Author Topic: PCB "Unknown USB (Device Descriptor Request Failed)" Issue  (Read 2128 times)

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Offline sanlouie_7

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PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« on: Sun, 13 June 2021, 14:33:19 »
Hi all, new post following up an issue that I had a few days ago as something new has came up and I think this may have been the issue all along. When I plug in my cable into the connector of the PCB, Windows will make a noise that recognizes that a new device has been connected. However, Windows is unable to determine what the device is.

The PCB is an Octagon Ver2.0 and everything was working well a few days ago until I decided to flash it with QMK. I'm not really sure where I went wrong or why it was working for a few days before a column of keys stopped working, then the whole board altogether. I reinstalled QMK with updated drivers, but unfortunately QMK is still unable to recognize the device. I have also tried resetting the board and plugging it in while doing so. Still, no dice.

I looked up several solutions online, finding things such as flashing with 02D, Flip, and updating atmega32u4 drivers. Admittedly, I have no idea how any of these things work. All I really do know is that it still makes a noise when plugged in and no keys or LEDs response when plugged in!

I'm still willing to put in the time and effort into making this bad boy work but preferably with some direction since I'm sure I have been attempting to do so without any. Will reply ASAP to any responses, thanks!

Offline Findecanor

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #1 on: Sun, 13 June 2021, 15:48:19 »
It sounds to me as if flashing QMK to the ATmega32u4's flash memory could have failed.

With the ATmega32u4, the firmware will need to have started and enabled the USB port at its end for Windows to be able to detect the device at all. After that, one of the first things that Windows does when detecting a new USB device is to ask it for its Device Descriptor, and that should also have been handled by the firmware. Weird that it does the first step but not the second.

I don't know which USB diagnostics tools there are on Windows, but I would check if it identifies itself as anything if you would put it in bootloader mode.
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Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #2 on: Sun, 13 June 2021, 16:30:41 »
It sounds like the firmware is corrupted.
Where did you source it from?

From the readme for the Octagon in the TMK repo it seems like you need to hold down the top right key while plugging in the PCB to enter bootloader mode.
QMK toolbox should at least recognize it at that point and allow you to flash it with some new firmware.
Does that part at least work?

If QMK toolbox doesn't recognize it after holding in that key while plugging in the PCB it's likely the bootloader which is toast.
Hopefully not the case because you'll need an ISP programmer to flash a new bootloader and the firmware.

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #3 on: Sun, 13 June 2021, 17:20:25 »
It sounds like the firmware is corrupted.
Where did you source it from?

From the readme for the Octagon in the TMK repo it seems like you need to hold down the top right key while plugging in the PCB to enter bootloader mode.
QMK toolbox should at least recognize it at that point and allow you to flash it with some new firmware.
Does that part at least work?

If QMK toolbox doesn't recognize it after holding in that key while plugging in the PCB it's likely the bootloader which is toast.
Hopefully not the case because you'll need an ISP programmer to flash a new bootloader and the firmware.

Unfortunately, I believe that the FLIP (top-right) key isn't working. I have tried on several occasions to get QMK to recognize the device while holding the top-right key and nothing appears to happen.

I have a friend who is able to use (I think) Arduino as an ISP and is willing to help me, but he also did ask where was my firmware and I wasn't really sure what he was asking. What would be the firmware in this case?

Again, I'm really unfamiliar with this stuff and I would like to be able to present him with all the tools he would need to hopefully get the PCB running properly again. And it seems like maybe in this case that is burning a new bootloader?

Edit: I flashed the firmware using QMK Toolbox but somehow it stopped working altogether about a day later.
« Last Edit: Sun, 13 June 2021, 17:29:17 by sanlouie_7 »

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #4 on: Sun, 13 June 2021, 17:22:23 »
It sounds to me as if flashing QMK to the ATmega32u4's flash memory could have failed.

With the ATmega32u4, the firmware will need to have started and enabled the USB port at its end for Windows to be able to detect the device at all. After that, one of the first things that Windows does when detecting a new USB device is to ask it for its Device Descriptor, and that should also have been handled by the firmware. Weird that it does the first step but not the second.

I don't know which USB diagnostics tools there are on Windows, but I would check if it identifies itself as anything if you would put it in bootloader mode.

This is what I was thinking too since I think I am unable to get the PCB into bootloader mode. I would also be afraid that the bootloader is toasted as said by MajorKoos.

