Subject:
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Debugging the memory circuit
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Newsgroups:
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lugnet.robotics.handyboard
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Date:
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Sun, 12 Sep 1999 21:15:13 GMT
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Original-From:
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Edward Delaney <EDWARDD@antispamEARLHAM.EDU>
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Viewed:
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586 times
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We've assembled two handy boards up to the point where we are testing
the downloader. In section 6.0.6 of the assembly guide, it says
"If the download process appears to go correctly, but then the Handy Board does not boot
with the Interactive C prompt, the memory circuit may not be working properly. Check
the orientations of chips U2 (the memory chip itself), U3 (the 74HC373 chip underneath
the memory), and U7 (the 74HC132 chip). If any of the chips is getting hot, it is probably
plugged in backward.
Check the soldering joints on the above mentioned chips, re-heating any that appear
suspect.
Finally, check continuity for each of the wires in the memory circuit (including address
lines, data lines, and select lines). Check that any adjacent wires are not shorted together."
Well, this is where we are. Both boards behave the same way and have been assembled
step by step by two groups of students. The download proceeds but the
boards won't boot. No chips are hot, everything is oriented correctly.
We've swapped chips with known good HB's to no avail.
Can someone help us by being more specific about testing the memory circuit?
There are several sets of conenctions that appear to be shorted together, but
the soldering looks very clean and there is no visible problem. Should there
in fact be continuity between any adjacent pins on these chips?
Many thanks!
Ed Delaney
-----------------------------------------------------------------
Ed Delaney edelaney@sctcorp.com (work)
or edwardd@earlham.edu (everthing else)
http://www.earlham.edu/~edwardd
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Message has 2 Replies:
 | | Re: Debugging the memory circuit
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| Hi Ed -- it *could* be that the desktop you're using isn't set up right to download to the HB's. do you have a known good HB you can use to test the download? alternately, there are some serial line debug instructions at (...) does not boot (...) (...) (25 years ago, 15-Sep-99, to lugnet.robotics.handyboard)
| | | Re: Debugging the memory circuit
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| Thanks Fred, Yes, we have several working ones that download and boot just fine. In fact we're going ahead with these, but it means we don't have 1 bot per student. Since the download appears to work, and just the boot does not, I'm stumped. It's (...) (25 years ago, 15-Sep-99, to lugnet.robotics.handyboard)
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