MC96FR116C
November, 2018 Rev.1.8
59
the program address is retrieved from the stack by executing RETI instruction to restart from the
position where the interrupt is accepted. The following figure shows the sequence.
NOTE
Interrupt flags due to UART TX and FLASH are not auto-cleared when the CPU accepts the request.
10.6 Effective time of Interrupt Request
To activate interrupt request from interrupt sources, both EA bit in IE register and individual enable bit
INTnE in IEx register must be enabled. At this time, the effective time of interrupt request after setting
control registers is as follows.
Saves PC to stack to continue program
execution after serving ISR
IE.EA Flag
1
IEx.y
1
1
Saves Program Counter Low Byte
SP
SP + 1
M(SP)
(PCL)
2
Saves Program Counter High Byte
SP
SP + 1
M(SP)
(PCH)
EA=0
3
Produces Interrupt Vector Address
(Interrupt Vector Address)
4
Jumps to ISR(Interrupt Service Routine)
5
Return from ISR
RETI
6
EA = 1
Restores Program Counter High Byte
(PCH)
M(SP), SP
SP-1
7
Executes Main Program
9
Restores Program Counter Low Byte
(PCL)
M(SP), PC
SP-1
8
Figure 10-3 Sequence of Interrupt handling