Datasheet

Resets and Interrupts
Resets
MC68HC912DT128A — Rev 4.0 Technical Data
MOTOROLA Resets and Interrupts 143
These registers can only be read in special modes (read in normal mode
will return $00). Reading these registers at the same time as the interrupt
is changing will cause an indeterminate value to be read. These
registers can only be written in special mode.
10.8 Resets
There are four possible sources of reset. Power-on reset (POR), and
external reset on the RESET
pin share the normal reset vector. The
computer operating properly (COP) reset and the clock monitor reset
each has a vector. Entry into reset is asynchronous and does not require
a clock but the MCU cannot sequence out of reset without a system
clock.
10.8.1 Power-On Reset
A positive transition on V
DD
causes a power-on reset (POR). An external
voltage level detector, or other external reset circuits, are the usual
ITST0 — Interrupt Test Register 0 $0018
Bit 7654321Bit 0
ITE6 ITE8 ITEA ITEC ITEE ITF0 ITF2 ITF4
RESET: 0 0000000
ITST1 — Interrupt Test Register 1 $0019
Bit 7654321Bit 0
ITD6 ITD8 ITDA ITDC ITDE ITE0 ITE2 ITE4
RESET: 0 0 0 0 0 0 0 0
ITST2 — Interrupt Test Register 2 $001A
Bit 7654321Bit 0
ITC6 ITC8 ITCA ITCC ITCE ITD0 ITD2 ITD4
RESET: 0 0 0 0 0 0 0 0
ITST3 — Interrupt Test Register 3 $001B
Bit 7654321Bit 0
ITB6 ITB8 ITBA ITBC ITBE ITC0 ITC2 ITC4
RESET: 00000000
Frees
cale Semiconductor,
I
Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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