h8s-2649 Renesas Electronics Corporation., h8s-2649 Datasheet - Page 618

• Manufacturer Part Number: h8s-2649
• Description: Renesas 16-bit Single-chip Microcomputer H8s Family/h8s/2600 Series
• Manufacturer: Renesas Electronics Corporation.

Section 21 Power-Down Modes
21.2
Medium-Speed Mode
When the SCK2 to SCK0 bits in SCKCR are set to 1 in high-speed mode, the operating mode
changes to medium-speed mode as soon as the current bus cycle ends. In medium-speed mode, the
CPU operates on the operating clock (φ/2, φ/4, φ/8, φ/16, or φ/32) specified by the SCK2 to SCK0
bits. The bus master (DTC) other than the CPU operates in medium-speed mode.
On-chip peripheral modules other than the bus masters always operate on the high-speed clock (φ).
In medium-speed mode, a bus access is executed in the specified number of states with respect to
the bus master operating clock. For example, if φ/4 is selected as the operating clock, on-chip
memory is accessed in four states, and internal I/O registers in eight states.
Medium-speed mode is canceled by clearing all of bits SCK2 to SCK0 to 0. A transition is made
to high-speed mode and medium-speed mode is canceled at the end of the current bus cycle.
If the SLEEP instruction is executed when the SSBY bit in SBYCR = 0 and LSON bit in
LPWRCR = 0, a transition is made to sleep mode. When sleep mode is canceled by an interrupt,
medium-speed mode is restored.
When the SLEEP instruction is executed with the SSBY bit = 1, LSON bit in LPWRCR = 0, and
PSS bit in TCSR (WDT1) = 0, operation shifts to software standby mode. When software standby
mode is canceled by an external interrupt, medium-speed mode is restored.
When the RES pin is driven low and medium-speed mode is cancelled, operation shifts to the reset
state. The same applies to a reset caused by an overflow of the watchdog timer.
When the STBY pin is driven low, a transition is made to hardware standby mode.
Figure 21.2 shows the timing for transition to and clearance of medium-speed mode.
Rev. 2.00 Dec. 05, 2005 Page 580 of 724
REJ09B0200-0200