trouble with USB connectivity

kamrans

Hello,

I'm trying to build a device that I read about in the last issue of MAKE magazine. It is called the Pixelmusic 3000 and it was designed by Uncommon Products. It utilizes the P8X32A-D40 chip.

Here are the online instructions for it's construction: makezine.com/14/pixelmusic/

I completely built the breadboard, but the parallax software was not able to find the propeller chip once everything was assembled. I then found a very simple schematic for testing the chip in the propeller manual so i built that. I have attached a photo of my breadboard as it is now along with the schematic. I even purchased a brand new D40 chip and tried that incase I somehow fried the old one. However, the new one is still not able to be recognized.

The light on the prop plug blinks briefly when i tell the program to search for any attached devices. however, It still cannot find anything. does anyone have any ideas?

I really appreciate any help anyone can offer.

Thanks!

ImmNek

Hi

1. Check your connections to the RST (pin 11), RX (pin 30) and TX (pin 31) from the Propeller Plug.
2. Connet all VDD pins (pin 12 and pin 32) to 3.3V and all VSS pins (pin 9 and pin 29) to GND.
3. To test only you chip and your connections, I suggest to leave the EEPROM and the crystal. You can connect it again, if the other circuit works.

Hope this will be helpful.

Immanuel

kamrans

Thanks Immanuel. I really appreciate your help. However, I stripped it down and tested those connections and I still get the "No propeller chip found" error...

I noticed that the voltage regulator gets very hot though. Is this normal? Also, the instructions called for a 6V power supply and a 3.3 V voltage regulator. However, I accidentally plugged in the power without the regulator in place. Would it be possible for this to fry or damage the chip?


Thanks again...

BradC

kamrans said...
Also, the instructions called for a 6V power supply and a 3.3 V voltage regulator. However, I accidentally plugged in the power without the regulator in place. Would it be possible for this to fry or damage the chip?

Not an unlikely outcome. You may well have damaged the Propeller.

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Pull my finger!

Cluso99

You say the regulator was not plugged in - do you mean you applied power to the propeller, or just the regulator was missing and therefore no power went to the propeller?
If the regulator was just missing then you should have not done any damage. If you applied it to the propeller then likely you have a decoration.

You may need a 100uF capacitor on the input to the regulator. The regulator should not get hot for that little current. Can you check the voltage out from the power pack? If it is a hefty power pack you may be getting a lot more than 6V out, which would then explain the regulator getting hot.

ImmNek

Yes, this could be possible.

Check the output voltage on our voltage regulater. If the output voltage is significant under 3.3V (1V or something like this or lower) and your regulater get very hot, then the propeller or the regulator is damaged (if all connections are correct and you do not have a short circuit).

Please measure the current consumtion of your circuit and tell me your measurement.

kamrans

So, I did some voltage tests and arrived at some strange results. The power adapter itself puts out 9V. So basicially the chip got 9V when i plugged it in without the regulator.

When i test it with the regulator in line, i get a reading of 3.7V anywhere in the line, even if i test the base of the adapter before the regulator. However, When i plug it all into the circuit, i read about 1.4v from any point in the circuit, even at the base of the adapter before it goes through the voltage regulator. When i read the legs of the chip itself, i get a reading of .40V.

The regulator gets extremely hot and It smells like it's burning when it is not plugged into anything. However, after it's been plugged into the circuit for a while, it cools down. Is this normal? What could be going on?


Thanks again for all your help. Sorry I'm so inexperienced at this stuff..

Mike Green

9V applied to the Propeller's power supply pins will destroy it. It may have damaged any of the other parts of the circuit as well (like the PropPlug or EEPROM).

It sounds like you need to start over again.

In terms of the regulator getting hot, that means that there is a lot of power converted into heat. Using a 9V adapter means that 6V at whatever current is being drawn has to be dissipated as heat. The Propeller likely was damaged in such a way that it represents a short circuit for the regulator. When it gets too hot and too much current is being drawn, it shuts itself down. It doesn't make sense that the regulator would remain cooled down after overheating, but it's hard to tell how things will behave when they've been damaged.

Mike Green

Once you fix things up again, make sure you have the proper USB driver installed. The default Windows driver for the FTDI chip used in the PropPlug won't work properly. You need the one from Parallax or FTDI.

Forrest

You should revisit the data sheet for your 3.3V voltage regulator and make sure you're using the correct capacitors. Most fixed voltage regulators need capacitors on the input AND output sides of the regulator. Also it's common to place small ceramic bypass capacitors (around 0.1 uF) across the Vdd/Vss connections close to each IC (Propeller, EEPROM, etc).

Steel

kamrans said...
When i test it with the regulator in line, i get a reading of 3.7V anywhere in the line, even if i test the base of the adapter before the regulator. However, When i plug it all into the circuit, i read about 1.4v from any point in the circuit, even at the base of the adapter before it goes through the voltage regulator. When i read the legs of the chip itself, i get a reading of .40V.

The regulator gets extremely hot and It smells like it's burning when it is not plugged into anything. However, after it's been plugged into the circuit for a while, it cools down. Is this normal? What could be going on?

This is a good indicator that you fried your propeller.· When you applied the high voltage, it burned up the chip creating several shorts on the chip itself.· These micro-shorts are the cause of your strange readings.

The reason why you are reading 1.4V/.4V is because of those shorts/damage that were created. There is now more current running·through the damaged propeller than the voltage regulator can provide.··This results in the voltage regulator providing much lower voltage as the current gets much higher.· Your Voltage regulator is saying, "Captain!· We can't handle any more power!", and the captain is saying "MORE MORE MORE MORE!", so the voltage regulator is making power adjustments to match the circuit's current requirements.

This is why it the voltage regulator is heating up.· Im sure that if you put an ammeter in your circuit, it would read about 1.5A.· If you do this too much, you will also damage the voltage regulator.


Do not connect anything else to the circuit and replace the prop AND the Voltage regulator before any other damage occurs.·

kamrans

Thanks very much for the information, Steel. This definately makes sense. I initially plugged in the completed breadboard without the regulator. Is it likely that I need to replace every chip that was plugged in? Would the current stop at the propeller or continue through everything and burn them all out?

I've attached a diagram of the breadboard, as well as a list of the parts. To make sure, Should I just buy alll the parts again? Like even the resistors and capacitors?

I never thought this project would be so expensive, but I guess it's my fault that it is...

Thanks again for all your help everyone.



Post Edited (kamrans) : 11/19/2008 11:25:39 PM GMT

sosaraujo

First you should build, for example, this power supply (I still didnt build). Power On and check signals before connect the next block.
Step by step, stage by stage, power on then power off, you should be able to connect each stage.
Check the propeller clip, first alone.

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Adrian Sosa Araujo.- San Luis, ARG - Time Zone (GMT -3)
El planteo de un problema es mas importante que su soluci