Standby Function Operation; Halt Mode - NEC 78K0 User Manual

17.2 Standby Function Operation

17.2.1 HALT mode

(1) HALT mode
The HALT mode is set by executing the HALT instruction. HALT mode can be set regardless of whether the CPU
clock before the setting was the X1 input clock, Ring-OSC clock, or subsystem clock.
The operating statuses in the HALT mode are shown below.
HALT Mode Setting
Item
System clock
CPU
Port (latch)
16-bit timer/event counter 00
8-bit timer/event counter 50
8-bit timer/event counter 51
8-bit timer H0
8-bit timer H1
Watch timer
Watchdog Ring-OSC cannot
Note 4
timer be stopped
Ring-OSC can be
Note 4
stopped
A/D converter
Serial UART0
interface
UART6
CSI10
Clock monitor
Note 5
Power-on-clear function
Low-voltage detection function
External interrupt
Notes 1. When "Stopped by software" is selected for Ring-OSC by a mask option and Ring-OSC is stopped by
software (for mask options, see CHAPTER 22 MASK OPTIONS).
2. Operable when the X1 input clock is selected.
3. Operation not guaranteed when other than subsystem clock is selected.
4. "Ring-OSC cannot be stopped" or "Ring-OSC can be stopped by software" can be selected by a mask
option.
5. When "POC used" is selected by a mask option.
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CHAPTER 17 STANDBY FUNCTION
Table 17-2. Operating Statuses in HALT Mode (1/2)
When HALT Instruction Is Executed While CPU Is
Operating on X1 Input Clock
When Ring-OSC When Ring-OSC
Oscillation Continues Oscillation Stopped
When When When
Subsystem Subsystem Subsystem
Clock Used Clock Not Clock Used
Used
Clock supply to the CPU is stopped.
Operation stopped
Status before HALT mode was set is retained
Operable
Operable
Operable
Operable
Operable
Note 2
Operable Operable Operable
Operable
Operation stopped
Operable
Operable
Operable
Operable
Operable Operation stopped
Operable
Operable
Operable
User's Manual U16227EJ2V0UD
When HALT Instruction Is Executed While CPU Is
Operating on Ring-OSC Clock
When X1 Input Clock
Note 1
Oscillation Continues
When When When
Subsystem Subsystem Subsystem
Clock Not Clock Used Clock Not
Used Used
Operation not guaranteed
Operation not guaranteed when count clock other than
TI50 is selected
Operation not guaranteed when count clock other than
TI51 is selected
Operation not guaranteed when count clock other than
TM50 output is selected during 8-bit timer/event
counter 50 operation
Operation not guaranteed when count clock other than
7
f /2 is selected
R
Note 2 Note 3
Operable Operable Operation not
guaranteed
−
Operable
Operation not guaranteed
Operation not guaranteed when serial clock other than
TM50 output is selected during TM50 operation
Operation not guaranteed when serial clock other than
external SCK10 is selected
Operable
When X1 Input Clock
Oscillation Stopped
When When
Subsystem Subsystem
Clock Used Clock Not
Used
Note 3
Operable Operation not
guaranteed
Operation stopped