MC68HC705JJ7 Datasheet, PDF (123/164 Pages) Freescale Semiconductor, Inc – Microcontrollers

EPROM Erasing
13.3.1 MOR Programming
The contents of the MOR should be programmed using the programmer board. To program any bits in
the MOR, the desired bit states must be written to the MOR address and then the MPGM bit in the EPROG
register must be used. The following sequence will program the MOR:
1. Write the desired data to the MOR location ($1FF1).
2. Apply the programming voltage to the IRQ/V_PP pin.
3. Set the MPGM bit in the EPROG.
4. Wait for the programming time, t_MPGM.
5. Clear the MPGM bit in the EPROG.
6. Remove the programming voltage from the IRQ/V_PP pin.
Once the MOR bits have been programmed, some of the options may experience glitches in operation
after removal of the programming voltage. It is recommended that the part be reset before trying to verify
the contents of the user EPROM or the MOR itself.
NOTE
The contents of the EPROM or the MOR cannot be accessed if the
EPMSEC bit in the COPR register has been set.
13.3.2 EPMSEC Programming
The EPMSEC bit is programmable. To program the EPMSEC bit, the desired state must be written to the
COP address and then the MPGM bit in the EPROG register must be used. The following sequence will
program the EPMSEC bit:
1. Write the desired data to bit 7 of the COPR location ($1FF0).
2. Apply the programming voltage to the IRQ/V_PP pin.
3. Set the MPGM bit in the EPROG.
4. Wait for the programming time, t_MPGM.
5. Clear the MPGM bit in the EPROG.
6. Remove the programming voltage from the IRQ/V_PP pin.
Once the EPMSEC bit has been programmed to a logic 1, access to the contents of the EPROM and MOR
in the expanded non-user modes will be denied. It is therefore recommended that the user EPROM and
MOR in the part first be programmed and fully verified before setting the EPMSEC bit.
13.4 EPROM Erasing
MCUs with windowed packages permit EPROM erasing with ultraviolet light. Erase the EPROM by
exposing it to 15 Ws/cm² of ultraviolet light with a wavelength of 2537 angstroms. Position the ultraviolet
light source 1 inch from the window. Do not use a shortwave filter. The erased state of an EPROM bit is
a logic 0.
NOTE
Unlike many commercial EPROMs, an erased EPROM byte in the MCU will
read as $00. All unused locations should be programmed as 0s.
MC68HC705JJ7 • MC68HC705JP7 Advance Information Data Sheet, Rev. 4.1
Freescale Semiconductor
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