can imperfect power reset damage flash programmable HC08 ?

Dear all,

Can an imperfect power off reset, with the power supply going down to 0.5 V instead of required 0.1 V, damage flash programmable HC08 chips?

I have made a board with a micro and a RS232 line driver amongst other things, and I have been using Metrowerks to download the code. It worked ok for some time, it went to a few dozens of programming/debugging cycles, say 30, and then it become dead (for the Metrowerks).

Later on, trying to see what happened, I have noticed that my power off reset did not bring the power supply for the HC08 down to 0.1V but only down to about 0.5 V (a leak from an overseen pull-up elsewhere on the board

- embarrassing). The chip itself does not seem to have shorted pins neither to the ground nor to the supply, and I haven't been able to find any other electrical fault.

Another thing the chip suffered is that I tried to perform bit set and bit clear using 2 byte addresses. I had detected it while the chip was still ok, and corrected it, went through two or three more programming cycles, and then the chip stopped responding.

I shall try replacing the chip presently, but would anyone care to comment on what could have gone wrong, and why? All comments welcome.

Reply to
Judges1318
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Some early versions of the GP32 did have a bug in the undervoltage circuit. Look for the erratasheet at the freescale website.

Do one or more times masserase with a programmer, usually the chip works again. There is some cryptic information in the datasheet/Electrical Specifications about odd limits in the programming/erasing cycles.

On the topic of 68HC08 bugs: has anyone got the I2C-bus module on the AP working with lets say an external serial EEPROM ?

MfG JRD

Reply to
Rafael Deliano

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