PD64A_15 Datasheet, PDF (24/66 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLERS FOR INFRARED REMOTE CONTROL TRANSMISSION

µPD64A, 65
5. STANDBY FUNCTION
5.1 Outline of Standby Function
To reduce current consumption, two types of standby modes, i.e., HALT mode and STOP mode, are available.
In STOP mode, the system clock stops oscillation. At this time, the XIN and XOUT pins are fixed at a low level.
In HALT mode, CPU operation halts, while the system clock continues oscillation. When in HALT mode, the
timer (including REM output and LED output) operates.
In either STOP mode or HALT mode, the statuses of the data memory, accumulator, and port register, etc.
immediately before the standby mode is set are retained. Therefore, make sure to set the port status for the system
so that the current consumption of the whole system is suppressed before the standby mode is set.
Table 5-1. Statuses in Standby Mode
Setting instruction
Clock oscillator
CPU
Data memory
Operation
Accumulator
statuses
Flag
F
CY
Port register
Timer
STOP Mode
HALT Mode
HALT instruction
Oscillation stopped
Oscillation continued
• Operation halted
• Immediately preceding status retained
• Immediately preceding status retained
• 0 (when 1, the flag does not enter the standby mode.)
• Immediately preceding status retained
• Immediately preceding status retained
• Operation halted
• Operable
(The count value is reset to “0”)
Cautions 1. Write the NOP instruction as the first instruction after STOP mode is released.
2. When standby mode is released, the status flag (F) is set (1).
3. If, at the point the standby mode has been set, its release condition is met, then the system
does not enter the standby mode. However, the status flag (F) is set (1).
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Data Sheet U14380EJ3V0DS00