MC68HC11PH8 Datasheet, PDF (190/264 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

10.1.6 CONFIG — Configuration control register
ConÞguration control (CONFIG)
Address bit 7
bit 6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
State
on reset
$003F ROMAD FREEZ CLK4X PAREN NOSEC NOCOP ROMON EEON xxxx xxxx
Among other things, CONFIG controls the presence and location of EEPROM in the memory map
and enables the COP watchdog system. A security feature that protects data in EEPROM and
RAM is available on mask programmed MCUs.
CONFIG is made up of EEPROM cells and static working latches. The operation of the MCU is
controlled directly by these latches and not the EEPROM byte. When programming the CONFIG
register, the EEPROM byte is accessed. When the CONFIG register is read, the static latches
are accessed.
These bits can be read at any time. The value read is the one latched into the register from the
EEPROM cells during the last reset sequence. A new value programmed into this register is not
readable until after a subsequent reset sequence.
On the MC68HC711PH8, and on the MC68HC11PH8 if selected by a mask option, the ROMON
bit can be written at any time if MDA = 1 (expanded mode or special test mode). It cannot be
written in bootstrap mode, and is forced to a logic one in single chip mode.
Other bits in CONFIG can be written at any time if SMOD = 1 (bootstrap or special test mode). If
SMOD = 0 (single chip or expanded mode), these bits can only be written using the EEPROM
programming sequence, and none of the bits are readable or active until latched via the next reset.
FREEZ is only active in expanded user mode.
10
ROMAD — ROM/EPROM mapping control (refer to Section 3)
1 (set) – ROM addressed from $4000 to $FFFF.
0 (clear) – ROM addressed from $0000 to $BFFF (expanded mode only).
In single chip mode, reset sets this bit.
FREEZ — Expanded user mode address bus freeze (refer to Section 3)
1 (set) – The external bus is only active when externally mapped resources
are accessed (expanded mode only)
0 (clear) – Normal operation.
CLK4X — 4X clock enable (refer to Section 3)
1 (set) – 4XCLK or EXTALi driven out on the 4XOUT pin.
0 (clear) – 4XOUT pin disabled.
MOTOROLA
10-6
RESETS AND INTERRUPTS
TPG
MC68HC11PH8