Objective Development Forums

Hi everyone.I am opening this topic as a guide, in order to help any beginners,like me,experimenting with V-USB and facing the "Unknown USB Device" problem.
First of all,I will introduce myself.I am Electronics and Computer Engineer studding at the Technical University of Crete,Greece.
As part of my studies I have to prepare and present a final project to receive my diploma.I am saying all that to explain that this is my point of view for all I am describing below,my believes and in order to help you understand the quality of my sayings.
I take no responsibility for any damage you cause to your hardware.

As part of my project is to build a usb interface between a Graphical User Interface and a Development board.I have to make them "talk" each other through the usb port.So,after googling I discovered metaboard : http://metalab.at/wiki/Metaboard
After constructing the pcb and assembled the parts, I tried to flash the ATMEGA168P-20PU I am using with various firmwares like USBasp, USBaspLoader, PowerSwitch, etc......
I always kept getting the message "Unknown USB Device",when I was plugging the usb cable.So after lots of search, I have to recommend to all of you that facing the same problem,these 4 solutions:

1)First of all, triple check your hardware.Check for any misplaced part or cold soldering,etc.....If possible check one by one the parts with a Multimeter and other equipment.

2)Try to add 2 zener diodes and 2 resistors as shown below:
http://tinypic.com/view.php?pic=11vlet1&s=5
This helps to keep the voltage,at the D+ and D- lines of the usb,at 3.6Volts.Note: R1 and R2 could be between 68 to 330 Ohms

3)Try to write the AVR fuses correct.See the values of the fuses at the project's manual you are building.
Hint:The values,usually, are also in the "MakeFile".

4)If the above do not work,change at your usbconfig.h the values:
#define USB_CFG_IOPORTNAME X
#define USB_CFG_DMINUS_BIT A
#define USB_CFG_DPLUS_BIT B
X= is the port of the AVR that the D+ and D- lines are connected
A= is the pin that D- line of the usb is connected
B= is the pin that D+ line of the usb is connected

If nothing of the above do not work,GOD helps you!!! (Try to call 555-paradise-1234....just joking).

That is all I know so far concerning this "Unknown USB Device" problem.
Please feel free to contact me for anything and PLEASE correct me if I am wrong.

A few more things I've found out through my experiences. Mostly, these are more for issues with connectivity where it only connects some of the time.

1) Decoupling Capacitors - put a 0.1 mF capacitor between Vcc and GND, right where it comes into the chip.

2) Pull reset HIGH. I found out that sometimes, I'd have issues with the reset pin being pulled low randomly by my ISP programmer (long cable), so to make sure that doesn't happen, throw a pull-up resistor between your reset pin and Vcc.

3) Make sure your HID descriptor is correct. Try replacing your descriptor with one from a proven-working example.

Hope these help someone!

For USBaspLoader, I am using ATMEGA8 with 16MHz crystal, 22p capacitor. 68 ohm with 3.6 zener diode, 1k ohm, 1M ohm resistors for D- & D+. I am getting "Unknown Device" always(and USB Device Not Recognized). The Vendor & device id, i am getting in PC is 00, 00. But, in code, everything is fine. I made the circuit exactly as Metaboard circuit.
I tried the circuit in Breadboard & it did not work. So i thought, it might have Electromagnetic interference & soldered in PCB. In PCB also, it did not work.
Please Help..

After long experimentation time I found out that the best solution is to apply a reduced supply voltage to the AVR.Use any of the following ways as described here http://vusb.wikidot.com/hardware .Personally I have used two diodes in series and usbasp worked like a charm!
Hope that's helpful!
chears

Greetings,

I have tried all suggestions to get my Metaboard to work with USBaspLoader to no avail. It works with an ATMega8 perfectly, but with the ATMega328p no dice. I've downloaded the firmware and used AVR Studio to compile with the suggestions made the 328p part won't work. I still get the "Unknown USB Device." I have used a breadboard and a nicely made two layer board and still no luck. I am able to burn any code into the 328p and make it work but I can not get the USBasploader to work.
Are there any other suggestions, besides going back to the ATMega8?

Hi RCamaran,
I am still out of luck with atmega8 usbasploader. can you help me?
Please mail me the Exact circuit diagram & hex files used..
My mail id is [ deleted ]

(My problem is i am getting USB device Not Recognised every time & shows as unknown device with uid, vid as 00. are you facing the same problem with 328?)
Thanks.

lxkarthi,

I followed the design of the Metaboard for my project. I deviated from the original hardware by using a 470 Kohm for the D+ pull down to ground and by using two diodes in series with the +5 Volts supply from the USB connector. The last change allowed my board to work with the ATMega328p part. I used the hex files provided by Christian (Thanks a million) for both, the ATMega8 and the 328p. I have successfully used the Arduino IDE with both boards and multiples PCs and Macs without any issues.
I should thank all the smart people in this forum for sharing their ideas and knowledge.
If you are still having problems, I could send you hex files, drawings and fuse settings as well.

Regards

RCamaran wrote:lxkarthi,

I followed the design of the Metaboard for my project. I deviated from the original hardware by using a 470 Kohm for the D+ pull down to ground and by using two diodes in series with the +5 Volts supply from the USB connector. The last change allowed my board to work with the ATMega328p part. I used the hex files provided by Christian (Thanks a million) for both, the ATMega8 and the 328p. I have successfully used the Arduino IDE with both boards and multiples PCs and Macs without any issues.
I should thank all the smart people in this forum for sharing their ideas and knowledge.
If you are still having problems, I could send you hex files, drawings and fuse settings as well.

Regards

Thanks a lot for helping me.
Please send me exact schematic you used and hex files, fuse settings. What crystal did you use?
send to [ deleted ] com
Again, Thanks a lot.

RCamaran wrote:lxkarthi,

I followed the design of the Metaboard for my project. I deviated from the original hardware by using a 470 Kohm for the D+ pull down to ground and by using two diodes in series with the +5 Volts supply from the USB connector. The last change allowed my board to work with the ATMega328p part. I used the hex files provided by Christian (Thanks a million) for both, the ATMega8 and the 328p. I have successfully used the Arduino IDE with both boards and multiples PCs and Macs without any issues.
I should thank all the smart people in this forum for sharing their ideas and knowledge.
If you are still having problems, I could send you hex files, drawings and fuse settings as well.

Regards

I could use all of this info as well. I am battling the same issues.
johnsonj at yahoo dawt com

Greetings,

I will email you both the drawing and the hex files I used. Please let me know if there is a way that I can post them in this forum, as I think that other interested users may benefit from them and I am not well versed in the use of forums.

Regards,

Mail me. I will upload the files in a file-sharing site and post the link here.
Thanks for helping.

please do send me arabindo045@gmail.com I am using ATMEGA8 with 16MHz crystal, 22p capacitor. 68 ohm with 3.6 zener diode, 1k ohm, 1M ohm resistors for D- & D+. I am getting "Unknown Device" always(and USB Device Not Recognized).