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UART Modules
MCF5213 ColdFire® Integrated Microcontroller Reference Manual, Rev. 3
Freescale Semiconductor
21-13
21.3.9
UART Auxiliary Control Register (UACR
n
)
21.3.10 UART Interrupt Status/Mask Registers (UISR
n
/UIMR
n
)
, provide status for all potential interrupt sources. UISR
n
contents are
masked by UIMR
n
. If corresponding UISR
n
and UIMR
n
bits are set, internal interrupt output is asserted.
If a UIMR
n
bit is cleared, state of the corresponding UISR
n
bit has no effect on the output.
The UISR
n
and UIMR
n
registers share the same space in memory. Reading this register provides the user
with interrupt status, while writing controls the mask bits.
Table 21-8. UIPCR
n
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 UIPCR
n
. Reading UIPCR
n
clears UISR
n
[COS].
1 A change-of-state longer than 25–50
μ
s occurred on the U
n
CTS input. UACR
n
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 U
n
CTS. If
U
n
CTS is detected asserted at that time, COS is set, which initiates an interrupt if UACR
n
[IEC] is enabled.
0 The current state of the U
n
CTS input is asserted.
1 The current state of the U
n
CTS input is deasserted.
IPSBAR
Offset:
0x00_0210 (UACR0)
0x00_0250 (UACR1)
0x00_0290 (UACR2)
Access: User write-only
7
6
5
4
3
2
1
0
R
W
0
0
0
0
0
0
0
IEC
Reset:
0
0
0
0
0
0
0
0
Figure 21-11. UART Auxiliary Control Registers (UACR
n
)
Table 21-9. UACR
n
Field Descriptions
Field
Description
7–1
Reserved, must be cleared.
0
IEC
Input enable control.
0 Setting the corresponding UIPCR
n
bit has no effect on UISR
n
[COS].
1 UISR
n
[COS] is set and an interrupt is generated when the UIPCR
n
[COS] is set by an external transition on the
U
n
CTS input (if UIMR
n
[COS] equals 1).