Coobro GEO and FTDI Friend

[sixjays1985]

I purchased the Coobro Geo and FTDI Friend.
Everything checks out on the Coobro Geo (the test LED blinks continuously when powered on) and now I want to load the firmware.
I plugged in the FTDI Friend and saw in the Device Manager that it registers the COM7 serial port so it looks good to go.
As soon as I plug the FTDI connector into the Coobro Geo, the serial port goes away.
I first tried this using Windows 7. When I lost the serial port, I saw conflicts on a couple of the USB controllers (which also shut down my wireless mouse). The only way to get the FTDI Friend serial port back was to unplug the Coobro and disable and enable the problem USB controllers.
I thought maybe this is a Windows 7 or laptop computer problem so I tried it on my desktop computer running Windows XP. I plugged in the FTDI Friend and saw the COM7 show up in the Device Manager. Again, as soon as I plugged it into the Coobro, the serial port went away. The only difference is that on the desktop, I don't get the USB controller conflicts.
When I unplug the FTDI Friend from the Coobro, my serial port COM7 shows up again in the Device Manager.
Any thoughts?
Thanks.

[tcooper]

Hello Sixjays, sorry to hear you are having trouble with your Coobro Geo. Thank you for the detailed description of your issue. It sounds to me like there may be a short circuit involving the FTDI connection on the Coobro Geo. First, I would look as closely and see if you have any solder bridges or any noticeable shorts. Also, some pictures would be helpful as well. I assume you have used the double sided tape to attach the battery holder? We really need to take a look underneath if we can.

I did a quick test with an FTDI Friend by short-circuiting the ground and VCC lines. This did cause the same symptoms as you are talking about below, so we at least have a place to start looking. Also, when you plug in the FTDI Friend to your Coobro Geo, does the FTDI chip get warm?

Let me know what you find.

-Tyler

[sixjays1985]

Thanks for the reply. I removed the battery holder from the board and did a detail cleaning and inspection and couldn't find anything obvious. This time I did notice a message pop up in the lower right corner on my Windows XP monitor (by the task bar) that leads me to think you might be on to something. It probably appeared before but I didn't catch it. The message reads:

Power Surge On Hub Port: A USB device has exceeded the power limits of its hub port. For assistance in solving this problem, click this message.

The message goes away too quickly to click on it but then I couldn't click anyway since my mouse gets disabled while the Coobro is plugged in.
While plugged in, the FTDI chip does not get warm. It stays cool.
I attached a set of images for more information:
FTDI connector.

DSCN0544.JPG (227.43 KiB) Viewed 916 times

Corner view of board by FTDI connector.

DSCN0545.JPG (230.23 KiB) Viewed 916 times

Underside of Coobro board. I can't find any soldering problems.

DSCN0577.JPG (671.32 KiB) Viewed 916 times

I'm not sure what to do next since I can't find any shorts.
Thanks.

[sixjays1985]

Thinking there had to be something wrong on the Coobro board, I got the schematic and started checking all connections from the FTDI connector. I removed the processor chip and the capacitor from pin 6. After checking every connection, I was convinced there was nothing wrong on the board but still, every time I plugged in the FTDI connector, I had the same problem. I then thought it had to be the 6" cable I had also purchased with the FTDI Friend. That's when I saw the problem. See the picture below:

IMG_0002.JPG (46.82 KiB) Viewed 898 times

As you can see the red and brown wires crossover each other so that the red wire hooked to Vcc on the FTDI side gets shorted to ground when plugged into the Coobro. I checked the picture of the cable on your website and saw that it should be a straight through connection. The problem is, I don't have the tool to remove the wires from the connector so I can switch them myself. Is there an easy way to do this? Otherwise, can I get it replaced? Also, do you know if the double sided foam adhesive tape is easy to find locally so I can reattach the battery pack?
Thanks.

[adafruit]

woah, we've never seen that before! you can use a toothpick or tweezer tips to lift up the black bit and pull out the two offending wires & swap them.

http://www.ladyada.net/learn/chumby/serial.html

[sixjays1985]

Thanks for the link!
I swapped the wires and downloaded the program and everything works now.
I'm sure I can find some foam tape somewhere close by to reattach the battery case.

[tcooper]

Great catch, Sixjays! I am not sure I would have caught that even by staring at that connector.

By the way, great soldering job on that Coobro Geo. Once I saw those pictures, I knew I wasn't going to find any solder bridges.

Enjoy your Coobro Geo, and let us know if you run into any other issues.

-Tyler

P.S., let me know if you need another foam tape. I would be more than happy to mail you one. Just PM me your address. Otherwise you can find small rolls of double sided foam tape at hobby shops, and often hardware stores for a couple dollars.