Drivers installed but 'could not find USB device' error

[rperkins]

Hi,

There is an issue with the betemcu.cn USBASP as sold on http://9xrprogrammer.com, Ebay, and elsewhere. The betemcu.cn USBASP is the primary USBASP hardware available any more since HK apparently quit selling USBASP. Hopefully this will keep people from pulling their hair out reinstalling drivers or having the appearance of intermittent operation of their USBASP. luckily there is a workaround.

This issue mainly revolves around targets that have a backlit LCD or other circuitrys that initially have a very low resistance when powered up. Examples of this are the Turnigy 9XR and the HK KKmulitcopter control board that has an LCD. The MCU of the USBASP is being driven into brownout during the powering up of these targets.

1. Programmers involved - Betemcu programmers sold from March of 2013 till present ( September 2013). The manufacturer has been notified and is reverting to the working configuration. Only the programmers with a 3.3V/5V option are affected. Unfortunately these are the most popular models. The PCB is black. If you have a green PCB , you are not affected.
2. Issue - Avrdude reports 'avrdude: error: could not find USB device "USBasp" with vid=0x16c0 pid=0x5dc' even though the drivers are properly installed.
3. Cause - Manufacturer switched from using a '0' ohm jumper to a '2.0' or '2.4' ohm resistor as a jumper on the 3.3/5V option to power the target. During power up of a target with a very low initial resistance the majority of the voltage supplied by the computers USB port is being dropped across this resistor, causing the MCU to go into brownout.
4. Workaround - Plug the target (9xr/kkboard.etc) into the USBASP before plugging the USBASP into the computer

Long term fix for Units in the field if you dont want to be bothered with the order in which the devices are plugged in. Short out the 2.0 or 2.4 ohm SMD resistor that is being used as a jumper for the 3.3/5V target power selection. It is marked as R7 on the 2011 version. The 2013 version does not have a reference designation. The component in question will be marked 2R0 or 2R4 . You can run a line of solder right along side the resistor.

A schematic and pcb layout of both revisions of the PCB are here. The resistor is marked as '0' ohms in the schematic although that isnt true for the later versions of these PCB's
http://openrcforums.com/forum/viewtopic ... 109&t=3233

Why did it happen ? When questioned, the manufacturer made comments about 'additional protection ' for laptops USB power supplies. Upon further questioning and discussion the manufacturer agreed to remedy the issue. He has followed through in the past and I have confidence he will on this issue also.

Pictures of the component location, more details of that particular part of the circuitry, oscilloscope screenshots of the voltage drop at the MCU, are all available if requested. I just wanted to get this out now. I've only had a couple returns over this and now that I know what is going on it is easy to give out the workaround. I believe a portion of the people who 'just cant get the driver installed' or ' the driver was installed yesterday , but now its gone' were being bitten by this issue.

After installing drivers this is how I recommend the driver installation to be tested

1. Do not plug the target ( kkboard ) into the usbasp. plug the usbasp into the computer. Run a firmware read ( or flash ) command. Of course it will fail because the target isnt even hooked up. How did it fail ?
A. 'Device not found' error means the drivers arent installed . Install drivers.
B. 'Target not found' means that the drivers are good and you should proceed to the next step

2. In order for the target not to pull the usbasp device down ( this sometimes happens on targets that have a backlight LCD), Plug the target (kkboard) into the usbasp, THEN plug the usbasp into the computer.
3 run firmware read ( or flash ) command.

If you post back with more questions or concerns, include the command line portion of the error . it should say something like:
/blah/blah/blah/avrdude -C /blah/blah/avrdude.conf -c usbasp -p blah -U blah ... etc etc

[MikeB]

Bear in mind the protection may be necessary! I have had a situation when plugging in a USB device that took a lot of current my desktop computer powered off and didn't power back on. I took it apart to check for blown fuses and couldn't find anything, fortunately when I put it all back together and switched on it then did work. Probably a 'resettable' fuse opened and just needed time to cool down.

I'd rather have a bit of trouble with the USB device than a lot of trouble with the computer!

Mike.

[rperkins]

Thanks for the response. The device already has a 500ma resetable fuse. If you get a chance, take a look at the schematic. A link is in the first post. I'd be curious what you thought after reviewing the schematic.

[Budge]

Thanks for the info. I also had problems with non-lcd items like ESCs. The workaround for my ESCs and my KK2.0 were to power those devices separately. Worked great.

[rperkins]

Hi
Thanks for the response. In my testing powering the devices separately worked also. While trying to troubleshoot this issue with someone via email , I suggested self powering and it didnt work for them. Maybe a combination of things were going on with them.

Regarding ESC's, yes they should always be self powered. The main players recommend a current limited power supply. If you dont have a current limited power supply a couple of batteries in series or a 12v lightbulb in series with your lipo will work. When I say main players I mean Simonk via LazyZero.
( When I went to find this thread I now realize you already know this )
http://www.rcgroups.com/forums/showpost ... tcount=748
http://wiki.openpilot.org/display/Doc/F ... efirsttime

I do wish the betemcu.cn USBASP had a way to remove power to the target. Some USBASP have this option. I ended up cutting a trace to make that happen. Then I soldered across the cut when my testing was done.