MC68HC705JP7 Datasheet, PDF (180/242 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Personality EPROM (PEPROM)
The PEPROM can also be programmed by user software with the V_PP
voltage level applied to the IRQ/V_PP 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, t_EPGM.
4. Clear the PEPGM bit.
5. Move to next PEPROM bit to be programmed in step 1.
12.5 PEPROM Reading
This sequence shows how to read the PEPROM:
1. Select a bit by writing to the PEBSR.
2. Read the PEDATA bit in the PESCR.
3. Store the PEDATA bit in RAM or in a register.
4. Select another bit by changing the PEBSR.
5. Continue reading and storing the PEDATA bits until the required
personality EPROM data is retrieved and stored.
Reading the PEPROM is easiest when each PEPROM column contains
one byte. Selecting a row 0 bit selects the first bit, and incrementing the
PEPROM bit select register (PEBSR) selects the next bit in row 1 from
the same column. Incrementing PEBSR seven more times selects the
remaining bits of the column and ends up selecting the bit in row 0 of the
next column, thereby setting the row 0 flag, PEPRZF.
NOTE:
A PEPROM byte that has been read can be transferred to the personality
EPROM bit select register (PEBSR) as a temporary storage location
such that subsequent reads of the PEBSR quickly yield that PEPROM
byte.
Advance Information
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MC68HC705JJ7 • MC68HC705JP7 — REV 4
Personality EPROM (PEPROM)
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