UART Modules
MCF52211 ColdFire® Integrated Microcontroller Reference Manual, Rev. 2
Freescale Semiconductor 24-13

24.3.9 UART Auxiliary Control Register (UACRn)

The UACRs control the input enable.

24.3.10 UART Interrupt Status/Mask Registers (UISRn/UIMRn)

The UISRs, shown in Figure 24-12, provide status for all potential interrupt sources. UISRn contents are

masked by UIMRn. If corresponding UISRn and UIMRn bits are set, internal interrupt output is asserted.

If a UIMRn bit is cleared, state of the corresponding UISRn bit has no effect on the output.

The UISRn and UIMRn registers share th e same space in memory. Reading this register provides the user

with interrupt status, while writing controls the mask bits.

Table 24-8. UIPCRn Field Descriptions

Field Description
7–5 Reserved
4
COS
Change of state (high-to-low or low-to-high transition).
0 No change-of-state since the CPU last read UIPCRn. Reading UIPCRn clears UISRn[COS].
1 A change-of-state longer than 25–50 μs occurred on the UCTSn input. UACRn can be programmed to generate
an interrupt to the CPU when a change of state is detected.
3–1 Reserved
0
CTS
Current state of clear-to-send. Starting two serial clock periods after reset, CTS reflects the state of UCTSn. If
UCTSn is detected asserted at that time, COS is set, which initiates an interrupt if UACRn[IEC] is enabled.
0 The current state of the UCTSn input is asserted.
1 The current state of the UCTSn input is deasserted.
IPSBAR
Offset:
0x00_0210 (UACR0)
0x00_0250 (UACR1)
0x00_0290 (UACR2)
Access: User write-only
76543210
R
W0000000IEC
Reset:00000000

Figure 24-11. UART Auxiliary Control Registers (UACRn)

Table 24-9. UACRn Field Descriptions

Field Description
7–1 Reserved, must be cleared.
0
IEC
Input enable control.
0 Setting the corresponding UIPCRn bit has no effect on UISRn[COS].
1UISRn[COS] is set and an interrupt is generated when the UIPCRn[COS] is set by an external transition on the
UCTSn input (if UIMRn[COS] = 1).