HD6417751RBP240V Datasheet, PDF (350/1226 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

9. Power-Down Modes
Table 9.4 State of Registers in Standby Mode
Module
Initialized Registers
Registers That Retain
Their Contents
Interrupt controller
—
All registers
User break controller
—
All registers
Bus state controller
—
All registers
On-chip oscillation circuits
—
All registers
Timer unit
TSTR register*
All registers except TSTR
Realtime clock
—
All registers
Direct memory access controller —
All registers
Serial communication interface
See Appendix A, Address List See Appendix A, Address List
Notes: DMA transfer should be terminated before making a transition to standby mode. Transfer
results are not guaranteed if standby mode is entered during transfer.
* Not initialized when the realtime clock (RTC) is in use (see section 12, Timer Unit
(TMU)).
The procedure for a transition to standby mode is shown below.
1. Clear the TME bit in the WDT timer control register (WTCSR) to 0, and stop the WDT.
Set the initial value for the up-count in the WDT timer counter (WTCNT), and set the clock to
be used for the up-count in bits CKS2–CKS0 in the WTCSR register.
2. Set the STBY bit in the STBCR register to 1, then execute a SLEEP instruction.
3. When standby mode is entered and the chip's internal clock stops, a low-level signal is output
at the STATUS1 pin, and a high-level signal at the STATUS0 pin.
9.6.2 Exit from Standby Mode
Standby mode is exited by means of an interrupt (NMI, IRL, or on-chip peripheral module) or a
reset via the RESET and MRESET pins.
Exit by Interrupt: A hot start can be performed by means of the on-chip WDT. When an NMI,
IRL*¹, RTC, or GPIO*² interrupt is detected, the WDT starts counting. After the count overflows,
clocks are supplied to the entire chip, standby mode is exited, and the STATUS1 and STATUS0
pins both go low. Interrupt exception handling is then executed, and the code corresponding to the
interrupt source is set in the INTEVT register. In standby mode, interrupts are accepted even if the
BL bit in the SR register is 1, and so, if necessary, SPC and SSR should be saved to the stack
before executing the SLEEP instruction.
Rev.4.00 Oct. 10, 2008 Page 250 of 1122
REJ09B0370-0400