I can try to find additional solutions online and see if anything would be worth giving a shot. This helps point me in some sort of direction and it is well appreciated :)

Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #5 on: Sun, 13 June 2021, 18:14:40 »
Try plugging it in holding down ESC, and if that doesn't work try again with Tilde.
Doubtful it will work, but process of elimination and all that stuff...

FLIP is an application written by ATMEL for programming their microcontrollers.
You can use either FLIP or QMK toolbox to flash the firmware onto the PCB.

If the hotkey to enter the bootloader isn't working it's likely because the bootloader itself is corrupted.
The normal startup sequence should be:
1) load the bootloader
2) check of any keys are pressed to enter "bootloader mode" or do other stuff
3) pass control to the firmware and exit

If it's showing up as an unknown device in Windows #3 isn't happening for sure.
If holding down the top right key doesn't get you into bootloader mode #1 is likely not working either.

Could you upload a photo of the back of the PCB?
Sometimes there are jumpers which you can short to force the PCB to enter bootloader mode - that would be the acid test.
Flashing it with an ISP may turn out to be necessary, but we'll first need to figure out which bootloader to use along with firmware.

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #6 on: Sun, 13 June 2021, 18:48:48 »
Try plugging it in holding down ESC, and if that doesn't work try again with Tilde.
Doubtful it will work, but process of elimination and all that stuff...

FLIP is an application written by ATMEL for programming their microcontrollers.
You can use either FLIP or QMK toolbox to flash the firmware onto the PCB.

If the hotkey to enter the bootloader isn't working it's likely because the bootloader itself is corrupted.
The normal startup sequence should be:
1) load the bootloader
2) check of any keys are pressed to enter "bootloader mode" or do other stuff
3) pass control to the firmware and exit

If it's showing up as an unknown device in Windows #3 isn't happening for sure.
If holding down the top right key doesn't get you into bootloader mode #1 is likely not working either.

Could you upload a photo of the back of the PCB?
Sometimes there are jumpers which you can short to force the PCB to enter bootloader mode - that would be the acid test.
Flashing it with an ISP may turn out to be necessary, but we'll first need to figure out which bootloader to use along with firmware.

I've tried about all the combination of keys that I could to access bootloader without success. I have shorted the two pins that force the PCB to enter bootloader mode (as instructed by suicidal_orange) and it seems the pcb is not entering bootloader still. I have done it prior to and while plugging in the USB cable into the connector.

Here are the two images that I think would address what you were asking for. I have been looking into ISP programmers after reading a page from QMK and I need to purchase one, correct? No problem with purchases one if I can get this pcb working again. I just wanna make sure I get the right one (if there is a specific one to purchase).


Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #7 on: Sun, 13 June 2021, 19:53:59 »
Yup, sounds like the boot loader is indeed borked if the jumper doesn’t work.

This is the programmer I use:
https://www.sparkfun.com/products/9825

Most PCBs are designed to be flashed from the front. 
You can use some jumper wires to reverse the pin out to flash it from the back without needing to desolder the plate.
First flash a new boot loader with the programmer and then do the firmware.

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #8 on: Mon, 14 June 2021, 02:36:08 »
Yup, sounds like the boot loader is indeed borked if the jumper doesn’t work.

This is the programmer I use:
https://www.sparkfun.com/products/9825

Most PCBs are designed to be flashed from the front. 
You can use some jumper wires to reverse the pin out to flash it from the back without needing to desolder the plate.
First flash a new boot loader with the programmer and then do the firmware.


Just purchased the ISP programmer that you linked and some jumper cables from Amazon. Is there anything else I would need? I have a hard time understanding how the PCB and the ISP programmer will essentially connect.

Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #9 on: Mon, 14 June 2021, 12:26:38 »
I just spent a couple of minutes looking at the PCB image - I don't see an ISP header anywhere on it for you to connect the programmer to.
I'd expect to see something looking like this:
270547-0

If there isn't a header for the programmer you have limited options.

You can connect directly to the microcontroller and program it like that, but it's going to be difficult because those points are very small.
Not impossible, but very finicky.

Or you could try find a compatible PCB. 
One of my mates got a KBD75 PCB and a USB breakout board from adafruit to mod his LZ CLSm which also has the USB in the middle.

