is the homework board different from the oem stamp??

NR1X

i have a homework board that works great but tried the oem basic stamp 2, hooked up to the same usb to serial converter and get "no stamp found".. i do get loopback and echo, but no stamp.. im thinking tha maybe the circuit on the homework board is different from the oem bs2.. or i might have ruined one of the transistors?? anyone else had this problem?? i have checked my soldering and all looks well, what should i check next?? thanks ahead of time..

Forrest

How are you powering the OEM BS2? If you're using a battery, then try a fresh one.

erco

Should function the same as far as the computer is concerned, unless there is a firmware difference. Did you just build the OEM board? Has it ever worked? If not, suspect your soldering. Try a regular serial cable/serial port hookup to verify, and as Forrest says, "Life is like a box of chocolates; always use a fresh battery!"

Remember, the homework board has those good/bad 220 ohm resistors in series with all the IO pins. Sometimes those affect your external electronics.

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·"If you build it, they will come."

NR1X

fresh battery and +5v at vdd on interpreter.. could resistor networks be reversed? both have dot alligned with square pad.. im at a loss.. i will recheck all solder joints, but really doubt this is the problem..

ok checked and rechecked solderjoints all seem ok.. went through with continuity tester and all lines seem to get where they need to.. guess all that is left is to get a straight thru serial cable and try that way.. must be that the oem circuit is a bit more restrictive than the circuit on the homework board... maybe my usb to serial cable is getting just barely rs232 compliant signal and oem circuit is lookin for a well within rs232 compliant signal?? stop me if this is a foolish idea...

Post Edited (kb1nrb) : 8/25/2008 8:31:41 PM GMT

sylvie369

I just connected up one of my OEM boards with the Parallax USB-to-Serial converter. It works just fine.

Are you using a different converter?

Edit: KC9KST here.

Post Edited (sylvie369) : 8/28/2008 3:28:52 AM GMT

Chris Savage

There is no difference between operation of the OEM BS2 and a Homework Board on the converter. If it works with one it should work with the other. It sounds like your built the OEM from a kit and it is entirely possible there is an issue somewhere. Ic could be soldering, a component in the wrong spot or something damaged during soldering (by heat or static). Check the 4 3-pin TO92 packages. There are two transistors that are the same, one different and the last package is not even a transistor. It is the brownout detector. These are the most common to be in the wrong place.

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Chris Savage
Parallax Engineering

NR1X

transistors and brnout detector in proper location.. must have cooked one during soldering.. any way to check em

erco

Allan:

Are the parts in proper location AND orientation? You can check the transistors with a multimeter, per http://www.electronics-radio.com/articles/test-methods/meters/multimeter-diode-transistor-test.php··The brown out detector is cheap to replace http://www.parallax.com/Store/Microcontrollers/BASICStampModules/tabid/134/List/1/ProductID/387/Default.aspx?txtSearch=oem+bs2&SortField=ProductName%2cProductName
and it looks like you can test it to see if it's pulling the reset line low (incorrectly). If it is fried and pulling reset low, you could remove it temporarily and pull reset high with a pullup resistor ~10K. Meanwhile, make sure your Vdd is getting everywhere it's supposed to all over the board, including the reset line.

Also check your resonator for proper orientation.

erco km6ds


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·"If you build it, they will come."

Post Edited (erco) : 8/27/2008 5:03:39 AM GMT

NR1X

thanks erco.. great link there.. i figured thats how i would go about testing the transistors.. not much time right now, but did check the reset pin.. shows+5v so assume that the reset supervisor is ok... will check out the txistors later.. as far as resonator, i think the ceramic resonator included in the kit is polarity insensitive.. i think.. Oh yeah, nice to have other hams around.. been running into alot of hams here.. 73's KB1NRB

NR1X

positive lead to collector and negitive lead to emiter... get 10k ohm reading.. this = cooked transistor... guess i better cool the iron down before the new ones come in.. actually i can probably find those at radio shack..

NR1X

ok im an idiot.. 10k resistance from resisistor network!!! tested transistors and all appear to be funtioning properly.. the diodes all work c to b and b to e with their respective polarity.. now im at a total loss... wish it was the transistors!!!

Chris Savage

Perhaps you could post a clear high resolution picture of the front and back of the board? Who knows...we may be able to see something from that. If not, you may be able to have our Tech Support Dept. check the module out for you.

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Chris Savage
Parallax Engineering

sam_sam_sam

kb1nrb

One thing you might check·is the·IC chips for bent pins this has happen to me more than once

The reason·I say this unless you take the chips back out you may not see it
if pin or pins are bent under the chip
Just an ·

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··Thanks for any··that you may have and all of your time finding them

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Sam

Post Edited (sam_sam_sam) : 8/29/2008 11:37:06 PM GMT