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'Help - I2C eeprom & write protection.'
1997\08\18@101709 by GERRY COX

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I am using a 16C63 together with a Microchip 24LC64 in a logger project. I2C
for the eeprom is derived from Microchips bit bashing routines found in
their application notes. During development I keep inadvertently setting the
security options, usually due to a program crash or when halting my
emulator. This  renders the memory device partly unwritable :-(

Is there any way of recovering a device by clearing the security feature. Is
there any way of preventing inadvertent writing or turning off thesecurity
feature entirely? I can't see the logic of not allowing it to be cleared
except to make more revenue for Microchip.

Thanks in advance,
Gerry Cox

1997\08\18@160222 by Antti Lukats

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At 02:52 PM 18/8/97 +0100, you wrote:
>I am using a 16C63 together with a Microchip 24LC64 in a logger project. I2C
>for the eeprom is derived from Microchips bit bashing routines found in
>their application notes. During development I keep inadvertently setting the
>security options, usually due to a program crash or when halting my
>emulator. This  renders the memory device partly unwritable :-(
>
>Is there any way of recovering a device by clearing the security feature. Is
>there any way of preventing inadvertent writing or turning off thesecurity
>feature entirely? I can't see the logic of not allowing it to be cleared
>except to make more revenue for Microchip.

I know now way of clearing the software CP after its set once.
it reads in DS 'one time' so it is supposed to be *one* time thing.

was worried myself when testing 24c65 programming routines, but I was lucky:
didnt set any CP bits by accident.

antti






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