HD64336900G Datasheet, PDF (99/408 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcomputer H8 Family/H8/300H Tiny Series

Initial
Bit
Bit Name Value R/W Description
1
OSCHLT 1
R
External Clock Halt Detection Flag
• When OSCBAKE = 1
This bit indicates the checking result of the external clock
state.
0: External oscillation is in use
1: External oscillation is halted.
• When OSCBAKE = 0
This bit is meaningless. This bit is always read as 1.
0
CKSTA 0
R
LSI Operating Clock Status
0: This LSI operates on internal RC clock.
1: This LSI operates on external clock.
5.3 System Clock Select Operation
Figure 5.2 shows the state transition of the system clock.
Reset state
Reset release
LSI operates on internal RC clock
RC oscillator: Operated
External oscillator: Halted
Switching to
*
external clock
RC oscillator: Halted
External oscillator: Operated
RC oscillator halted
RC oscillator operated
RC oscillator: Operated
External oscillator: Operated
LSI operates on external oscillator
Note: *
Conditions for the state transition are as follows:
• When the external oscillation halt is detected while the backup function is enabled
• When the external clock is switched to the internal RC clock by user software while
the backup function is disabled
Figure 5.2 State Transition of System Clock
Rev. 1.00, 11/03, page 71 of 376