MC68HC901 Datasheet, PDF (46/73 Pages) Motorola, Inc – Multi-Function Peripheral

Universal Synchronous/Asynchronous Receiver-Transmitter
7.1.3 USART Control Register (UCR)
This register selects the clock mode and the character format for the receive and transmit
sections.
UCR REGISTER
BIT
7
6
5
4
3
2
1
0
FIELD
CLK
CL1
CL0
ST1
ST0
PE
E/O
0
RESET
0
0
0
0
0
0
0
U
ADDR
$29
CLK — Clock Mode
1 = Data clocked into and out of receiver and transmitter at one sixteenth the frequency
of their respective clocks.
0 = Data clocked into and out of receiver and transmitter at the frequency of their
respective clocks.
CL1-CL0 — Character Length
These bits specify the length of the character exclusive of start bits and parity.
CL1
CL0
0
0
0
1
1
0
1
1
CHARACTER LENGTH
8 Bits
7 Bits
6 Bits
5 Bits
ST1-ST0 — Start/Stop Bit and Format Control
These bits select the number of start and stop bits and specify the character format.
ST1
ST0
START BITS
0
0
0
0
1
1
1
0
1
1
1
1
NOTE: Used with divide-by-16 mode only.
STOP BITS
0
1
1-1/2
2
FORMAT
Synchronous
Asynchronous
Asynchronous (See note)
Asynchronous
MOTOROLA
MC68HC901 USER’S MANUAL
7-3