參數(shù)資料
型號: MC68HC08QT1MDWE
廠商: FREESCALE SEMICONDUCTOR INC
元件分類: 微控制器/微處理器
英文描述: 8-BIT, FLASH, 8 MHz, MICROCONTROLLER, PDSO8
封裝: LEAD FREE, EIAJ, SOIC-8
文件頁數(shù): 9/176頁
文件大?。?/td> 1124K
代理商: MC68HC08QT1MDWE
System Integration Module (SIM)
MC68HC08QY/QT Family Data Sheet, Rev. 2
106
Freescale Semiconductor
13.4.2 Active Resets from Internal Sources
The RST pin is initially setup as a general-purpose input after a POR. Setting the RSTEN bit in the
CONFIG2 register enables the pin for the reset function. This section assumes the RSTEN bit is set when
describing activity on the RST pin.
NOTE
For POR and LVI resets, the SIM cycles through 4096 BUSCLKX4 cycles.
The internal reset signal then follows the sequence from the falling edge of
RST shown in Figure 13-4.
The COP reset is asynchronous to the bus clock.
The active reset feature allows the part to issue a reset to peripherals and other chips within a system
built around the MCU.
All internal reset sources actively pull the RST pin low for 32 BUSCLKX4 cycles to allow resetting of
external peripherals. The internal reset signal IRST continues to be asserted for an additional 32 cycles
(see Figure 13-4). An internal reset can be caused by an illegal address, illegal opcode, COP time out,
LVI, or POR (see Figure 13-5).
Figure 13-4. Internal Reset Timing
Figure 13-5. Sources of Internal Reset
Table 13-2. Reset Recovery Timing
Reset Recovery Type
Actual Number of Cycles
POR/LVI
4163 (4096 + 64 + 3)
All others
67 (64 + 3)
IRST
RST
RSTPULLEDLOWBYMCU
ADDRESS
32 CYCLES
VECTOR HIGH
BUSCLKX4
BUS
ILLEGAL ADDRESS RST
ILLEGAL OPCODE RST
COPRST
POR
LVI
INTERNAL RESET
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