Difference between revisions of "Quiz Box from hell"
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[[category:projects done]] | [[category:projects done]] | ||
− | [[Image:Michai_031_schem_nok_1.jpg|thumb|'''Fig.1: wrong thinking.''' Original idea was to have serial interface to program simple tunes/delays for both contestants, using PNP/NPN transistors to control | + | [[Image:Michai_031_schem_nok_1.jpg|thumb|'''Fig.1: wrong thinking.''' Original idea was to have serial interface to program simple tunes/delays for both contestants, using PNP/NPN transistors to control carhorn-current, which failed even most basic smoketest.]] |
− | [[Image:Michai_031_schem_nok_2.jpg|thumb|'''Fig.2: still not ok.''' This time using a Darlington-setup to control current (thx Jan), but | + | [[Image:Michai_031_schem_nok_2.jpg|thumb|'''Fig.2: still not ok.''' This time using a Darlington-setup to control current (thx Jan), but car-horn was apparently very PSU-unfriendly.]] |
[[Image:Michai_031_first_board.jpg|thumb|'''Fig.3: little board ready for 1st real test.''' Of course, this test ''failed''. MCU kept on resetting; after much measuring and swearing I concluded either the PSU was not up for it, or fast switching caused some spike/dip on MCU's pins.]] | [[Image:Michai_031_first_board.jpg|thumb|'''Fig.3: little board ready for 1st real test.''' Of course, this test ''failed''. MCU kept on resetting; after much measuring and swearing I concluded either the PSU was not up for it, or fast switching caused some spike/dip on MCU's pins.]] | ||
[[Image:Michai_031_claxon.jpg|thumb|'''Fig.4: infernal sound-device.''' Almost got a heart-attack hearing it actually pulled 3A (as per spec); measurements even showed 4A. Oh dear Lord.]] | [[Image:Michai_031_claxon.jpg|thumb|'''Fig.4: infernal sound-device.''' Almost got a heart-attack hearing it actually pulled 3A (as per spec); measurements even showed 4A. Oh dear Lord.]] | ||
− | [[Image:Michai_031_claxon_power.png|thumb|'''Fig.5: | + | [[Image:Michai_031_claxon_power.png|thumb|'''Fig.5: car-horn and PC-PSU on scope.''' Blue line is voltage over 0.5 Ohm shunt in series with car-horn; yellow line is PSU-voltage. I am seriously guessing this PSU was not very happy about switching 4A on/off at 260Hz, because at some point it started behaving... funny. (Voltage would decrease a LOT when connecting car-horn as load; leaving PSU alone a bit seemed to make it 'ok' again.) So many, many things I still don't understand.]] |
[[Image:Michai_031_schem_ok.jpg|thumb|'''Fig.6: another schematic, ok this time.''' Actually, taking new buzzer made all the difference (of course); not that much was actually changed, schematic-wise.]] | [[Image:Michai_031_schem_ok.jpg|thumb|'''Fig.6: another schematic, ok this time.''' Actually, taking new buzzer made all the difference (of course); not that much was actually changed, schematic-wise.]] | ||
[[Image:Michai_031_innards.jpg|thumb|'''Fig.7: inside the box of mayhem.''' You can see 110mA 12VDC siren, and little board in front of it.]] | [[Image:Michai_031_innards.jpg|thumb|'''Fig.7: inside the box of mayhem.''' You can see 110mA 12VDC siren, and little board in front of it.]] | ||
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''ever'' look at it again :-) | ''ever'' look at it again :-) | ||
− | The main reason for even writing this is not | + | The main reason for even writing this is '''not''' having to buy |
anyone a 2010.04-beer for not doing wiki-update. | anyone a 2010.04-beer for not doing wiki-update. | ||
</blockquote> | </blockquote> |
Latest revision as of 14:10, 12 April 2010
Disclaimer
Yes. A lot of fsckups were made, a lot of things I still don't understand; in fact it's good to have this thing finished, now let's never ever look at it again :-)
The main reason for even writing this is not having to buy anyone a 2010.04-beer for not doing wiki-update.
But what is it?
Simple quiz-button thing:
- 2 buttons can be connected to 'box' through wries
- distinct sound is played for whichever player pushes the fastest
- short immune-/lock-period after someone pressed their button, to let quizmaster do his talk
Good, and how is this causing Trouble?
Things that went wrong, in this order (all PEBCAK-caused of course):
- ISP-programming wouldn't work for some reason, has never worked, eventually forgot about it and played disk jockey with MCU in/out of sockets
- STK500 began to act flakey, I think it's at the end of its prolonged life, may it rest in pieces
- burned resistor at base of driving transistor due to thinko
- made 2 PSU's instable (prolly) due to switching of high current, causing cursing, hair-pulling and in general dissatisfaction
- spontaneous buzzing sounds because of disabled brownout-detect on MCU
- spontaneous buzzing sounds because of fscked up adapter-connector
- spontaneous buzzing sounds because of short spikes/dips on button-wire
- code to program tunes, software UART, serial interface didn't fit into 1k (without wasting too much time)
Nice Things
But ok, in the end it works; software waits for button A/B being pressed for 25ms continuously, and if so, plays 'beeeep', or 'beep-beep' for A and B respectively.
Fitting all into the casing was also nice; some mild woodwork, drilling, working with Dremel(tm), glueing, and then some. It actually looks presentable; the on/off-button in particular is very nice to work with - I'll use it again some time.
Software is so extremely simple I CBA to put it somewhere; it's pretty obvious.
Also try having some fun -- Michai