Cypress FM4 Series - Operations of External Interrupt Control Section

CHAPTER 9: External Interrupt and NMI Control Sections
440 FM4 Peripheral Manual, Doc. No. 002-04856 Rev. *E
3.1 Operations of External Interrupt Control Section
This section shows the operations of the external interrupt control section.
Overview of Operations in External Interrupt Control Section
The external interrupt control section outputs an external interrupt request to the interrupt controller in the
following procedure.
1. The signal input to pin INTxx detects the edge or level specified in the External Interrupt Level Register
(ELVR). The edge or level to be detected can be selected from the following four types:
H level, L level, rising edge, falling edge
2. The detected interrupt input is held in the interrupt factor F/F.
It is read with the External Interrupt Factor Register (EIRR).
The held interrupt factor is cleared with the External Interrupt Factor Clear Register (EICL).
3. If an external interrupt is enabled with the External Interrupt Enable Register (ENIR), an external
interrupt request (INTIRQxx) is output to the interrupt controller.
Setting Procedure
Execute the following steps to configure external interrupt setting.
1. Disable an external interrupt with the External Interrupt Enable Register (ENIR).
2. Specify the detection condition (effective edge or level) with the External Interrupt Factor Level Register
(ELVR).
3. Read the External Interrupt Factor Level Register (ELVR).
4. Clear the external interrupt factor with the External Interrupt Factor Clear Register (EICL).
5. Enable the external interrupt with the External Interrupt Enable Register (ENIR).
Figure 3-1 External Interrupt Setting Procedure
Disables an external interrupt.
(ENIR)
Specifies the detection condition.
(ELVR)
Checks the detection condition.
(ELVR)
Clears an interrupt factor.
(EICL)
Enables ans external interrupt.
(ENIR)
Starts setting.
Completes setting.