Uart1 Modem Control Register (U1Mcr - 0Xe001 0010); User Manual - Philips LPC2101 User Manual

Philips Semiconductors
Volume 1
Table 109: UART1 Line Control Register (U1LCR - address 0xE001 000C) bit description
Bit Symbol
6 Break Control
7 Divisor Latch
Access Bit (DLAB)

10.3.10 UART1 Modem Control Register (U1MCR - 0xE001 0010)

The U1MCR enables the modem loopback mode and controls the modem output signals.
Table 110: UART1 Modem Control Register (U1MCR - address 0xE001 0010) bit description
Bit Symbol
0 DTR Control
1 RTS Control
3:2 -
4 Loopback Mode
Select
5:3 -
6 RTSen
7 CTSen
Auto-flow control
If auto-RTS mode is enabled the UART1's receiver FIFO hardware controls the RTS1
output of the UART1. If the auto-CTS mode is enabled the UART1's U1TSR hardware will
only start transmitting if the CTS1 input signal is asserted.
Auto-RTS

User manual

Value Description
0 Disable break transmission.
1 Enable break transmission. Output pin UART1 TXD is forced to
logic 0 when U1LCR[6] is active HIGH.
0 Disable access to Divisor Latches.
1 Enable access to Divisor Latches.
Value Description
Source for modem output pin, DTR. This bit reads as 0 when
modem loopback mode is active.
Source for modem output pin RTS. This bit reads as 0 when
modem loopback mode is active.
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
The modem loopback mode provides a mechanism to perform
diagnostic loopback testing. Serial data from the transmitter is
connected internally to serial input of the receiver. Input pin,
RXD1, has no effect on loopback and output pin, TXD1 is held
in marking state. The four modem inputs (CTS, DSR, RI and
DCD) are disconnected externally. Externally, the modem
outputs (RTS, DTR) are set inactive. Internally, the four modem
outputs are connected to the four modem inputs. As a result of
these connections, the upper four bits of the U1MSR will be
driven by the lower four bits of the U1MCR rather than the four
modem inputs in normal mode. This permits modem status
interrupts to be generated in loopback mode by writing the
lower four bits of U1MCR.
0 Disable modem loopback mode.
1 Enable modem loopback mode.
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
Auto-RTS control bit.
0 Disable auto-RTS flow control.
1 Enable auto-RTS flow control.
Auto-CTS control bit.
0 Disable auto-CTS flow control.
1 Enable auto-CTS flow control.
Rev. 01 — 12 January 2006
UM10161
Chapter 10: UART1
Reset value
0
0
Reset value
0
0
NA
0
NA
0
0
© Koninklijke Philips Electronics N.V. 2006. All rights reserved.
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