Hookup guide for the programmer:
https://learn.sparkfun.com/tutorials/pocket-avr-programmer-hookup-guide/all#board-overview

Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #10 on: Tue, 15 June 2021, 03:19:18 »
The PCB uses IO expanders for the switch matrix, they probably use these pins and have larger targets to connect a flasher to.  I'll have a look in the firmware and try to work out what goes where, then where where is physically (which is fun as the designer likes vias with no clue which direction the frace continues on the other side)

Edit:  Looked, firmware is as old school as the board so not human readable.  Can you take a closeup pic of the area around the controller and confirm which corner the dot is, if it's not obvious in the pic?  Have to play 'follow the trace' and I'm already lost by R35!
« Last Edit: Tue, 15 June 2021, 03:43:46 by suicidal_orange »
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Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #11 on: Tue, 15 June 2021, 09:00:46 »
And a photo of the front side of the board too if you could...

Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #12 on: Tue, 15 June 2021, 11:09:11 »
There's a pic of the front in the other thread, it's an interesting design to say the least!
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #13 on: Tue, 15 June 2021, 14:15:58 »
The PCB uses IO expanders for the switch matrix, they probably use these pins and have larger targets to connect a flasher to.  I'll have a look in the firmware and try to work out what goes where, then where where is physically (which is fun as the designer likes vias with no clue which direction the frace continues on the other side)

Edit:  Looked, firmware is as old school as the board so not human readable.  Can you take a closeup pic of the area around the controller and confirm which corner the dot is, if it's not obvious in the pic?  Have to play 'follow the trace' and I'm already lost by R35!

Here is a picture of the area surrounding the microcontroller. Hopefully this is what you asked for.



Also if it's hard to see, the it is in the bottom corner in its current orientation.

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #14 on: Tue, 15 June 2021, 14:17:22 »
And a photo of the front side of the board too if you could...

I know it's already on the other thread, but just wanted to reupload just in case!


Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #15 on: Wed, 16 June 2021, 04:38:06 »
Had a look at this, as I see it these are the traces for the pins you want.  Cyan (SCK) is attached to the top of R105 (or 106?) Magenta (MISO) to the left of R53 and Green (MOSI) goes a long way but doesn't seem to be connected to anything - can I get a closeup of the right side of the front around the green dot?

Workings for anyone who can check I'm not doing something stupid (I don't want to kill a classic board!)

270617-0  270619-1
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #16 on: Wed, 16 June 2021, 12:59:45 »
Had a look at this, as I see it these are the traces for the pins you want.  Cyan (SCK) is attached to the top of R105 (or 106?) Magenta (MISO) to the left of R53 and Green (MOSI) goes a long way but doesn't seem to be connected to anything - can I get a closeup of the right side of the front around the green dot?

Workings for anyone who can check I'm not doing something stupid (I don't want to kill a classic board!)

(Attachment Link)   (Attachment Link)

Gotcha, I think I'm seeing what you're saying. And would 5V, RST, and GND have to go anywhere as well? I apologize as I have little knowledge when it comes to wiring.

Also, here are the pictures that you asked for. I hope that I took these correctly. Let me know if you need any additional information.

I've currently been reading on ISP Flashing on the QMK website and it seems that QMK Toolbox can take care of the burning of the bootloader?


Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #17 on: Wed, 16 June 2021, 15:13:07 »
Had a look at this, as I see it these are the traces for the pins you want.  Cyan (SCK) is attached to the top of R105 (or 106?) Magenta (MISO) to the left of R53 and Green (MOSI) goes a long way but doesn't seem to be connected to anything - can I get a closeup of the right side of the front around the green dot?

We're trying to trace these pins?
9 (SCK), 10 (MOSI), 11 (MISO), 13 (RST)
And then something like 14 (5v VCC) & 15 (GND)

Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #18 on: Wed, 16 June 2021, 16:47:33 »
Had a look at this, as I see it these are the traces for the pins you want.  Cyan (SCK) is attached to the top of R105 (or 106?) Magenta (MISO) to the left of R53 and Green (MOSI) goes a long way but doesn't seem to be connected to anything - can I get a closeup of the right side of the front around the green dot?

