AN2156 Freescale Semiconductor / Motorola, AN2156 Datasheet - Page 8

• Manufacturer Part Number: AN2156
• Description: Programming and Erasing FLASH and EEPROM Memories on the MC68HC908AS60A/AZ60A
• Manufacturer: Freescale Semiconductor / Motorola

Application Note
FLASH Block Protection
8
NOTE:
NOTE:
The 64-byte row address boundaries for the MC68HC908AS60A/AZ60A
are:
When programming the FLASH, exact programming time must be used
to program a row. Excessive program time can result in a program
disturb condition, in which case an erased bit on the row being
programmed becomes unintentionally programmed. Program disturb is
avoided by using the recommended algorithm. See
Operation.
A security feature prevents viewing of the FLASH contents.
Programming tools are available from Motorola. Contact a local Motorola
representative for more information.
To protect the contents in the FLASH array from being inadvertently
programmed or erased by run-away code in the user application, the
FLASH block protect register option was implemented. This register is
composed of two nonvolatile bytes within the FLASH-1 array, with one
byte per FLASH array. Once the block protect bits are set in the FLxBPR
registers, the defined address ranges are protected from being
programmed or erased. See
of address ranges.
However, If a protected memory block needs to be programmed or
erased, the block protection can be overridden by applying the voltage
V
The vector locations and FLxBPR registers are located in the same
page. The FLxPBR registers are not protected with special hardware or
software. Therefore, if the page is not protected by the FL1BPR and the
vector locations are erased by either page or mass erase operation, both
FL1BPR and FL2BPR registers are also erased.
1. No security feature is absolutely secure. However, Motorola’s strategy is to make reading or
copying the FLASH difficult for unauthorized users.
H
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Freescale Semiconductor, Inc.
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on the IRQ pin during the erase and program operations.
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FLASH Block Protection
FLASH Program
for a description
1
MOTOROLA
AN2156