MC68HC908GT16_07 FREESCALE [Freescale Semiconductor, Inc], MC68HC908GT16_07 Datasheet - Page 46

• Manufacturer Part Number: MC68HC908GT16_07
• Description: Microcontrollers
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

Memory
2.6.8 ICG User Trim Registers (ICGTR5 and ICGTR3)
The ICG user trim register are two normal bytes of Flash memory which are allocated for the user to store
copies of the ICG trim register (ICGTR) value. ICGTR5 is allocated for storage of the trim value when a
5-V supply is used, ICGTR3 for storage of the trim value when a 3-V supply is used. Representative trim
values are programmed into these locations by Freescale but they may be erased and reprogrammed by
the user at any time.
Storage and retrieval of data in these registers is not automatic and must be performed programmatically.
Typically, these locations are programmed by the user during an in-system calibration procedure and one
of them, depending on the application supply voltage, is subsequently used by the user’s initialization
code to configure the ICG each time following a reset.
ICGTR5 is used by the MC68HC908GT16 monitor ROM program during its initialization sequence if
monitor mode was entered while clocking from the ICG. If the contents of ICGTR5 are not $FF then the
contents are copied to ICGTR.
TRIM[7:0] — ICG Trim Factor Bits
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These bits are copied by the monitor ROM program following a reset, if monitor mode was entered
while clocking from the ICG and may be copied by the user’s initialization code to the ICG trim register
(ICGTR).
Address: ICGTR5, $FF80 and ICGTR3, $FF81
The contents of ICGTR3 are not utilized by the monitor ROM program.
Reset:
Read:
Write:
MC68HC908GT16 • MC68HC908GT8 • MC68HC08GT16 Data Sheet, Rev. 5.0
Figure 2-7. ICG User Trim Registers (ICGTR5 and ICGTR3)
Write to this register is by a programming sequence to the Flash memory.
$FC (1111 1100)
$FD (1111 1101)
$FE (1111 1110)
$01 (0000 0001)
$02 (0000 0010)
$03 (0000 0011)
$04 (0000 0100)
TRIM7
Bit 7
BPR[7:0]
Table 2-2. Examples of Protect Address Ranges
$FF
$00
TRIM6
6
Unaffected by reset. Initial value from factory is 1.
TRIM5
5
The entire Flash memory is not protected.
$C0C0 (1100 0000 1100 0000) — $FFFF
$C040 (1100 0000 0100 0000) — $FFFF
$C080 (1100 0000 1000 0000) — $FFFF
$C100 (1100 0001 0000 0000) — $FFFF
$FF40 (1111 1111 0100 0000) — $FFFF
$FF00 (1111 1111 0000 0000) — FFFF
$FF80 (1111 1111 1000 0000) — FFFF
The entire Flash memory is protected.
and so on...
FLBPR and vectors are protected
NOTE
Addresses of Protect Range
TRIM4
4
Vectors are protected
TRIM3
3
TRIM2
2
TRIM1
1
Freescale Semiconductor
TRIM0
Bit 0