HD6432646 Hitachi, HD6432646 Datasheet - Page 784

• Manufacturer Part Number: HD6432646
• Description: (HD64F264x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

22.11
22.11.1 Overview of Direct Transitions
There are three modes, high-speed, medium-speed, and sub-active, in which the CPU executes
programs. When a direct transition is made, there is no interruption of program execution when
shifting between high-speed and sub-active modes. Direct transitions are enabled by setting the
LPWRCR DTON bit to 1, then executing the SLEEP instruction. After a transition, direct
transition interrupt exception processing starts.
Direct Transitions from High-Speed Mode to Sub-Active Mode: Execute the SLEEP
instruction in high-speed mode when the SBYCR SSBY bit = 1, LPWRCR LSON bit = 1, and
DTON bit = 1, and TSCR (WDT1) PSS bit = 1 to make a transition to sub-active mode.
Direct Transitions from Sub-Active Mode to High-Speed Mode: Execute the SLEEP
instruction in sub-active mode when the SBYCR SSBY bit = 1, LPWRCR LSON bit = 0, and
DTON bit = 1, and TSCR (WDT1) PSS bit = 1 to make a direct transition to high-speed mode
after the time set in SBYCR STS2 to STS0 has elapsed.
22.12
Output of the ø clock can be controlled by means of the PSTOP bit in SCKCR, and DDR for the
corresponding port. When the PSTOP bit is set to 1, the ø clock stops at the end of the bus cycle,
and ø output goes high. ø clock output is enabled when the PSTOP bit is cleared to 0. When DDR
for the corresponding port is cleared to 0, ø clock output is disabled and input port mode is set.
Table 22-6 shows the state of the ø pin in each processing state.
Table 22-6 ø Pin State in Each Processing State
DDR
PSTOP
Hardware standby mode
Software standby mode, watch
mode, and direct transition
Sleep mode and sub-sleep mode
High-speed mode, medium-speed
mode
Sub-active mode
750
Direct Transitions
ø Clock Output Disabling Function
0
—
High impedance
High impedance
High impedance
High impedance
High impedance
1
0
High impedance
Fixed high
ø output
ø output
ø
SUB
output
1
1
High impedance
Fixed high
Fixed high
Fixed high
Fixed high