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MC68HC705JJ7 Datasheet, PDF (117/164 Pages) Freescale Semiconductor, Inc – Microcontrollers
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PEPROM Programming
PEPGM — PEPROM Program Control Bit
This read/write bit controls the switches that apply the programming voltage from the IRQ/VPP pin to
the selected PEPROM bit cell. When the PEPGM bit is set, the selected bit cell will be programmed to
a logic 1, regardless of the state of the PEDATA bit. Reset clears the PEPGM bit.
1 = Programming voltage applied to array bit
0 = Programming voltage not applied to array bit
PEPRZF — PEPROM Row Zero Flag
This read-only bit is set when the PEPROM bit select register selects the first row (row zero) of the
PEPROM array. Selecting any other row clears PEPRZF. Monitoring PEPRZF can reduce the code
needed to access one byte of eight PEPROM locations. Reset clears the PEPROM bit select register,
thereby setting the PEPRZF bit by default.
1 = Row zero selected
0 = Row zero not selected
Table 12-1. PEPROM Bit Selection
PEBSR
$00
$01
|
V
$07
$08
$09
|
V
$37
$38
$39
|
V
$3E
$3F
PEPROM Bit Selected
Row 0
Row 1
|
V
Row 7
Row 0
Row 1
|
V
Row 7
Row 0
Row 1
|
V
Row 6
Row 7
Column 0
Column 0
|
V
Column 0
Column 1
Column 1
|
V
Column 6
Column 7
Column 7
|
V
Column 7
Column 7
12.3 PEPROM Programming
Factory-provided software for programming the PEPROM is available on the World Wide Web at:
http://www.freescale.com
NOTE
While the PEPGM bit is set and the VPP voltage level is applied to the
IRQ/VPP pin, do not access bits that are to be left unprogrammed (erased).
To program the PEPROM bits properly, the VDD voltage must be greater
than 4.5 Vdc.
The PEPROM can also be programmed by user software with the VPP voltage level applied to the
IRQ/VPP pin. This sequence shows how to program each PEPROM bit:
1. Select a PEPROM bit by writing to the PEBSR.
2. Set the PEPGM bit in the PESCR.
3. Wait for the programming time, tEPGM.
4. Clear the PEPGM bit.
5. Move to next PEPROM bit to be programmed in step 1.
MC68HC705JJ7 • MC68HC705JP7 Advance Information Data Sheet, Rev. 4.1
Freescale Semiconductor
117
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