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Support Forum » Borked butterfly?

February 17, 2013
by richnerd
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The LED closest to the GND wire of the programming header of my butterfly comes on (photo below left) whenever I connect the battery to the breadboard at the voltage regulator (photo below right) almost as if there is a backwards flow of current.

LED at header battery_hookups

This happens regardless if the usb is connected or not. Also, avrdude is no longer able to upload.

Is my butterfly blown?

I have the USBNerdkit, with a serial to usb connector; the chip in the butterfly is a 74HCT14E.

Thanks for any wisdom.

February 18, 2013
by Rick_S
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I'll give it a try... The PCB you are calling a butterfly is your logic converter board to take the signal from the USB to Serial adapter (The blue USB device) and translate it to a signal your microcontroller understands. The LED's on that board are tied to the transmit/recieve lines of the micro-controller and would not necessarily indicate a bad board. You may have other problems causing this. Larger photo's showing all the connections would be helpful to more clearly see what is going on.

Rick

February 18, 2013
by richnerd
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@Rick_S Thanks for taking the time to respond.

I'm sorry the photos are not too great, but I'm even worse at photography than I am with wires and breadboard.

If you have downloaded the Nerdkits Guide pdf, the LED I'm talking about is the one on the right in the photo on page 35. It lights up and stays lit whenever I plug the programming header's four wires (black, red, yellow and green) into the breadboard (power negative, power positive, MCU pin 2 and MCU pin 3 respectively), and connect the battery at the voltage regulator (as is shown in the photo on page 34 of the guide, just above the one I was just referring to).

Previously, the LED's did as you say; they switched on and off during uploading. Now, avrdude won't upload and that one LED remains lit constantly when the battery is connected.

I am wondering if that means the chip on the PCB/butterfly got fried somehow.

February 18, 2013
by Ralphxyz
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What I now need is a way to send that over the serial port and have the LEDs display that,

But you said earlier:

This happens regardless if the usb is connected or not.

With the USB connected you are probable seeing the phampton voltage from the USB yellow wire, when the USB is connected. If you search the Nerdkits forum you will see lots of yellow wire discussions.

Doubtful that the lit led has anything to do with a good or bad mcu.

Ralph

February 18, 2013
by richnerd
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@Ralphxyz Thanks for the tip on the yellow wire. I will do some testing and see if that one is the offender.

BTW, I don't know where the first quote in your post ("What I now need is a way to send that over the serial port and have the LEDs display that") came from. It is definitely not from any of the other posts on this particular discussion.

Maybe you've got a phantom or two of your own, eh. ;-}

February 18, 2013
by Ralphxyz
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Wow that is strange. I "thought" I was quoting you.

I haven't the slightest idea where that came from except I copied pasted it from somewhere.

Sorry for the miss quote, Ralph

February 19, 2013
by Rick_S
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Ralph, I don't know that the serial adapter would exhibit the same symptoms of "phantom voltage" as the cables and USB/Serial adapters you've seen.

I do find it odd that the LED that is lit is the one for indicating received data to the MCU. This LED should only light when the PC is sending data. With it lighting without the USB connected it seems odd.

Does the LED also light without the blue USB to Serial adapter connected?

Does it light with only the RED and BLACK wires connected?

There is a remote possibility that the 74HTC14 got zapped. If that chip is not functioning properly, the signals won't reach your MCU for programming.

Have you double checked the bottom of the logic converter board to make sure there are no foreign objects stuck to it or bent pins/wires that could cause a short?

All in all, most people here don't have the programming adapter you and I have. The NK guys dropped it a few years ago for an all in one USB/Serial converter cable. Depending on your solder skills, you could replace the 74HCT14 on the board if you determine it to be bad, or purchase a new cable from the NK store.

Rick

February 19, 2013
by richnerd
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@Rick_S You're right, I put the DMM on the yellow wire and there is no voltage there.

The answer to your two questions:

"Does the LED also light without the blue USB to Serial adapter connected?" Yes

"Does it light with only the RED and BLACK wires connected?" Yes

I'm afraid it's probably time to stop over at the NK store and get the all-in-one cable. Well, newer is better, right?

Thanks for your help in any case.

February 19, 2013
by Ralphxyz
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I'm afraid it's probably time to stop over at the NK store and get the all-in-one cable. Well, newer is better, right?

Unless you are running Windows 8. The NK cable is no longer supported on Windows 8.

Ralph

February 19, 2013
by richnerd
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@Ralphxyz Thanks again for that tip. Maybe I'll hold off buying that new cable for awhile.

February 19, 2013
by richnerd
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@Rick_S Gold star for you today. I desoldered the chip on the programming header as you suggested and put in a new one. Everything is working again.

No star for me though, I cooked the board a few times and shattered the old chip trying to knock it out while the solder was molten.

Anyhow, now I can wait until cable/Win8 situation that Ralphxyz warned about gets resolved.

February 19, 2013
by Noter
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Next time snip the pins to remove the chip and then desolder remaining pins and clear holes one at a time. Makes it a lot easier.

The cable/Win8 situation isn't going to be resolved unless Nerdkits tosses all their old cables and buy a new batch with a current version of PL2303 chips embedded in them. I doubt Nerdkits will do that so just buy a usb cable from a different source and stay away from PL2303 types so you don't get one of the old ones. Ralph likes his FT232RL device, I think he got it from SparkFun.

February 19, 2013
by richnerd
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@Noter

Next time snip the pins to remove the chip and then desolder remaining pins and clear holes one at a time. Makes it a lot easier.

Dang! Where were you 3 hours ago? Sounds like a much better method than banging the board on the worktable. I hope I remember for next time.

Thanks for the tip on the cable as well. Though the replacement chip for my aged NK cable is pretty cheap (I got three for about $1.20) so I'm set for at least two more crises.

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