We're trying to trace these pins?
9 (SCK), 10 (MOSI), 11 (MISO), 13 (RST)
And then something like 14 (5v VCC) & 15 (GND)

Yup, I added coloured dots on the vias on both sides and only lines on traces where required (green).  5v and GND probably go to something LED related, I didn't think to do them (damn stupid disease!)
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #19 on: Wed, 16 June 2021, 19:03:14 »
Had a look at this, as I see it these are the traces for the pins you want.  Cyan (SCK) is attached to the top of R105 (or 106?) Magenta (MISO) to the left of R53 and Green (MOSI) goes a long way but doesn't seem to be connected to anything - can I get a closeup of the right side of the front around the green dot?

We're trying to trace these pins?
9 (SCK), 10 (MOSI), 11 (MISO), 13 (RST)
And then something like 14 (5v VCC) & 15 (GND)

Yup, I added coloured dots on the vias on both sides and only lines on traces where required (green).  5v and GND probably go to something LED related, I didn't think to do them (damn stupid disease!)


Where would 5V and GND be located on the pcb? I'm trying to understand the pictures at the moment and I think I read something that said jumper cables and simply go through the holes? Or would they need to be soldered onto the back when following the trace back.

I saw that you made colored dots on the back of the PCB and I will have to inspect that now.

Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #20 on: Wed, 16 June 2021, 23:00:00 »
You'll need to supply power to the controller to flash it.  The AVR programmer has a switch on the side to turn the power on/off.
I'd recommend using the programmer to power the PCB rather than trying to power it over USB - good chance you fry it and the programmer at the same time.

I've been meaning to ask what's up with the USB port?
Those solder points look a bit gnarly.
270751-0

We're basically looking for safe places to hook up to these pins (or 34 and 35 for 5V and GND - lots of options for power):
270753-1

Any chance you've got a multimeter handy?
« Last Edit: Wed, 16 June 2021, 23:05:57 by MajorKoos »

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #21 on: Thu, 17 June 2021, 02:07:10 »
You'll need to supply power to the controller to flash it.  The AVR programmer has a switch on the side to turn the power on/off.
I'd recommend using the programmer to power the PCB rather than trying to power it over USB - good chance you fry it and the programmer at the same time.

I've been meaning to ask what's up with the USB port?
Those solder points look a bit gnarly.
(Attachment Link)

We're basically looking for safe places to hook up to these pins (or 34 and 35 for 5V and GND - lots of options for power):
(Attachment Link)

Any chance you've got a multimeter handy?


I'm certain that when I received the PCB, they weren't looking too hot and I tried to fix it but was already frustrated with the PCB having issues, so I didn't go back to it. I have since then fixed it with a little help of flux and it looks much better (I hope).

And I do have a multimeter! I just don't know how to use it very well, so I could watch a video or two to get me a good idea of what I'm looking for. However, I'd also appreciate any tips or directions on what I should do.

So I would technically have to solder jumper cables directly to the micro controller? I have no quarrels with soldering, but this would definitely be the first time touching a micro controller if that were the case.

Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #22 on: Thu, 17 June 2021, 06:17:10 »
The aim is not to solder to the controller as the pins are tiny.

Put the multimeter in continuity or diode test mode (so when you touch the probes it beeps or flashes or ... whatever it does) and check as in this pic - pink pin on the controller to the left of R53, Cyan to the top of R105 (or 106?) and green to the pins on the left side of the circled chip (which I'm hoping is big enough to solder to) as the via comes out under the chip so can't tell exactly where it goes.

270763-0

I have to go to work now so the others will have to wait.
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #23 on: Thu, 17 June 2021, 13:18:03 »
The aim is not to solder to the controller as the pins are tiny.

Put the multimeter in continuity or diode test mode (so when you touch the probes it beeps or flashes or ... whatever it does) and check as in this pic - pink pin on the controller to the left of R53, Cyan to the top of R105 (or 106?) and green to the pins on the left side of the circled chip (which I'm hoping is big enough to solder to) as the via comes out under the chip so can't tell exactly where it goes.

(Attachment Link)

I have to go to work now so the others will have to wait.

So I just checked the locations with the colored dots and the multimeter is making a sound in continuity mode. So I think I can at least confirm that much.

Looking at the pins of the green circled chip, I would like to think it's a reasonable enough size to solder a jumper onto it. Is there anything else I would need to check?

I'm guessing that after figure out all the locations my only concern would be that I mess up the soldering.

Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #24 on: Thu, 17 June 2021, 16:57:23 »
You need to identify which pin on the rectangle chip is the green one, you can also try and follow the 5v or GND pins to find somewhere to put them if you're bored.  If not I'll give it a go in 20+ hours but the pic wont beep or flash at me to tell me I'm right
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #25 on: Fri, 18 June 2021, 08:21:21 »
You need to identify which pin on the rectangle chip is the green one, you can also try and follow the 5v or GND pins to find somewhere to put them if you're bored.  If not I'll give it a go in 20+ hours but the pic wont beep or flash at me to tell me I'm right
Show Image


Of course yeah, I'll give it a go. Would there be a starting place for me to do so?

I'll do some Googling as well to get me started. As for the rectangle chip, which connection will I be identifying?

Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #26 on: Fri, 18 June 2021, 09:16:49 »
I'm on a slow mobile in battery saving mode so scrolling is painful let lone loading a fullsize pic so I'll just call it the green one - the green leg on the square chip should be connected to one of the circled legs on the rectangle.  There's a good chance GND and 5v also connect to the rectangular chip so you can try testing them to the pins MajorKoos mentioned.
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #27 on: Fri, 18 June 2021, 14:05:32 »
I'm on a slow mobile in battery saving mode so scrolling is painful let lone loading a fullsize pic so I'll just call it the green one - the green leg on the square chip should be connected to one of the circled legs on the rectangle.  There's a good chance GND and 5v also connect to the rectangular chip so you can try testing them to the pins MajorKoos mentioned.

If I did it correctly, the green line/dot on the microcontroller (as depicted by the picture with your annotation) leads to the top pad of R55.

I'm not sure if I understood following traces properly, but I had to keep going from back to front to follow the trace.

So with my currently understanding, I need to follow the traces of the pins that MajorKoos mentioned?

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #28 on: Sat, 19 June 2021, 19:49:32 »
Update: So I believe I managed to wire it correctly and I think I burned a new bootloader and updated the firmware. However, I'm not actually certain if I successfully did so as QMK still isn't recognizing the PCB by itself (when it isn't wired to the ISP programmer).

This is as far as I've gotten and I'm not really sure where to go from here.


Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #29 on: Sun, 20 June 2021, 00:10:22 »
If AVRDude reported success then you managed to write something onto the chip which is progress.
What does it show up as in device manager and QMK toolbox when plugged into USB?


Offline MajorKoos

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #30 on: Sun, 20 June 2021, 09:12:20 »
In If the bootloader was successfully burned to the controller Windows should detect the PCB when plugged into USB and you should be able to flash the firmware onto the PCB over USB using QMK toolbox.  If it's not being picked up in windows I'd look at the bootloader.  Which bootloader did you flash onto the PCB?

https://github.com/qmk/qmk_firmware/blob/master/docs/isp_flashing_guide.md
Also, avoid changing the efuses if you can help it - it could brick the PCB if not done correctly.
« Last Edit: Sun, 20 June 2021, 09:33:30 by MajorKoos »

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #31 on: Sun, 20 June 2021, 13:09:36 »
If AVRDude reported success then you managed to write something onto the chip which is progress.
What does it show up as in device manager and QMK toolbox when plugged into USB?


Yeah so AVRdude reported that there was a success, but when I plug in the PCB by itself it still isn't recognized by Windows (same error was the thread title). But now that also makes me wonder if I did it properly as in if the programmer was relaying it to the PCB? I think I did the wiring correct but now it makes me question if I properly followed the trace for MOSI (top of R55).

The bootloader that I burned was for the ATmega32u4 as stated on the microcontroller. I copied the raw code for the bootloader and pasted it into a text editor and saved it as a HEX file. I'm not sure if I was supposed to edit anything but since AVRdude said success I figured everything was okay.


Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #32 on: Sun, 20 June 2021, 15:53:21 »
Where is R55? If you got continuity between the controller and R55 that means you found an acceptable place to solder to, I'm just intrigued as it's not near R54 (left side of the middle row) or R56 (right side of the middle row) nor near the rectangle chip where I thought it went.

There is more than one bootloader that will work on the ATmega32u4 chip so while there is no wrong answer to the question 'which bootloader did you flash' there is an answer, a link would be good if you don't know the name of the one you used.  Most importantly if the bootloader you chose has a different size to the one the firmware expects the firmware will be in the wrong memory address on the chip and wont load.
120/100g linear Zealio R1  
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #33 on: Sun, 20 June 2021, 16:49:05 »
Where is R55? If you got continuity between the controller and R55 that means you found an acceptable place to solder to, I'm just intrigued as it's not near R54 (left side of the middle row) or R56 (right side of the middle row) nor near the rectangle chip where I thought it went. And now that you mention it, I'm a doofus because I did not check for continuity to R55.

