upd64a Renesas Electronics Corporation., upd64a Datasheet - Page 22

• Manufacturer Part Number: upd64a
• Description: 4-bit Single-chip Microcontroller For Infrared Remote Control Transmission
• Manufacturer: Renesas Electronics Corporation.

5. STANDBY FUNCTION
5.1 Outline of Standby Function
timer (including REM output and LED output) operates.
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.
22
Setting instruction
Clock oscillator
Operation
statuses
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 X
In HALT mode, CPU operation halts, while the system clock continues oscillation. When in HALT mode, the
In either STOP mode or HALT mode, the statuses of the data memory, accumulator, and port register, etc.
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
CPU
Data memory
Accumulator
Flag
Port register
Timer
does not enter the standby mode. However, the status flag (F) is set (1).
F
CY
Table 5-1. Statuses in Standby Mode
Oscillation stopped
• Operation halted
• 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
HALT instruction
• Immediately preceding status retained
(The count value is reset to “0”)
Data Sheet U14380EJ3V0DS00
STOP Mode
IN
and X
Oscillation continued
• Operable
OUT
pins are fixed at a low level.
HALT Mode
PD64A, 65