84
CHAPTER 7 RESET
7.1
Reset Operation
When a reset factor occurs, the CPU stops the current execution immediately and
enters the reset release wait state. When the device is released from the reset, the CPU
reads mode data and the reset vector from internal ROM (mode fetch). When the power
is turned on or when the device is released from a reset in subclock mode or stop
mode, the CPU performs mode fetch after the oscillation stabilization wait time has
passed.
■
Reset Factors
Resets are classified into five reset factors.
●
External reset
An external reset is generated upon "L" level input to the external reset pin (RST).
An externally input reset signal is accepted asynchronously via the internal noise filter and generates an
internal reset signal in synchronization with the machine clock to initialize the internal circuit.
Consequently, a clock is necessary for internal circuit initialization. Clock input is therefore necessary for
operation with an external clock.
Note, however, that external pins (including I/O ports and peripheral resources) are reset asynchronously.
Additionally, there are standard pulse-width values for external reset input. If the value is below the
standard, the reset may not be accepted. The standard value is listed on the data sheet. Please design your
external reset circuit so that this standard is met.
●
Software reset
Writing "1" to the software reset bit of the standby control register (STBC:SRST) generates a software
reset.
●
Watchdog reset
After the watchdog timer starts, a watchdog reset is generated if the watchdog timer is not cleared within a
preset amount of time.
Table 7.1-1 Reset Factors
Reset Factor
Reset Condition
External reset
"L" level input to the external reset pin
Software reset
"1" is written to the software reset bit (STBC: SRST) in the standby control
register.
Watchdog reset
The watchdog timer causes an overflow.
Power-on reset/
low-voltage detection reset
The power is turned on or the supply voltage falls below the detected voltage.
Clock supervisory reset
Oscillation stops abnormally, not caused by a predefined state transition.
Summary of Contents for F2 MC-8FX Family
Page 2: ......
Page 4: ......
Page 34: ...20 CHAPTER 1 DESCRIPTION ...
Page 38: ...24 CHAPTER 2 HANDLING DEVICES ...
Page 39: ...25 CHAPTER 3 MEMORY SPACE This chapter describes memory space 3 1 Memory Space 3 2 Memory Map ...
Page 56: ...42 CHAPTER 5 CPU ...
Page 73: ...59 CHAPTER 6 CLOCK CONTROLLER ...
Page 96: ...82 CHAPTER 6 CLOCK CONTROLLER ...
Page 104: ...90 CHAPTER 7 RESET ...
Page 105: ...91 CHAPTER 8 INTERRUPTS This chapter explains the interrupts 8 1 Interrupts ...
Page 174: ...160 CHAPTER 10 TIMEBASE TIMER ...
Page 184: ...170 CHAPTER 10 TIMEBASE TIMER ...
Page 218: ...204 CHAPTER 13 WATCH PRESCALER ...
Page 257: ...243 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 261: ...247 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 288: ...274 CHAPTER 16 8 16 BIT COMPOSITE TIMER ...
Page 301: ...287 CHAPTER 17 16 BIT PPG TIMER ...
Page 316: ...302 CHAPTER 17 16 BIT PPG TIMER ...
Page 382: ...368 CHAPTER 21 UART SIO DEDICATED BAUD RATE GENERATOR ...
Page 390: ...376 CHAPTER 22 I2C ...
Page 395: ...381 CHAPTER 22 I2C ...
Page 399: ...385 CHAPTER 22 I2C ...
Page 430: ...416 CHAPTER 23 10 BIT A D CONVERTER ...
Page 476: ...462 CHAPTER 24 LCD CONTROLLER ...
Page 482: ...468 CHAPTER 25 LOW VOLTAGE DETECTION RESET CIRCUIT ...
Page 494: ...480 CHAPTER 26 CLOCK SUPERVISOR ...
Page 507: ...493 CHAPTER 27 REAL TIME CLOCK ...
Page 523: ...509 CHAPTER 27 REAL TIME CLOCK ...
Page 532: ...518 CHAPTER 27 REAL TIME CLOCK ...
Page 536: ...522 CHAPTER 28 256 KBIT FLASH MEMORY ...
Page 554: ...540 CHAPTER 28 256 KBIT FLASH MEMORY ...
Page 564: ...550 CHAPTER 29 EXAMPLE OF SERIAL PROGRAMMING CONNECTION ...
Page 595: ...581 INDEX INDEX The index follows on the next page This is listed in alphabetic order ...
Page 596: ...582 INDEX Index ...
Page 597: ...583 INDEX ...
Page 600: ...586 Pin Function Index ...
Page 602: ......