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MSM80C154S/83C154S/85C154HVS
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4.9.3.2 Cancellation of CPU power down mode (IDLE, PD) by interrupt request signal
and restart from next address of stop address
To cancel idle mode (IDLE) or soft power down mode (PD) by interrupt request signal and
then resume execution from the next address after the stop address, “1” is set in bit 5 (RPD)
of the power control register. When “1” is set in this bit, the circuit connections shown in Figure
4-80 are made, and the CPU power down mode is cancelled when the interrupt flag has been
set to “1”, even if the entire contents of the interrupt enable register (IE 0A8H) have been put
into interrupt disable status.
All six interrupt sources can be used to cancel idle mode (IDLE). If an interrupt source is
generated and “1” is set in one of the interrupt flags in TCON, T2CON, or SCON, clock signals
are passed to the CPU control stage, and execution is resumed from the next address after
the stop address.
Soft power down mode (PD) can be cancelled by four different interrupt sources - external
interrupts 0 and 1 , and timer interrupts 0 and 1. The external interrupt flag is set by “0” level
being applied to either the INT0 or INT1 pin. And timer/counters 0 and 1 are used in external
clock mode. When one of the interrupt flags in TCON is set to “1”, XTAL1·2 operation is
commenced, and the program is executed from the next address after the stop address.
Note, however, that the interrupt flags are reset by software. The cancellation time charts are
shown in Figures 4-81 thru 4-84.
Figure 4-80 Equivalent circuit for power down mode cancellation and restart by interrupt
source signal
IE0 [TCON.1]
TF0 [TCON.5]
IE1 [TCON.3]
TF1 [TCON.7]
RI/TI [SCON.0, 1]
EXF2/TF2 [T2CON.6, 7]
IDLE, PD MODE
RESTART
Bit
Set
SMOD HPD RPD
—
GF1 GF0 PD IDL
76543210
•**
*MODE SET