UART Modules
MCF52211 ColdFire® Integrated Microcontroller Reference Manual, Rev. 2
24-12 Freescale Semiconductor

24.3.7 UART Transmit Buffers (UTBn)

The transmit buffers consist of the transmitter holding register and the transmitter shift register. The
holding register accepts characters from the bus master if UART’s USRn[TXRDY] is set. A write to the
transmit buffer clears USRn[TXRDY], inhibiting any more characters until the shift register can accept
more data. When the shift register is empty, it checks if the holding register has a valid character to be sent
(TXRDY = 0). If there is a valid character , the shift register loads it and sets USRn[TXRDY] again. Writes
to the transmit buffer when the UART’s TXRDY is cleared and the transmitter is disabled have no effect
on the transmit buffer.
Figure 24-9 shows UTBn. TB contains the character in the transmit buffer.

24.3.8 UART Input Port Change Registers (UIPCRn)

The UIPCRs, shown in Figure 24-10, hold the current state and the change-of-state for UCTSn.
IPSBAR
Offset:
0x00_020C (URB0)
0x00_024C (URB1)
0x00_028C (URB2)
Access: User read-only
76543210
RRB
W
Reset:11111111
Figure 24-8. UART Receive Buffer (URBn)
IPSBAR
Offset:
0x00_020C (UTB0)
0x00_024C (UTB1)
0x00_028C (UTB2)
Access: User write-only
76543210
R
WTB
Reset:00000000
Figure 24-9. UART Transmit Buffer (UTBn)
IPSBAR
Offset:
0x00_0210 (UIPCR0)
0x00_0250 (UIPCR1)
0x00_0290 (UIPCR2)
Access: User read-only
76543210
R 0 0 0 COS 1 1 1 CTS
W
Reset:0000111UCTSn
Figure 24-10. UART Input Port Changed Registers (UIPCRn)