Fez Panda 2 not recognized

Hi guys,
I am newbie on fez Panda and .net framework. I’ve stuck here for weeks and desperate for help.
I’m working on a school project and I have the board from my seniors. The board controls a few servo motors through serial communication. The servo motors are supplied with 9V using an external power.

The board initially worked well. I modified the code with a few parameters and deployed to the board. The servo could not be started.
I deployed the original code, it failed to start the servo.

The pins to the servos are soldered on another board, which is plugged to fez panda. The output voltage to the servo is 9V. And I did a quick check on my senior’s soldering, it should be ok.

Now deals with the fez panda.
I inserted a piece of code to blink a led on one of the I/Os and run the program. The led blinked, indicating the program is running inside.

But I’m not sure if the serial port is working, thus the servo fail to receive commands. How can I check?

Another possibility is the code. I just copied the entire project to another location and had modification there. There might be some references not included properly or ?
So I created a new project, copy and paste the original code one method by one, and include the references.

  1. But before testing this, I came across new problem.
    My win7 64 bit laptop cannot recognize the board.
    The device manager either not refreshing to show anything, pop up message of “cannot recognize”, or “NETMF debug interface” with a warning sign.
    the led sometimes lights up for a while, sometimes off, sometimes lights on.
    MFDeploy, updater, and FEZPanel cannot connect to panda.
    It gets hot after plugging in for a minute or so.

By searching on forum:
change cable, usb port, plug out other device: not work
I don’t have a powered usb hub right now.

re install the GHI package: not work

Update the firmware: how can I update the firmware when it’s not recognized by PC?

I just read a post on how win7 hibernate freeze panda if it is plugged in for long without program running. I did have it plugged in for a while and working on programming, then I found the led off and it gets really hot. If the fez panda is freeze, how can I solve it?

My friend suspect it is burnt. From your description I feel it should not be burned so easily.
On the other hand, as the servo power supply is much higher than fez panda, the large current may burn the board.
The weird response may come from my stupid mistake.

Really appreciated for your time on my long description!


Panda’s getting hot - is not a good sign. However it is possible that it can be fixed.
Checking voltages coming out of regulators would be my first step.

@ Architect -

Thanks for the reply
You mean check the voltage of I/o or?

My urgent problem is not recognized by pc?
Is it possible that the board is burnt?

Highly likely you have fried the chip.

It is likely you’ve put 9v into the USBizi chip and it will no longer work.

@ Architect was asking you to check the voltages on the output side of the voltage regulators. You will need to look at the schematics and then touch your multimeter to GND and the outputs of the VREGs.

Thanks Brett! :slight_smile: I am not sure if GHI still sells them, but you can replace USBizi chip. Some people did that in the past.

The chips are available of course but for $30 I would just buy a domino http://www.ghielectronics.com/catalog/product/133 or a panda for $40

@ Gus -
Thanks for the information.
Because I am doing a school project and not sure if changing the board will work. I wonder what are the advantages of the alternatives?

The difference between Panda and Domino is the number of IO pins you have available to you - if you can get by with just the “arduino” compatible pins plus UEXT, you will be able to get by with Domino. There is basically no code changes, you may have to just re-map pins. If you’re using Fez Touch though, get a Panda II

@ Brett - @ Architect
Thanks for the advice.
I’m very new to the board and plz bear with me if I ask stupid questions. I’d have a clear troubleshooting plan so that I can have more solutions next week.
Can I know what VREG is? Do you mean test the output of the board or the USBizi chip?

VREG=Voltage REGulator

Measure the output voltages of the VREGs on the board. On a Panda II they are the three-pin (plus big metal tab) chips marked IC3 and IC4. Mine have “AMS1117” numbering, one is 5.0v and one is 3.3v, and the outputs of those should be regulated to those values.

But I still think your USBizi (main processor) chip has been damaged by connecting the high-voltage supply incorrectly somewhere sometime. I think the only resurrection of that would be to replace the chip, but as Gus says you may as well replace the board, they’re virtually the same price (and it’s a smart move, in case you’ve damaged something else too)

@ Brett - @ Gus
Thanks for the instruction
The voltage regulator IC 3 gives 0V output. IC4 (which has 5V and gives 3.3 V output, and supplied from USB) has a 4.3 output. I guess that’s why when first connected, the led blinks; after a while USBizi gets very hot and led off. I connect a 10uf capacitor to it, and a 3.1V output is generated. Seems the capacitor is penetrated.
But IC3 still do not have output. PC cannot recognize board either.
btw, I supplied a 9V to the secondary pin Vin, and a 3.3 V is generated from the output.

Anyway, the not recognizable device is meaningless to deploy any program.

Waiting for further suggestions.

Your device is cactus, I suggest you order a new one or a USBizi100 chip - in fact, if you order both you will have a brand new device to keep your project moving with, and a chip to give you some soldering practice

If you really want to keep diagnosing, then you need to give us more info like @ Andre asks. Do all the same tests and report back on the results more accurately.

In the case of inputting a 9v source into VIN, I expect you to get 5v out of the IC3, and then 3v3 out of IC4. In the case of USB only power, I expect IC3 won’t be operating and IC4 should still output 3v3.

it was quite weird that when I powered through usb yesterday, I have 4.3 V output from IC4, and 3.3 when added a 10uf voltage.
I tested today:
usb power: IC 3 not operating, IC4 3.3 V
9V Vin: IC 3 4.9V, IC4 3.3V
which is working.

When I first plug into USB, led blinks
after a while, it stops blinking and lights on
after a while, the light gets off.
Does that indicate anything?

Probably that your device is cactus? :slight_smile:

It could be power - the VREGs might change voltage profile over time as heat builds up for instance. It could be a capacitor not behaving. It could be the chip has failed. It could be code ! Which LED were you talking about, the POWER LED or the user LED?

Where do you want to stop troubleshooting ?

@ Brett - @ andre.m
Yes I think it’s confirmed damaged.
I ordered a replacement but it takes time to deliver.
Thank you for your help~I did learn debugging skills and knowledge from your guys.