Stuck - problems with breadboard clone

Forum 2005-2010 (read only) Hardware Troubleshooting
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I'm making my Arduino based on this tutorial and I can't get it to work.

Edit: To make a long story short, I can't get the power LED to light and the computer acts as if nothing is even plugged in, and I don't know what to do.

First I put it all together and when I plugged it in I would get a popup from Windows (XP) telling me there was a hardware malfunction (instead of the expected Found New Hardware wizard). I eventually found out that my SSOP to DIP breakout board for the FT232RL (the usb to serial chip) wasn't fully connected to the breadboard.

I trimmed the breakout's DIP leads (which I made out of salvaged jumper pins) and tested continuities with my multimeter until everything was connected properly. When I plugged it in again, I got the yellow power LED at the bottom left of the breadboard to light up, but I still didn't get the Found New Hardware wizard.

After some fiddling (adding and removing the exterior power components, etc.), returning the breadboard circuit to it's original state (the state in which I got the LED to light up), and plugging it back in, I couldn't get the LED to light anymore. I figured I might have shorted a circuit somewhere, so I unplugged the board, powered down and restarted my PC, and tested continuities.
I found that while everything else was fine (pin connections, the USB type B female connector, etc.), the yellow power LED was not connected to the power. After some more checking, I discovered that, while each blue ground rail on the breadboard was one continuous strip, each of the two red power strips were split in the middle, meaning that a component connected to power on one end of the strip would not be connected to the other end of the strip. I'm not sure how this is possible, as the LED lit up before. Maybe the rail broke while I was testing it (this doesn't seem likely though, as both power supply strips are split exactly in the middle)? Or perhaps the LED was getting power from some pin on the FT232RL chip somehow.

Anyway, I used some 22AWG wire to connect the power strips, and it still doesn't work. The LED doesn't light up, even though there is about 218 ohms of resistance between the long lead and the + on the USB connector and almost no resistance between the short lead and the - on the USB connector.

The computer doesn't do anything when I plug the board's USB cable in, and I can't detect anything happening on the board. I'm not experienced in circuit building, so I really have no idea what to do now.

I'm considering just buying the Diecimila (or perhaps some other non-breadboard clone) and moving on, but I already have all the components and everything so I think it would, perhaps, be giving up too close to success.

Any ideas?

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first thing to do is to check whether the FTDI chip is active, that is there should be a new com port visible in the device manager (if you use windoze). on linux there should be a note in /var/log/messages about loading an FTDI driver.

if that's not the case you won't be able to communicate with the atmel chip anyway.

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Thanks for the reply.

first thing to do is to check whether the FTDI chip is active, that is there should be a new com port visible in the device manager (if you use windoze).

I don't see any change under "Ports (COM & LPT)" in the Device Manager when I plug in the USB cable and click "Action"->"Scan for hardware changes".

if that's not the case you won't be able to communicate with the atmel chip anyway.

I figured as much, but I still don't know why it's not working or what to do to make it work. Is there perhaps some set of things I should check with my multimeter? I've never debugged a circuit before.

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hm, which FTDI board do you use ?
the prebuilt one from sparkfun with the mini-usb plug ?
this one is powered by the pc' s usb port and should immediately trigger the hardware wizard.

if you got the adapter pcb and solderer the ftdi chip to it, check for shorts/cold soldered joints. then just concentrate on getting the ftdi chip working without the rest of the arduino parts. measuring if the chip actually gets 5V from the pc when on your proto board is also a good thing.

5

hm, which FTDI board do you use ?
the prebuilt one from sparkfun with the mini-usb plug ?
this one is powered by the pc' s usb port and should immediately trigger the hardware wizard.

if you got the adapter pcb and solderer the ftdi chip to it, check for shorts/cold soldered joints. then just concentrate on getting the ftdi chip working without the rest of the arduino parts. measuring if the chip actually gets 5V from the pc when on your proto board is also a good thing.

I got the breakout (adapter) board (from SparkFun) and the separate chip and soldered them (with some difficulty, which may be the cause of my problems).

I found two anomalies when checking continuities and shorts with my multimeter (using the 2000k max ohmmeter selection, since it doesn't have a beeping continuity tester as far as I can tell).

First is that there is a short between pins 25 and 26. This is intentional; I accidentally lifted the pad on pin 26, and I figured that directly shorting them should be ok as they both go to ground anyway (as described in Step 3 here).

The second one is a bit more interesting. There seems to be a short between pins 17 and 18. When I test the resistance between the two pins, the meter shows around 400k Ohms (well, it shows around 400 on the 2000k range, which I think means 400k). Could this be an intentional connection inside the chip, or is it an unacceptable short that I must have made when soldering (and that I need to remove)? Or does this matter (with the high resistance and all)?