MC912DG128ACPVE Datasheet, PDF (143/478 Pages) Freescale Semiconductor, Inc – Upward compatible with M68HC11 instruction set

Freescale Semiconductor, Inc.
Resets and Interrupts
Resets
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.
ITST0 — Interrupt Test Register 0
RESET:
Bit 7
ITE6
0
6
ITE8
0
5
ITEA
0
4
ITEC
0
3
ITEE
0
2
ITF0
0
1
ITF2
0
Bit 0
ITF4
0
$0018
ITST1 — Interrupt Test Register 1
RESET:
Bit 7
ITD6
0
6
ITD8
0
5
ITDA
0
4
ITDC
0
3
ITDE
0
2
ITE0
0
1
ITE2
0
Bit 0
ITE4
0
$0019
ITST2 — Interrupt Test Register 2
RESET:
Bit 7
ITC6
0
6
ITC8
0
5
ITCA
0
4
ITCC
0
3
ITCE
0
2
ITD0
0
1
ITD2
0
Bit 0
ITD4
0
$001A
ITST3 — Interrupt Test Register 3
RESET:
Bit 7
ITB6
0
6
ITB8
0
5
ITBA
0
4
ITBC
0
3
ITBE
0
2
ITC0
0
1
ITC2
0
Bit 0
ITC4
0
$001B
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
MC68HC912DT128A — Rev 4.0
MOTOROLA
Resets and Interrupts
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Technical Data
143