96
5.3.4
Transition to Standby Mode and Pin States
The system goes from active (high-speed) mode or active (medium-speed) mode to standby
mode when a SLEEP instruction is executed while the SSBY bit in SYSCR1 is set to 1, the
LSON bit in SYSCR1 is cleared to 0, and bit TMA3 in TMA is cleared to 0. At the same time,
pins go to the high-impedance state (except pins with MOS pull-up turned on). The timing in
this case is shown in figure 5.2.
SLEEP instruction fetch
Internal
data bus
Next instruction fetch
Port output
Pins
High impedance
Active (high-speed) mode or active (medium-speed) mode
Standby mode
SLEEP instruction
execution
Internal
processing
ø
Figure 5.2 Transition to Standby Mode and Pin States