UART/Autobaud Control and Status Registers
12-35
UART Devices
The mode of operation can be programmed by writing to MDR1[2:0]; therefore
the MDR1 must be programmed on start-up after configuration of the configu-
ration registers (DLL, DLH, LCR). The value of MDR1[2:0] must not be
changed again during normal operation.
Table 12–38. Mode Definition Register 1 (MDR1)
Bit
Name
Value
Function
R/W
Reset
Value
7–3
–
Reserved
R/W
00000
2–0
MODE_SELECT
†
000: UART
R/W
111
010
UART with autobauding
111
Disables UART/default state
All the other values are reserved.
† The MODE_SELECT = 0x7 setting disables the UART module by disabling the FIFO and the state machine. It does not gate
the functional clock to the module. The lowest power state is not achieved by setting MODE_SELECT = 0x7, but by putting the
UART into sleep mode. The lowest power state is achieved when in sleep mode witht DLL = 0xFFFF and DLH = 0xFFFF.
The UART autobauding status register (UASR) returns the speed, the number
of bits by characters, and the type of the parity in UART autobaud mode.
Table 12–39. Autobauding Status Register (UASR)
Bit
Name
Value
Function
R/W
Reset
Value
7–6
PARITY_TYPE
00
00: No parity identified
R
00
01
Parity space
10
Even parity
11
Odd parity
5
BIT_BY_CHAR
0
7-bit character identified
R
0
1
8-bit character identified
Note:
This register is used to set up transmission according to characteristics of previous reception instead of LCR, DLL, and
DLH registers when UART is in autobaud mode.To reset the autobauding hardware (to start a new AT detection) or to
set the UART in standard mode (no autobaud), MDR1[2:0] must be set to reset state 111 then to the UART in autobaud
mode 010 or UART in standard mode 000.