Cypress FM4 Series - EWKUP Register

CHAPTER 7-3: VBAT Domain(B)
342 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
7.5 EWKUP Register
EWKUP Register displays and clears the request state of the wakeup.
bit
7
6
5
4
3
2
1
0
Field
Reserved
WUP0
Attribute
-
R/W
Initial value
-
0
The interface circuit type for this register is type 4.
[bit7:1] Reserved: Reserved bits
These bits read 0b0000000.
In a write access to these bits, write 0b0000000 to them.
[bit0] WUP0: Wakeup request bit
bit
Description
Reading
0
The VBAT Domain has accepted no wakeup request.
1
The VBAT Domain has accepted a wakeup request.
Writing
0
The VBAT Domain clears a wakeup request.
1
Writing 1 to this bit has no effect on operation.
The wakeup request function is enabled if Port function of P49/VWAKEUP pin set bit (VPFR1) in VBPFR
register is set to 1.
With the wakeup request function enabled, if the VBAT Domains detects a rising edge of the
P49/VWAKEUP pin, it accepts a wakeup request and makes an RTC interrupt to the interrupt control
circuit.
The wakeup request can be accepted at the 7th PCLK cycle from the wakeup request clear or later. To
clear a register in VBAT Domain, 7 PCLK cycles are required. So, if the standby mode or external reset is
entered before 7 PCLK cycles have elapsed, the wakeup request is not accepted because PCLK is
stopped.