There is more than one bootloader that will work on the ATmega32u4 chip so while there is no wrong answer to the question 'which bootloader did you flash' there is an answer, a link would be good if you don't know the name of the one you used.  Most importantly if the bootloader you chose has a different size to the one the firmware expects the firmware will be in the wrong memory address on the chip and wont load.


I would certainly trust your judgment over my own, so I'll give those a shot. R55 is in the top left corner (when backside is facing you) of the PCB, slightly below the top-left underglow RGB.

I connected 5v and GND to the rectangle chip, although I placed them at different ones. I wouldn't think that power would be an issue though since the PCB did have a glow of red RGB in the previous image that I included. However, I do think MOSI might be my issue since that was the only one that I tried to figure out myself (and likely failed lol).

Here is the link for the bootloader that I used: https://github.com/qmk/qmk_firmware/blob/master/util/bootloader_atmega32u4_1.0.0.hex


Let me know if there is another one that I could possibly try. In the meantime I will try out the different positions for finding the connection for MOSI.


Oh and if it helps, the rectangle chip is a 74HC237D.
« Last Edit: Sun, 20 June 2021, 16:53:11 by sanlouie_7 »

Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #34 on: Sun, 20 June 2021, 17:00:42 »
Where is R55? If you got continuity between the controller and R55 that means you found an acceptable place to solder to, I'm just intrigued as it's not near R54 (left side of the middle row) or R56 (right side of the middle row) nor near the rectangle chip where I thought it went. And now that you mention it, I'm a doofus because I did not check for continuity to R55.

There is more than one bootloader that will work on the ATmega32u4 chip so while there is no wrong answer to the question 'which bootloader did you flash' there is an answer, a link would be good if you don't know the name of the one you used.  Most importantly if the bootloader you chose has a different size to the one the firmware expects the firmware will be in the wrong memory address on the chip and wont load.


I would certainly trust your judgment over my own, so I'll give those a shot. R55 is in the top left corner (when backside is facing you) of the PCB, slightly below the top-left underglow RGB.

I connected 5v and GND to the rectangle chip, although I placed them at different ones. I wouldn't think that power would be an issue though since the PCB did have a glow of red RGB in the previous image that I included. However, I do think MOSI might be my issue since that was the only one that I tried to figure out myself (and likely failed lol).

Here is the link for the bootloader that I used: https://github.com/qmk/qmk_firmware/blob/master/util/bootloader_atmega32u4_1.0.0.hex


Let me know if there is another one that I could possibly try. In the meantime I will try out the different positions for finding the connection for MOSI.


Oh and if it helps, the rectangle chip is a 74HC237D.

Just for an update, I checked R55 and there was continuity between the MOSI pin on the microcontroller to the top pad of R55. Surprisingly, R54 and R56 did not work.

Offline suicidal_orange

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #35 on: Sat, 26 June 2021, 03:02:12 »
I think I've found the problem - by changing the bootloader you've changed what the chip says it is and now you need to install the drivers for the QMK bootloader.  Hopefully that's just a button in the toolbox?
120/100g linear Zealio R1  
GMK Hyperfuse
'Split everything' perfection  
MX Clear
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Offline sanlouie_7

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Re: PCB "Unknown USB (Device Descriptor Request Failed)" Issue
« Reply #36 on: Tue, 06 July 2021, 19:32:00 »
I think I've found the problem - by changing the bootloader you've changed what the chip says it is and now you need to install the drivers for the QMK bootloader.  Hopefully that's just a button in the toolbox?


I just tried reinstalling QMK Toolbox and updating the drivers, then burning the bootloader using the AVR programmer. Unfortunately, there still hasn't been any change.

I think the only good thing is that windows still recognizes the PCB as a device as a couple days ago, it did not.

Would there be a list of bootloaders that I could try? I use the one on QMK's website and another one that I found, but I think that one gave me the issue with Windows not recognizing the device.

I'm still interested in giving the PCB a go. Although at this point it looks like I'll have to hope another GB runs for hardware, or I find someone willing to sell a PCB on the aftermarket  :-X