MC68LC302 Datasheet, PDF (42/169 Pages) Motorola, Inc – Low Power Integrated Multiprotocol Processor Reference Manual

System Integration Block (SIB)
1 = Synchronous accesses. All accesses to the IMP internal RAM and registers (in-
cluding BAR and SCR) must be synchronous to the IMP clock. Synchronous read
accesses may occur with one wait state if EMWS is also set to one.
RME—Ram Microcode Enable
This bit is used to initiate the execution of Communication Processor microcode that
has been loaded into the dual port RAM. See Appendix C in MC68302UM/AD.
VGE—Vector Generation Enable (Not supported by the MC68LC302)
This bit must be written to zero. Since the MC68LC302 cannot decode an interrupt ac-
knowledge cycle from an external processor without the FC pins, the user should provide
either an autovector signal or a vector back to the host processor during an interrupt ac-
knowledge cycle for the MC68LC302. The user should then read the IPR to determine
which the interrupt source.
3.1.4 Freeze Control
Used to freeze the activity of selected peripherals, FRZ is useful for system debugging pur-
poses (For more information on these bits, please refer to the MC68302 Users’ Manual):
FRZ1 — Freeze Timer 1 Enable
0 = Freeze Timer 1 Logic is disabled
1= Freeze Timer 1 Logic is enabled
After system reset this bit defaults to zero.
FRZ2 — Freeze Timer 2 Enable
0 = Freeze Timer 2 Logic is disabled
1= Freeze Timer 2 Logic is enabled
After system reset this bit defaults to zero.
FRZW — Freeze Watchdog Timer Enable
0 = Freeze Watchdog Timer Logic is disabled
1= Freeze Watchdog Timer Logic is enabled
After system reset this bit defaults to zero.
3.1.5 Hardware Watchdog
The hardware watchdog logic is used to assert an internal BERR and set HWT when a bus
cycle is not terminated by DTACK and after a programmable number of clock cycles has
elapsed. The hardware watchdog logic uses four bits in the SCR.
HWDEN—Hardware Watchdog Enable
0 = The hardware watchdog is disabled.
1 = The hardware watchdog is enabled.
After system reset, this bit defaults to one to enable the hardware watchdog.
MOTOROLA
MC68LC302 REFERENCE MANUAL
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