MC68HC908JK1 Datasheet, PDF (76/210 Pages) Motorola, Inc – MC68HC908JK1

System Integration Module (SIM)
In wait mode, the CPU clocks are inactive. The SIM also produces two
sets of clocks for other modules. Refer to the wait mode subsection of
each module to see if the module is active or inactive in wait mode.
Some modules can be programmed to be active in wait mode.
7.4 Reset and System Initialization
The MCU has these reset sources:
• Power-on reset module (POR)
• External reset pin (RST)
• Computer operating properly module (COP)
• Low-voltage inhibit module (LVI)
• Illegal opcode
• Illegal address
All of these resets produce the vector $FFFE–FFFF ($FEFE–FEFF in
Monitor mode) and assert the internal reset signal (IRST). IRST causes
all registers to be returned to their default values and all modules to be
returned to their reset states.
An internal reset clears the SIM counter (see 7.5 SIM Counter), but an
external reset does not. Each of the resets sets a corresponding bit in
the reset status register (RSR). (See 7.8 SIM Registers.)
7.4.1 External Pin Reset
The RST pin circuits include an internal pull-up device. Pulling the
asynchronous RST pin low halts all processing. The PIN bit of the reset
status register (RSR) is set as long as RST is held low for a minimum of
67 2OSCCLK cycles, assuming that the POR was not the source of the
reset. See Table 7-2 for details. Figure 7-4 shows the relative timing.
Reset Type
POR
All others
Table 7-2. PIN Bit Set Timing
Number of Cycles Required to Set PIN
4163 (4096 + 64 + 3)
67 (64 + 3)
Technical Data
76
System Integration Module (SIM)
MC68H(R)C908JL3 — Rev. 1.0
MOTOROLA