Motorola MCF5281 用户手册
23-6
MCF5282 User’s Manual
MOTOROLA
Register Descriptions
23.3.2 UART Mode Register 2 (UMR2n)
The UMR2n registers control UART module configuration. UMR2n can be read or written
when the mode register pointer points to it, which occurs after any access to UMR1n.
UMR2n accesses do not update the pointer.
when the mode register pointer points to it, which occurs after any access to UMR1n.
UMR2n accesses do not update the pointer.
Table 23-3 describes UMR2n fields.
7
6
5
4
3
0
Field
CM
TxRTS
TxCTS
SB
Reset
0000_0000
R/W
R/W
Address IPSBAR + 0x200 (UART0), 0x240 (UART1), 0x280 (UART2). After UMR1n is read or written, the pointer points to
UMR2n.
Figure 23-3. UART Mode Register 2 (UMR2n)
Table 23-3. UMR2n Field Descriptions
Bits
Name
Description
7–6
CM
Channel mode. Selects a channel mode. Section 23.5.3, “Looping Modes,” describes individual modes.
00 Normal
01 Automatic echo
10 Local loop-back
11 Remote loop-back
00 Normal
01 Automatic echo
10 Local loop-back
11 Remote loop-back
5
TxRTS Transmitter ready-to-send. Controls negation of RTS to automatically terminate a message transmission.
Attempting to program a receiver and transmitter in the same channel for RTS control is not permitted and disables
RTS control for both.
0 The transmitter has no effect on RTS.
1 In applications where the transmitter is disabled after transmission completes, setting this bit automatically
RTS control for both.
0 The transmitter has no effect on RTS.
1 In applications where the transmitter is disabled after transmission completes, setting this bit automatically
clears UOP[RTS] one bit time after any characters in the channel transmitter shift and holding registers are
completely sent, including the programmed number of stop bits.
completely sent, including the programmed number of stop bits.
4
TxCTS Transmitter clear-to-send. If both TxCTS and TxRTS are enabled, TxCTS controls the operation of the transmitter.
0 CTS has no effect on the transmitter.
1 Enables clear-to-send operation. The transmitter checks the state of CTS each time it is ready to send a character.
1 Enables clear-to-send operation. The transmitter checks the state of CTS each time it is ready to send a character.
If CTS is asserted, the character is sent; if it is negated, the channel TXD remains in the high state and
transmission is delayed until CTS is asserted. Changes in CTS as a character is being sent do not affect its
transmission.
transmission is delayed until CTS is asserted. Changes in CTS as a character is being sent do not affect its
transmission.