RX610 Group
10. ICU
R01UH0032EJ0120 Rev.1.20
Page 252 of 1006
Feb 20, 2013
10.6.2
Returning from Software Standby Mode
The interrupt control unit can return operation from software standby mode in response to the NMI or an external
interrupt on the IRQn pins (n = 0 to 15).
When the NMI or an IRQn (n = 0 to 15) external interrupt is generated, the clock starts oscillating and the clock signal is
supplied throughout the LSI, and interrupt processing starts.
For the NMI to act as the trigger for return from software standby mode, the NMIEN bit in NMIER must be set to 1
(enabling the NMI).
For an IRQn (n = 0 to 15) external interrupt to act as the trigger for return from software standby mode, the following
conditions apply.
1.
The SSIj (j = 0 to 15) bit in SSIER enables the source as a trigger for return.
2.
The IRQEN bit in IRQERn enables the detection of external interrupts on the given IRQn pin.
3.
The IENj bit in IERi enables the given IRQn pin interrupt request.
4.
The ISEL[1:0] bits in ISELRi specify the CPU as the destination of the interrupt request.
5.
The IPR[2:0] bits in IPRi specify a priority level higher than that set by the IPL[2:0] bits in the PSW of the CPU.*
Note: * An interrupt source which has been specified as the fast interrupt is the highest-priority interrupt (other than the
NMI) regardless of the setting of the IPR[2:0] bits in IPR
i
. However, if the interrupt source specified as the fast
interrupt is to be used as a trigger for return from software standby mode, the setting of the IPR[2:0] bits in IPR
i
for that interrupt source must satisfy the above relevant condition above.
To cancel software standby mode by an interrupt IRQ0 to IRQ15 for which edge detection is set, 0 should be written to
the status flag (the IR bit in IRi of the ICU) of the corresponding interrupt at the beginning of the exception handling
routine for the interrupt.
In addition, when an interrupt IRQ0 to IRQ15 is not set as a trigger for return from software standby mode, the input
buffer of the corresponding pin becomes invalid in software standby mode and thus the input signal to the LSI is fixed
high. In such a case, the interrupt status flag (ICU.IRi.IR) might be set to 1 depending on the state of the pin. Therefore,
be sure to execute the WAIT instruction after an interrupt IRQ0 to IRQ15 that is not set as a trigger for cancelation
source is masked by the IERi.IENj bit, or its interrupt priority level is made lower by the IPRi.IPR bit. Moreover, clear
the interrupt status flag after returning from software standby mode.
For details on the low power consumption states, see section 8, Low Power Consumption.
Summary of Contents for RX600 Series
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