Texas Instruments MSC1210 - Manual (Page 191)

Power Optimization
15-9
Advanced Topics
15.4 Power Optimization
The MSC1210, like a standard 8052, has the ability to operate in a
power-saving mode, known as idle mode. As the name implies, idle mode
shuts down most of the energy-consuming functions of the microcontroller and
idles. Code execution stops in idle mode, and the only way to exit idle mode
is a system reset or an enabled interrupt being triggered.
Idle mode is useful in causing the microcontroller to go to sleep until an inter-
rupt awakens it. Instead of cycling repeatedly waiting for an interrupt condition
to occur, the part may be made to go to sleep until the condition is triggered—
during that time, power consumption is minimized. External interrupts, the
watchdog interrupt, or the auxiliary interrupts can be made to wake up an idling
MSC1210.
To enter idle mode, bit 0 of PCON must be set. This can be accomplished with
the instruction:
PCON |= 0x01;
When this instruction is executed, the MSC1210 immediately drops into idle
mode and remains there until an enabled interrupt occurs. When an interrupt
occurs, the ISR executes and finishes, and program execution continues with
the instruction following the instruction that put the MSC1210 in idle mode—in
this case, the instruction mentioned previously.