UPD784026 Renesas Electronics Corporation., UPD784026 Datasheet - Page 671

• Manufacturer Part Number: UPD784026
• Description: 16/8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

22.5 IDLE MODE
22.5.1 IDLE Mode Setting and Operating States
mode setting is therefore performed by means of the “MOV STBC, #byte” instruction.
released). Otherwise, several instructions may be executed after the IDLE mode has been released and before the interrupt
is acknowledged. This may change the sequential relation between interrupt processing and instruction execution, and
cause a problem.
The IDLE mode is selected by setting (1) both the STP bit and the HLT bit of the standby control (STBC) register.
The only writes that can be performed on the STBC are 8-bit data writes by means of a dedicated instruction. IDLE
Write an NOP instruction three times after the instruction that has set the IDLE mode (or after the IDLE mode has been
Caution If the IDLE mode is set when the condition to release the HALT mode is satisfied (refer to 22.3.2 HALT
* A/D converter operation is stopped, but if the CS bit of the A/D converter mode register (ADM) is set, the current
Cautions 1. The CS bit of the A/D converter mode (ADM) register should be reset.
consumption does not decrease. D/A converter operation is not stopped.
Mode Release), the IDLE mode is not set, but the next instruction is executed or execution branches
to a vectored interrupt service program. To accurately set the IDLE mode, clear the interrupt request
before setting the IDLE mode.
2. D/A converter operation is not stopped simply by setting the IDLE mode. In order to reduce the
current consumption, the DACEn (n = 0, 1) bits of the D/A converter mode register (DAM) must
both be cleared (0). When DACEn is cleared (0), the ANOn (n = 0, 1) pin output level becomes high-
impedance.
Clock oscillator
Internal system clock
CPU
I/O lines
Peripheral functions
Internal RAM
Bus lines
RD, WR output
ASTB output
REFRQ output
HLDRQ input
HLDAK output
Table 22-6 Operating States in IDLE Mode
AD0 to AD7
A8 to A19
CHAPTER 22 STANDBY FUNCTION
Oscillation continues
Stopped
Operation stopped
Retain state prior to IDLE mode setting
All operation stopped*
Retained
High-impedance
High-impedance
High-impedance
High-impedance
Retained
Hihg-impedance
Low level
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