Zed is dead baby !
TE44
Posts: 42
I have managed to kill 2 40pin dil props in breadboard - seems strange - even though I had regulators & diodes in reverse across the supply & caps etc (all as recommended and more) they worked fine and programmed ok but when I removed the power and reapplied it the props were dead - each time though I had ascreen attached as per schematics (except for led's and associated resistors) - do the LED's in the schematic play some additional role in dissipating unwanted spikes ? - or is this just a coincidence. Removing power this way (same power supply) using the demo board does not cause any difficulty. Is there some additional 'soft start/stop' circuitry I have missed ? I find this strange as all good practice was followed with respect to power supply stage.
Has anyone else killed a prop for what is an unknown reason (at least unknown for the moment)?
Post Edited (TE44) : 1/24/2007 4:59:50 PM GMT
Has anyone else killed a prop for what is an unknown reason (at least unknown for the moment)?
Post Edited (TE44) : 1/24/2007 4:59:50 PM GMT
Comments
Can you post your schematic? This shouldn't happen. The LEDs are not necessary nor is there any start/stop circuitry required. I'm curious about the extra diodes and where they're connected.
I haven't tried Props in a breadboard other than once on a BS2p40 breadboard just to try it out and not killed one yet. It's kind-of winter here and there's lots of static discharging left and right. I might destroy one that way. I ruined a Palm once with static - oh that was sad.
I have had BS2,BS2P40,Javelin Stamps all on bread board before without any issue either.
I will post the schematic soon - must draw it up first.
Post Edited (bassmaster) : 1/24/2007 6:21:07 PM GMT
··············· All are fine -·they are dead - vdd @ 3.287v - scoped for spikes when pulling supply - nothing appreciable - VSS fine - I killed one for sure - tried a second one with·additional diodes in psu·and repeated power remove & apply after about 3 attempts I successfully (!!?) killed the second one. No loads on the·prop except·vga but that·was checked and triple checked. On my last one now (more·on the way - just in case·!!) but I have the demo board·to play with if I kill that in the meanwhile !
Looking at the·Prop 40 (dil model) I noticed parallax have not shown VSS connected to pin 29
or VDD to pin 32 - even though they are labelled - I have applied vss to pin29 and vdd to pin32 but I don't expect this to be an issue .....
·http://www.parallax.com/dl/docs/prod/prop/PropellerHardwareConnections.pdf
also see my supply schematic attached
before I decided to try the second one - I left it on overnight running loops and outputting to the screen - no problems - loading eeproms all fine - when the props died the eeprom was always ok and its off the same supply line ? All anti-static handling was also observed ....
The 3 (resistor oops typo) transistor serial programming circuit was also attached but this was also checked numerous times - and besides it programs the eeprom and prop just fine -·happened both times after power removal·/ power attach - which did it I can't be sure·- just sure it was dead when·I reattached the supply. Prop not hot ,supply good .Over kill with diodes on supply side no inductive loads or loads except·VGA·(checked).
Post Edited (TE44) : 1/24/2007 7:30:12 PM GMT
that it dies when you pull and reconnect the power. How are you pulling and reconnecting the power? Do you just pull
a single wire from the breadboard, or multiple wires? Or are you using a switch of some sort?
Is the bottom of the breadboard still insulated? What sort of work surface are you working on?
Killing a demo board is a pricey proposition! If these questions are too silly, I'm sorry; I don't mean to imply anything.
It's just the chips seem to be pretty sturdy in my experience, and killing more than one in the same setting really seems
to imply something's odd in that setting.
The demo board is fine - same power supply being used - no issues - proper work bench - the 'breadboard' is a plastic device and the bottom is insulated so that is not an issue. Pulling a supply connector - i.e both gnd and Vin pulled together.
It kind of has me baffled at this stage - if you notice the prop supply pdf - I went overboard on diodes just in case - before the second 'killing spree' i disconnected everything - rebuilt ,rechecked modified supply (more diodes) - left running overnight - fine - pulled and applied the supply connector a few times and hey presto !?
Bassmaster,
You got that one right ! I never managed to kill a stamp though.
Post Edited (bassmaster) : 1/24/2007 8:07:25 PM GMT
My theory is.... The TV killed them
I think the problem is/was in my TV, not the circuit, or Propeller attached to it. I never measured what was coming out of the TV's composite input with a multimeter, but I assume nothing should be emanating from that composite jack. Am I wrong?
▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Brian Meade
"They who dream by day are cognizant of many things which escape those who dream only by night" - Edgar Poe
That is interesting - I take it you used the 3 - 5v variant of the MAX232 ? Just wondering about the reset - did you have to use a transistor for that ?
················ Yeah I was wondeing if there was something similar happening - which is why I referenced the LED's in the initial post. Its bugging me a bit now !
