RX610 Group
10. ICU
R01UH0032EJ0120 Rev.1.20
Page 249 of 1006
Feb 20, 2013
10.4.6
External Interrupts
External interrupts are interrupts that have the signals on the IRQn pins (n = 0 to 15) as sources. Figure 10.8 is a block
diagram of the circuit for an external interrupt.
RQMD
IRQ15
Rising-edge
detection
Falling-edge
detection
Both-edge
detection
Request
R
RQEN
Low-level
detection
IRQ0
Destination
(CPU/DTC/DMAC)
EN
Clearing signal
Input buffer
Pm.ICR
Figure 10.8 Block Diagram of External Interrupts
For external interrupts, level detection (low level) or edge detection (falling edge, rising edge, or both edges) is selected
by the IRQMD[1:0] bits in IRQCRn.
To set the IRQMD[1:0] bits in IRQCRn, follow the procedure below.
1.
Use the IRQEN bit in IRQERn and the IENj bit in IERi to disable detection and requesting of the external interrupt.
2.
Set the IRQMD[1:0] bits in IRQCRn.
3.
Clear the IR flag in IRi.
4.
Use the IRQEN bit in IRQERn and IENj bit in IERi to enable detection and requesting of the external interrupt.
For details on operation in the cases of edge- and level-detected external interrupts, see section 10.4.2, Interrupt Status
Flag.
When an external interrupt is in use, the input buffer of the IRQn pin should be enabled by the corresponding Bj bit in
Pm.ICR.
When modifying the value of the Bj bit in Pm.ICR, follow the procedure below.
1.
Use the IRQEN bit in IRQERn and the IENj bit in IERi to disable detection and requesting of the external interrupt.
2.
Modify the setting of the Bj bit in Pm.ICR.
3.
Clear the IR flag in IRi after four cycles of the PCLK clock.
4.
Use the IRQEN bit in IRQERn and the IENj bit in IERi to enable detection and requesting of the external interrupt.
For the correspondence between the IRQn pins and the Bj bits in Pm.ICR, see section 14, I/O Ports.
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