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Hi, A batch of 68HC711 was programmed but the program is now obsolete and I would like to recycle them as regular 68HC11E9 's. I tried to disable the EPROM through the config register, but somehow the EPROM seems to be present even with the changed CONFIG reg. The CPU starts up in expanded multiplexed. The pink book states that the EPROM will always be switched ON when the chip starts up in single-chip mode, but nothing is said about expanded mux mode. Has anyone tried this before, what should I do to get rid of the EPROM in the memory map? Jaap.

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Because we can't know exactly what you did, to verify, you've zeroed the ROMON (Bit1) and not the EEON bit in CONFIG ($103F) using the recommended EEPROM programming algorithm (which erases first, then programs), then started the MCU in expanded mode and you can still see the internal memory from $D000 to $FFFF? Was the BPROT register written from boot mode to allow CONFIG reprogramming (with bit PTCON [Bit4] zeroed) before attempting to erase or reprogram CONFIG? If all is right, it should work. ----- Original Message ----- From: Jaap <> To: <> Sent: Thursday, October 31, 2002 4:39 PM Subject: [m68HC11] recycling 68HC711E9 > Hi, > > A batch of 68HC711 was programmed but the program is now obsolete and I > would like to recycle them as regular 68HC11E9 's. I tried to disable the > EPROM through the config register, but somehow the EPROM seems to be > present even with the changed CONFIG reg. The CPU starts up in expanded > multiplexed. The pink book states that the EPROM will always be switched ON > when the chip starts up in single-chip mode, but nothing is said about > expanded mux mode. Has anyone tried this before, what should I do to get > rid of the EPROM in the memory map? > > Jaap.

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