTs
do not support this feature, see your device-specific data manual for supported features. If this feature
is not available, this bit is reserved and should be cleared to 0.
0
UARTn_RTS is disabled, UARTn_CTS is only enabled.
1
UARTn_RTS and UARTn_CTS are enabled.
0
Reserved
0
Reserved