MC68HC11PH8 Datasheet, PDF (75/264 Pages) Motorola, Inc – High-density Complementary Metal Oxide Semiconductor (HCMOS) Microcomputer Unit

PH8.DS03/Modes+mem
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3.4.3 CONFIG register programming
Because the CONFIG register is implemented with EEPROM cells, use EEPROM procedures to
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erase and program this register. The procedure for programming is the same as for programming
a byte in the EEPROM array, except that the CONFIG register address is used. CONFIG can be
programmed or erased (including byte erase) while the MCU is operating in any mode, provided
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that PTCON in BPROT is clear. To change the value in the CONFIG register, complete the
following procedure. Do not initiate a reset until the procedure is complete.
1) Erase the CONFIG register.
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2) Program the new value to the CONFIG address.
3) Initiate reset.
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CONFIG — System configuration 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
For a description of the bits contained in the CONFIG register refer to Section 3.3.2.1.
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 is readable or active until latched via the next reset.
FREEZ is only active in expanded user mode.
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MC68HC11PH8
OPERATING MODES AND ON-CHIP MEMORY
¬^TPG
MOTOROLA
3-29
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