R01UH0822EJ0100 Rev.1.00
Page 179 of 1041
Jul 31, 2019
RX13T Group
11. Low Power Consumption
11.6
Low Power Consumption Modes
11.6.1
Sleep Mode
11.6.1.1
Entry to Sleep Mode
When the WAIT instruction is executed while the SBYCR.SSBY bit is 0, the CPU enters sleep mode. In sleep mode, the
CPU stops operating but the contents of its internal registers are retained. Other peripheral functions do not stop.
Counting by the IWDT stops if a transition to sleep mode is made while the IWDT is being used in auto-start mode and
the OFS0.IWDTSLCSTP bit is 1. In the same way, counting by the IWDT stops if a transition to sleep mode is made
while the IWDT is being used in register start mode and the IWDTCSTPR.SLCSTP bit is 1.
Furthermore, counting by the IWDT continues if a transition to sleep mode is made while the IWDT is being used in
auto-start mode and the OFS0.IWDTSLCSTP bit is 0 (counting by the IWDT continues through transitions to low power
consumption modes). In the same way, counting by the IWDT continues if a transition to sleep mode is made while the
IWDT is being used in register start mode and the IWDTCSTPR.SLCSTP bit is 0.
To use sleep mode, make the following settings and then execute a WAIT instruction.
(1) Set the PSW.I bit
of the CPU to 0.
(2) Set the interrupt request destination
to be used for exit from sleep mode.
(3) Set the priority
of the interrupt to be used for exit from sleep mode to a level higher than the setting of the
PSW.IPL[3:0] bits
of the CPU.
(4) Set the IERm.IENj bit
to 1 for the interrupt.
(5) Read the I/O register that is written last and confirm that the written value has been reflected.
(6) Execute the WAIT instruction (this automatically sets the I bit
in the PSW of the CPU to 1).
Note 1. For details, refer to section 2, CPU.
Note 2. For details, refer to section 14.4.3, Selecting Interrupt Request Destinations.
Note 3. For details, refer to section 14, Interrupt Controller (ICUb).