Subject:
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Problems with CONFIG of 68HC811E2
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Fri, 3 Apr 1998 18:08:01 GMT
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Original-From:
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E. Baeck <[erwin.baeck@]ihatespam[styria.com]>
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Viewed:
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1083 times
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Hi to all !
Here a very interesting info for all, they have problems with the CONFIG
of the "E2" (included myself). I found this at the motorola site
http://www.mcu.motsps.com/lit/faq/as-79.htm. Here the text:
AS-79
APPLICATION SNAPSHOT
PROBLEMS PROGRAMMING THE CONFIG REGISTER OF THE MC68HC811E2 ON THE
MC68HC11EVM
by Janet M. Snyder
INTRODUCTION
Special considerations exist when programming the CONFIG register of the
MC68HC811E2 on the MC68HC11EVM, hereafter referred to as the EVM board.
The procedure is the same as for any other part, and the programming
will take place, but it may not show up as having changed values.
GENERAL INFORMATION
The monitor of the EVM board must be revision 2.5 or later. Earlier
versions of the monitor kept the chip in bootstrap mode during a read of
the CONFIG register. Versions 2.5 and later solved this problem by
reading the CONFIG register in special test mode. For reference, the
currentrevision of the monitor in the EVM board is revision 3.0.
The problem manifested itself in these earlier versions of the monitor
by showing that the contents of the CONFIG register had not changed
after programming and performing a reset. It was due to the fact that in
bootstrap mode, the value of the MC68HC811E2 forces some bits to ones,
no matter what the value that was just programmed into it. It actually
programmed correctly, but there was no way to see it. The bits that are
forced to ones in bootstrap mode are 0 (EEON), 1 (nothing), and 4, 5, 6,
and 7 (EE0, EE1, EE2, and EE3 respectively). For applications where the
security option was not included, bit 3 would also always show as a one,
and if the COP timeout was not used, that bit (bit 2)would also be a
one. So, a common scenario of the failure would be an application where
the designer wished to reprogram the CONFIG register to turn off the
EEPROM, but no matter how many times the bit was attempted to be
programmed to a zero and then reset, the CONFIG register would always
read $FF.
Very interesting, isn't it ? The problem is, that the loaders check for
a CONFIG value of 0x0C and here it sees 0xFF in bootstrap mode ! Have
anybody a solution for this problem ?
Greetings to all from Austria
Erwin
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