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µPD750008 USER'S MANUAL
7.4 SELECTION OF A MASK OPTION
For the standby function of the µPD750008, either of the following two values can be selected by a mask
option as the wait time during which the start of oscillation deferred from the generation of a RESET signal:
<1> 217/fX (21.8 ms at 6.00 MHz, 31.3 ms at 4.19 MHz)
<2> 215/fX (5.46 ms at 6.00 MHz, 7.81 ms at 4.19 MHz)
However, the µPD75P0016 dose not have a mask option and its wait time is fixed to 215/fX.
7.5 APPLICATIONS OF THE STANDBY MODES
When the standby modes are used, the following steps are used.
<1> Detect a standby mode setting factor such as power removal on an interrupt input or port input. (INT4
is useful for power removal detection.)
<2> Configure I/O ports for minimum current drain.
<3> Specify interrupts for releasing a standby mode. (INT4 is useful. All interrupt enable flags not used
for release are to be cleared.)
<4> Specify an operation to be performed after release. (IME is to be manipulated according to whether
interrupt processing is performed or not.)
<5> Specify a CPU clock to be used after release. (If the CPU clock is changed, required machine cycles
must elapse before the standby mode is set.)
<6> Select a wait time to be used when a standby mode is released.
<7> Set a standby mode using a STOP or HALT instruction.
A standby mode when combined with the system clock switch function enables a lower power consumption
and lower-voltage operation.
(1) Application of the STOP mode (at fX = 4.19 MHz)
<Use of the STOP mode under the following conditions>
The STOP mode is set on the falling edge of INT4, and is released on the rising edge of INT4. (INTBT
is not used.)
All I/O ports have a high impedance.
The INT0 and INTT0 interrupts are used for the program, but are not used to release the STOP mode.
After the STOP mode is released, interrupts are enabled.
After the STOP mode is released, the lowest-speed CPU clock is used for operation. Then, the CPU
clock is changed to the high-speed one after 250 ms.
A wait time used when the STOP mode is released is about 31.3 ms.
After the STOP mode is released, another wait time of 31.3 ms is used for stable power supply operation.
The P00/INT4 pin is checked twice to remove chattering.