
MOTOROLA
PROGRAMMING REFERENCE
MMC2001
C-42
REFERENCE MANUAL
WS — Word Size
This bit specifies a character length of eight or seven bits (not including start, stop, or
parity bits). When WS is set, the transmitter and receiver are in eight-bit mode. When
WS is cleared, they are in seven-bit mode. The transmitter then ignores B7, and the
receiver sets B7 to zero. This bit can be changed between transmissions or recep-
tions. If it is changed while a transmission or reception is in progress, however, the
length of the current character being transmitted or received is unpredictable.
0 =
7-bit transmit and receive character length
1 =
8-bit transmit and receive character length
At reset, this bit is cleared to zero.
C.9.5 UART BRG Register (UBRGR)
This register specifies the divide ratio of the prescaler in the UART bit clock genera-
tor.
Figure C-40 UART BRG Register
CD — Clock Divider
These bits determine the bit clock generator output rate. The CD field is used to pre-
set a 12-bit counter that is decremented at the system clock rate. The value 0x000
produces the maximum clock rate (equal to the system clock). The value 0xFFF
pro-
duces the minimum clock rate (divide by 4096).
C.9.6 UART Status Register (USR)
The read/write UART status register indicates the status of the RTS pin, input transi-
tions on the pin, and status of the transmit and receive FIFOs.
Figure C-41 UART Status Register
U0BRGR — UART0 BRG Register
10009084
U1BRGR — UART1 BRG Register
1000A084
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
0
0
0
0
CD
W
RESET:
0
0
0
0
0
0
0
0
0
0
0
0
U0SR — UART0 Status Register
10009086
U1SR — UART1 Status Register
1000A086
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
R
TX
MPTY
RTSS
TRDY
0
0
0
RRDY
0
0
0
RTSD
0
0
0
0
0
W
RESET:
1
0
1
0
0
Freescale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
nc.
..