HD6432621 Hitachi, HD6432621 Datasheet - Page 771

• Manufacturer Part Number: HD6432621
• Description: (HD64F262x Series) 16-Bit Microcomputer
• Manufacturer: Hitachi

21B.11 Direct Transitions
21B.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.
(1) 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.
(2) 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.
21B.12 ø Clock Output Disabling Function
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 21B-6 shows the state of the ø pin in each processing state.
Table 21B-6 ø Pin State in Each Processing State
DDR
PSTOP
Hardware standby mode
Software standby mode, watch
mode, and direct transition
Sleep mode and subsleep mode
High-speed mode, medium-speed
mode, and subactive mode
0
—
High impedance
High impedance
High impedance
High impedance
1
0
High impedance
Fixed high
ø output
ø output
1
1
High impedance
Fixed high
Fixed high
Fixed high
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