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UART2
LH75400/01/10/11 (Preliminary) User’s Guide
20-34
6/17/03
20.3.2.23 Internal Mode Register
Register Bank: 2
IMD is the Internal Mode Register. The IMD Register defines the General Device Operat-
ing Mode.
Table 20-55. IMD Register
BIT
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
FIELD
///
RESET
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
RW
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
BIT
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
FIELD
///
///
FRD
µ
LM
LEM
RESET
0
0
0
0
0
0
0
0
0
0
0
0
1
1
0
0
RW
R
R
R
R
R
R
R
R
R
R
R
R
RW
RW
RW
RW
ADDR
0xFF 0x10
Table 20-56. IMD Register Definitions
BITS NAME
DESCRIPTION
31:4
///
Reserved
Do not modify. Read as zero.
3
///
Reserved
Do not modify. Read as one.
2
RFD
Receive FIFO Depth
Configures the depth of the Rx FIFO.
0 = Four bytes
1 = One byte. The FIFO acts as a 1-byte buffer to emulate the 8250A UART.
1
LM
LAN Mode
Enables the UART to recognize and/or match an address using
the 9-bit MCS-51 asynchronous protocol.
0 = Normal Mode
1 =
µ
LAN Mode
See the ACTRL0 Register for a complete description of the
µ
LAN Mode.
0
LEM
Loopback/Echo Mode Select
Selects either loopback or echo operation,
depending on the operating mode selected by bit [4] of the MCTRL Register.
In Loopback Mode (LC = 1), this bit selects between local and remote loopback:
0 = Local loopback
1 = Remote loopback
In Echo Mode (LC = 0), this bit selects between echo or non-echo operation:
0 = No echo
1 = Echo operation