·
There must be something other than the power supply involved.· If the crystal were broken, the Prop would still talk to·the Prop Tool·since that runs off the internal oscillator.· As was mentioned in another thread, the Prop is a pretty resilient chip.
I have a question about how you have the monitor connected. Are you connnecting all the VGA pins up the same as on the demo schematic? The reason I ask is that on your schematic for the power shows the +5V supply as 'not used' and it should go to pin 9 on the VGA connector.
Do you have everything wired up like the demo board or are you doing something else?
One way to troubleshoot this to see if your propellers are in fact truely dead is to get it back down to the most basic propeller circuit. That would just have the propeller, crystal, EEPROM, and your choice of programming adaper, Propclip, homebrew, etc. An easy way to do this (without messing with the rest of your circuit is to get a 40-pin DIP socket, plug the propeller into that, and then bend up all the leads that you are currently running to other devices like your VGA, etc. This will let you open those circuits and remove them as contributing to the problem. You may find that your propellers are fine and something else id causing the trouble.
I had a couple issues getting my propeller up and running (I built a demo board on a protoboard) but most of that was caused by assuming the reset (atn) for programming was like the stamps. I had used a MAX232 circuit. I found that the diode and feedback resistor that normally appear on a stamp circuit prevented the Propeller from being recognized.
Hopefully you'll get yours figured out as well.
Robert
http://www.parallax.com/dl/docs/prod/prop/SerialtoPropeller.pdf
Yeah - I have read that - crystal is out of the loop as - like you said you could still talk to the prop. if the crystal was iffy but I got no propellor found !
The 5v is not needed for the VGA - even though its stated - on the schematic - it works fine without it..
With/Without a 10uF cap at output stage it wouldn't be responsible for killing the prop - I have had larger caps at output stage also .. just placed a 100uf cap at output stage - no real difference in vdd - increased by .02v
That seems fine - because when I replaced the chip - it worked fine after - programmed and ran - also tried to swap back - no response - I am afraid they are indeed dead !
Just out of curiousity, was your PC still connected to your Prop via the three-transistor interface when you turned off the power? If so (and this is a very long shot), with the power disconnected and the PC connected, measure the voltage on Vdd. I ask because, looking at the schematic for the three-transistor circuit, there is at least one weak conduction path with the power off. I can't imagine it causing a problem, but it doesn't hurt to investigate...
-Phil
Thanks for the reply - but the pc was not connected ...
Well, it shouldn't, but that 10uF is there for regulator *stability*; without it the regulator *might*
be oscillating. If it is oscillating, it might be providing enough voltage to kill the prop.
(And your voltmeter is showing an average, so if it is oscillating your voltmeter won't show
that.)
And of course oscillations are more likely at load changes (when you plug in or remove the
power). This is one reason it's probably smarter to switch at the input to the regulator, rather
than the output of the regulator (i.e., pulling the wires from the breadboard).
Actually, is the power circuit on the breadboard itself or external?
-Phil
Post Edited (bassmaster) : 1/24/2007 9:23:39 PM GMT
2) Have parallax an approved max232 based serial programming circuit with reset ?
fyi - measured resistance between ·pin9 and pin29 shows 0.8ohms - so they are connected anyway
·······measured resistance between ·pin32 and pin12 shows 0.8ohms - also connected.. so I didn't need
······ to include these connections.... I did initially in case there was some other internal requirement.
·······That said·my resistance lead to lead on the meter was 0.1ohm and the prop connections measured
······· 0.8ohms - i know it is·negligible but not if there was any internal monitoring ·being taken from·these
······· extra·VDD and VSS pins - I would assume though ,if these were anything else·other than·extra VDD &
······· VSS pins - they would not be labelled thus. can this be clarified as to why they are not shown on the
···· · parallax schematic.·Are they just extra VSS , VDD connections ??
··Phil - your link answered the question - the propstick schematic does indeed show these pins connectted to VSS and VDD respectively - where as the link below does not -
http://www.parallax.com/dl/docs/prod/prop/PropellerHardwareConnections.pdf
Post Edited (TE44) : 1/24/2007 9:53:42 PM GMT
I understand your point -but by its nature if there was fluctuations there should not be any above its zener breach·therefore over voltage would not be an issue .Also you will notice that I scoped the lines and any undue fluctuations would have shown up there - also the fact that there is a cap at the output stage (although small) helps - in actual fact the spec sheet specifies an input capacitor of around 10uF and an output capacitor of 0.1uF - you will notice that the supply would be smooth from the fact that the 7805 has a large electrolytic and a 0.1uF secondary thus ensuring a smooth 5v supply line to 3.3v reg.
Post Edited (TE44) : 1/24/2007 9:50:09 PM GMT
Thanks for that ... I will have a go at that now ....