PD17225_15 Datasheet, PDF (48/86 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCONTROLLER FOR SMALL GENERAL-PURPOSE INFRARED REMOTE CONTROL TRANSMITTER

µPD17225, 17226, 17227, 17228
8. STANDBY FUNCTIONS
µPD17225 is provided with HALT and STOP modes as standby functions. By using the standby function, current
consumption can be reduced.
In the HALT mode, the program is not executed, but the system clock fX is not stopped. This mode is main-
tained, until the HALT mode release condition is satisfied.
In the STOP mode, the system clock is stopped and program execution is stopped. This mode is maintained, until the
STOP mode release condition is satisfied.
The HALT mode is set, when the HALT instruction has been executed. The STOP mode is set, when the STOP
instruction has been executed.
8.1 HALT Mode
In this mode, program execution is temporarily stopped, with the main clock continuing oscillating, to reduce current
consumption. Use the HALT instruction to set the HALT mode.
The HALT mode releasing condition can be specified by the operand for the HALT instruction, as shown in Table
8-1.
After the HALT mode has been released, the operation is performed as shown in Table 8-1 and Figure 8-2.
Caution Do not execute an instruction that clears the interrupt request flag (IRQ×××) for which the interrupt
enable flag (IP×××) is set immediately before the HALT 8H instruction; otherwise, the HALT mode
may not be set.
Table 8-1. HALT Mode Releasing Conditions
Operand Value
0010B (02H)
1000B (08H)
Other Than Above
Releasing Conditions
When interrupt request (IRQTM) occurs for 8-bit timer
<1> When interrupt request (IRQTM, IRQWTM, or IRQ), whose interrupt enable flag (IPTM,
IPBTM, or IP) is set, occurs
<2> When any of P0A0-P0A3 and P0B0-P0B3 pins goes low
Setting prohibited
Table 8-2. Operations After HALT Mode Release (1/2)
(a) HALT 08H
HALT Mode Released by:
Low-Level Input of P0A0-P0A3,
P0B0-P0B3
When Release Condition Is
Satisfied by Interrupt
Interrupt Status
Don’t care
Interrupt Enable Flag
Don’t care
Operations after HALT Mode Release
Instruction next to HALT is executed
DI
Disabled
Standby mode is not released
Enabled
Instruction next to HALT is executed
EI
Disabled
Standby mode is not released
Enabled
Branches to interrupt vector address
46
Data Sheet U12643EJ2V0DS00