Cypress FM4 Series - Page 441

CHAPTER 9: External Interrupt and NMI Control Sections
FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E 441
Canceling an External Interrupt Request
When the external interrupt detection condition is set to the H or L level, an interrupt factor is held in the
External Interrupt Factor Register (EIRR) even if an external interrupt request input (INTxx) is canceled.
Therefore, an external interrupt request (INTIRQxx) remains output to the interrupt controller.
Execute the following steps to cancel an external interrupt request.
1. Read the External Interrupt Factor Register (EIRR), and check the interrupt factor.
2. Write "0" to the corresponding bit in the External Interrupt Factor Clear Register (EICL) to clear it.
3. Read the External Interrupt Factor Register (EIRR), and check that the interrupt factor is cleared.
Figure 3-2 Clearing an Interrupt Factor
"H"
Outputs an interrupt request.
INTIRQxx
Inputs an interrupt request.
INTxx
When "H" level detection is specified
Canceled when "0" is written to EICL.
Figure 3-3 Canceling an External Interrupt Request
Checks an interrupt cause.
(EIRR)
Clears an interrupt cause.
(EICL)
Checks that an interrupt is
cleared. (EIRR)
Starts clearing.
Completes clearing.
Checks an interrupt factor.
(EIRR)
Clears an interrupt factor.
(EICL)