Philips LPC2119 User Manual page 130

Philips Semiconductors
ARM-based Microcontroller
UART1 Modem Control Register (U1MCR - 0xE0010010)
The U1MCR enables the modem loopback mode and controls the modem output signals.
Table 97: UART1 Modem Control Register Bit Descriptions (U1MCR - 0xE0010010)
U1MCR Function
0 DTR Control
1 RTS Control
2 Reserved
3 Reserved
Loopback
4
Mode Select
7:5 Reserved
UART1
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.
Reserved, user software should not write ones to reserved bits. The value read from a
reserved bit is not defined.
0: Disable modem loopback mode
1: Enable modem loopback mode
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.
Reserved, user software should not write ones to reserved bits. The value read from a
reserved bit is not defined.
LPC2119/2129/2292/2294
Description
130
Preliminary User Manual
Reset
Value
0
0
NA
NA
0
NA
January 08, 2004