Microcontroller User's Manual

MOTOROLA Chapter 23. UART Modules 23-9
Register Descriptions
23.3.5 UART Command Registers (UCRn)
The UCRs, shown in Figure 23-6, supply commands to the UART. Only multiple
commands that do not conflict can be specified in a single write to a UCRn. For example,
RESET TRANSMITTER and ENABLE TRANSMITTER cannot be specified in one command.
Table 23-6 describes UCRn fields and commands. Examples in Section 23.5.2,
“Transmitter and Receiver Operating Modes,” show how these commands are used.
Table 23-5. UCSRn Field Descriptions
Bits Name Description
7–4 RCS Receiver clock select. Selects the clock source for the receiver channel.
1101 Prescaled system clock
1110 DTIN divided by 16
1111 DTIN
3–0 TCS Transmitter clock select. Selects the clock source for the transmitter channel.
1101 Prescaled system clock
1110 DTIN divided by 16
1111 DTIN
76 43210
Field — MISC TC RC
Reset 0000_0000
R/W Write only
Address IPSBAR + 0x208(UCR0), 0x248(UCR1), 0x288(UCR2)
Figure 23-6. UART Command Register (UCRn)