7e usb connector wiring?

guys I was very generously given a slightly injured 7e for the price of shipping from a fellow rcgroups member, he had removed the mini usb connector with the intention of moving it to a more convenient location for when using a sim, but for whatever reason he abandoned the plan and I now have the tx.

anyway in removing the mini usb header he has pulled off 2 of the traces, one is vdd and the other is id, but looking at the board these aren't hooked up to anything anyway. the three remaining traces, data+, data- and gnd are all still intact, so in an attempt to use this tx while I await my 4in1's arrival today I installed 3 rf modules and hooked up a 3 pin connector to the usb traces. but when i went to try and edit the hardware.ini, and then when that didn't work I tried to update the firmware but unfortunately something isn't working :/

the 7e is not prooerly recognised no matter what way I connect it, be it programming mode, or usb drive mode, or usb joystick/controller mode. windows detects the device connecting but always complains that the device malfunctioned and isn't recognised, I tried putting it in program mode and then manually installed the dfu driver and once complete the device properties states 'device failed to start'. there is good connectivity between the relevant wires I added and the mcu, and also gnd, and the tx works properly otherwise, but without access to hardware.ini I can't enable the modules and having no programming mode isn't much use either lol

any idea what could be wrong? any suggestions on what to try to fix this? surely the usb should work with just the three connections? as the missing two don't look like they were connected to anything? you can see the usb wiring i added in this pic

I'm not to sure about usb, but on the connector end did you connect the shield/case to ground also? I think it needs to be hooked up.

You probably tried, but since that's a likely cause for the error you see.. did you swap the data pins to make sure they weren't mixed up?

I just used a 3pin header on the wires so there is no shield, I do have some mini usb headers coming but it's been great flying weather so I got impatient lol

yeah I tried swapping the data pins round and it makes no difference to the problem unfortunately.

this makes no sense to me at all, as it should work ok the way it's wired

I'd try wiring up the 5V line as well, maybe it switches something when USB is plugged in.
Also, what is that small component on the data lines? Maybe that is damaged.

the thing is there is nowhere to hook up the 5v line as the trace has been pulled, but the trace didn't connect to anything anyway. I have no idea what that component is, I've never seen one like it before and I don't recognise the symbol that's screenprinted underneath it. it may just be a jumper as it jumps both data lines over a gnd line, and as there is good connectivity between my added pins and the mcu I presume it's still doing it's job.

I seem to remember that usb2 sets the device data speed by tying one of the data lines to the +5v line through a resistor, data+ for high speed, data- for low, I wonder if that resistor was in the mini b connector I cut off? I always presumed they would be in the usb device? but there are no resistors between the data pins and the mcu?

I'll look more into this tonight when I get home

I was looking at that thing just yesterday. It appears to be some type of inductor but I don't understand what it's for or what it does.

What's the screen printing look like under it?


Edit: do usb data lines need to be impedance matched [to eachother]? Maybe that's what it's doing... definitely some sort of inductor, you can see the wires wrapped around it inside.

i got a look of it under my loupe glasses and you can indeed see about 4 winds of wire round it but looking around at stm32 schematics the usb pins only need a 22ohm resistor between the mcu and the usb header, but those are definitely not there on the 7e board.

the symbol is this


it's kinda ferrite inductor like, but the extra line underneath the coil symbol has me confused, also there is one of these symbols for each data line.

Pin 4 selects between Host and Device mode, but device mode is already set ("open") since you don't connect it.

One other odd thing is the resistor below that other part.. I didn't measure it, but as far as I can tell it connects the shielding to ground via a resistor.. I have no idea what the purpose of that is. But I'd suggest connecting USB shield to one of the shield pads just to test if that changes anything.
There's also an entire small circuit above that that also appears to be connected to the STM32 somehow, and to the USB plug/inductor. I can only imagine it's some sort of sensing/switching circuit.

Saw this on rcg: http://www.rcgroups.com/forums/showpost.php?p=34339267&postcount=2498 . Seems like only D+, D- and GND are needed so if all those signals have continuity to the processor it should be working.

Of course it's previous owner could have accidentally shorted the pins in an attempted repair and damaged those pins on the processor internally. You've gotten really good at the processor changes, perhaps another ultimate7e upgrade?

p.s. the symbol does look like an inductor indeed, probably an added filter for the differential signals. I am however curious about that transistor/capacitors/resistors group at 2 o'clock from the usb plug.

yeah i reckon that a damaged mcu must be the issue, and i hadn't planned on using this tx at all, i only added the 3 modules as they were sitting about and that there has been nice flying weather, and i can't fly much as my ult7e is still waiting for pots and the 4in1 to arrive. i'll try this tx again when the usb headers arrive, and if that doesn't work then i'll think about swapping out the mcu, as i suppose it wouldn't hurt to have a spare ult7e sitting around lol

i don't think that small array of components has anything to do with the usb, as it only hooks up to the usb connector shield through that resistor (marked 0, so maybe just a jumper?) and earth, here's a better pic of the area, the trace that goes under the inductor is jumped over by the 2 data lines.




i'll post back if i work anything out with this one

silpstream wrote: ... I am however curious about that transistor/capacitors/resistors group at 2 o'clock from the usb plug.

BAT-54 diodes [2 diodes with either anode or cathode common, depending on part] come in a SOT-23-3 package like that. Never tested but I'd always assumed that was a diode there, dont know why I thought that but I always have. Should be easy enough to test next time I have mine open.

just to close this thread out a new mcu fixed the issue completely, so it definitely looks like the previous owner caused some issues when attempting to relocate the usb port. so it's confirmed usb only requires D+, D- and GND to operate properly