Objective Development Forums

Re: Help! Windows stopped device it reported a problem?

2009-11-06T04:32:27+02:00

Dang, you're right. the atmega8-16pu, at 16mhz, has an operational voltage range from 4.5-5.5 volts. No solution A i guess. That leaves pretty much the zener diodes. All right, so maybe a silly question, but if I have 3.6 volt zener diodes which claim to be such but regulate the voltage from 2.9 up to around 3.6 as i change voltage from 5 to around 12, what does this exactly mean. Defective zener diodes? Ive never heard of this behavior before and i used a 10k resistor in series with the diode and measured around the diode, not the resistor, so...

Statistics: Posted by Guest — Fri Nov 06, 2009 4:32 am

Re: Help! Windows stopped device it reported a problem?

2009-11-05T23:08:51+02:00

If it IS a mega8 (not mega8A or mega8L) then I don't think it's rated for < 4.5v operation. Check the datasheet for your device and make sure it can run at 16Mhz at ~3.6v.

Statistics: Posted by maxi — Thu Nov 05, 2009 11:08 pm

Re: Help! Windows stopped device it reported a problem?

2009-11-05T22:24:15+02:00

3.6V Z-diodes & 62Ohm. Make sure the diodes are rated 500mW or less.

Statistics: Posted by Grendel — Thu Nov 05, 2009 10:24 pm

Re: Help! Windows stopped device it reported a problem?

2009-11-05T20:01:15+02:00

Which hardware option do you use? Thing is, i've used this successfully a while back but i used the 3.6v zener diode but nwo i don't know where its gone....

Statistics: Posted by Guest — Thu Nov 05, 2009 8:01 pm

Re: Help! Windows stopped device it reported a problem?

2009-11-05T07:39:30+02:00

I've used V-USB w/ a mega8 16MHz just fine. Fuse bytes I use: high: 0xD9, low: 0x1F (w/o bootloader)

Statistics: Posted by Grendel — Thu Nov 05, 2009 7:39 am

Re: Help! Windows stopped device it reported a problem?

2009-11-05T06:01:22+02:00

Quick question: I have my setup on a perfboard. Should i be looking for any ground loops that might give interference? The microcontroller is being programmed fine but...

Statistics: Posted by Guest — Thu Nov 05, 2009 6:01 am

Re: Help! Windows stopped device it reported a problem?

2009-11-05T05:46:00+02:00

Alrigiht, still not working. I replaced resistors with 68 ohm and zener diodes witih regular diodes.
I searched a little and found a thread back from a few years ago in which the user also had troubles with 16mhz crystals.
viewtopic.php?f=8&t=1047&start=15
Has this been resolved? I guess my next step will be to try a 12 mhz crystal if i can get my hands on one and hook up the serial port for debugging. And try it on an older computer

Statistics: Posted by Guest — Thu Nov 05, 2009 5:46 am

Re: Help! Windows stopped device it reported a problem?

2009-10-31T04:09:58+02:00

So i tried Solution A, diode drop (and just, btw, im on windows 7)

3.68 volts on D- line, 0 on D+ line

.4 uF between V/gnd - when they are connected to rest of circuit, the voltmeter starts to flicker when measuring capacitance. Probably normal.. Also, they are a little ways from usb line as i am now hooking ancillary stuff to a breadboard.

67.4 ohm - D- line
100 ohm - D+ line
2 zener diodes wrong way to produce 1.4 volt drop

Also, the WATCH DOG TIMER ALWAYS ON fuse bit is set to no. (im reading off a fuse file in eclipse,
so i don't know if that corresponds to a 1 or 0). Don't know if that is important.

16 mhz crystal - when pulled out microcontroller cant be programmed. fuse bits are set correctly (CKOPT = yes, SUT_CKSEL (Select clock source) = ext crystal/resonator high freq, start up time 258 CK + 4ms)

So, in terms of hardware, the only thing that i can see that I don't have exactly like the configuration is that i used zener diodes to produce .7 volts and i have 2 different resistor values on the D+ and D- line (only things i had!) I'll have to wait like 2 days if i absolutely need to get the exact values and regular diodes.
Just wondering, on the software side, is code like the powerswitch still supposed to work with the newest v-usb or should i use the old one?

Any further debugging ideas? Im sure its something really obvious...

Statistics: Posted by Guest — Sat Oct 31, 2009 4:09 am

Re: Help! Windows stopped device it reported a problem?

2009-10-30T22:14:54+02:00

On line D+ and D- use 68~100 Ohm resistors! And zenner diodes must be plugged as shown at http://vusb.wikidot.com/hardware Solution B!
If you want to use 2 diodes to drop out 1.4V, you must use http://vusb.wikidot.com/hardware Solution A the second shematic. And one more: make shure, that fuses programmed OK! Try?

Statistics: Posted by Guest — Fri Oct 30, 2009 10:14 pm

Re: Help! Windows stopped device it reported a problem?

2009-10-30T21:21:43+02:00

Gorm wrote:On the d+ line i have a zener diode in series with another zener diode in opposite direction (i.e. clipper diode configuration) to produce a 2.9+.7 voltage drop.

I suggest you try one of the setups recommended in the wiki http://vusb.wikidot.com/hardware You may be getting the correct levels initially but both lines need to be to pulled in opposing directions to facillitate data transfer. Some systems I am finding are more forgiving than others.

Statistics: Posted by maxi — Fri Oct 30, 2009 9:21 pm