No DFU detected, usb device not recognized code 43

[HaYa6174]

I am trying to create a custom keyboard, and I was trying to flash my board with stm32f070c6t6 MCU in DFU mode using cube programmer, but I keep getting "no DFU detected" (of course while pulling BOOT0 pin high).

Also, every time I plug my device into my PC, the error message says, "Windows has stopped this device because it has reported problems (Code43). A request for the USB device descriptor failed."

I am new to this field, so I am running out of ideas.

I put 16MHz crystal and set up 48MHz for USB, I configured the device description based on this website; https://controllerstech.com/how-to-use-stm32-as-a-keyboard/

I pulled up D+ with a 1k5 resistor, I pulled down both CC1 and CC2 with 5k1 resistors. 

  

I checked the voltage on the regulator and found it was totally fine (both 3v3 and 5v). I also checked the soldering and made sure that no pins were bridging.

I managed to flash the chip using STlink recently, but since this board is designed to be a keyboard, I expect the USB to work fine.

I am feeling so stuck, I have already spent like a total of 10 hours trying to figure it out, so it will be really helpful if someone tells me where I made a mistake.

Thanks.

[HaYa6174]

I checked the datasheet, and I am pretty sure that those were not mixed up. (PA12: D+, PA11: D-) 

Also, pin speed is not configurable apparently.

I will try removing C18.

[HaYa6174]

I removed the C18, but it did not work... no DFU target + no USB error

Edit: no USB error meant the error "USB device not recognized", sorry for my *** explanation... 

This is my PCB design for a USB data line... I hope this routing is ok...

[AScha.3]

Routing looks ok...so far, i can see it; just at U5 : is the line D+/- here connected inside this chip ? did you check continuity ?

+

read:

> no USB error

Good. So its doing nothing now...also nothing wrong. :) So try power up  with boot0 hi... and see dfu in CubeProgrammer...

[HaYa6174]

According to the datasheet from ST, USBLC6-2SC6 (the U5 chip) is internally connected (at least that is what I thought). 

https://www.st.com/content/ccc/resource/technical/document/datasheet/06/1d/48/9c/6c/20/4a/b2/CD00050750.pdf/files/CD00050750.pdf/jcr:content/translations/en.CD00050750.pdf

I am unsure what I should do for the datasheet for the device bootloader. Should I erase my code before trying DFU mode?

And sorry for my poor explanation, still I am getting the same error :(

[AScha.3]

You don't need to erase, if bootloader running, you can flash, erase etc.

Just on your layout, D- close to CPU has a via, but there is also another connection to red track and to a pin. What is this?

Can you look with a scope to the signal at the CPU pins, to prove the signal looks ok?

[HaYa6174]

 Sorry for the late reply!

Here is the close-up.
the orange line on the USBD- via is just a silksceen.

[FBL]

Hi @HaYa6174 

1. It's crucial to measure the exact lengths to ensure they are within the acceptable tolerance.
2. The differential pair should have a controlled impedance: 90ohms differential. Ensure that the trace width and spacing are properly designed. Check your PCB stack-up and dielectric material.
3. Spacing between the D+ and D- traces should be consistent throughout their length to maintain impedance.
4. Avoid sharp bends and minimize Vias
5. Maintain isolation from other high-speed signals and ensure good ESD design

[HaYa6174]

Thank you for the info.

I used KiCad's differential routing tool, assuming those traces are almost the same length and maintaining close distance, and I also tried to minimize sharp corners and vias.
I also tried not to allow any other traces to cross the USB data line, and when I needed to do so, I made sure that it crossed perpendicular to the USB data line.

But, I am not sure about the 90ohm impedance rule; I knew that it existed, but I am not sure how to actually achieve that.

What should I do?

[AScha.3]

Afaik in kicad main menu is tools/... , pcb tools or so, there is a impedance calculator

(track width x distance to ground plane in pcb material -> approx. impedance )

+ no need to match this +/- 1 ohm ; just it should be in range 70...110 ohms (center of range is 90 ohms).

Because it should match the cable , as good as possible, so it should be :

>

The USB 2.0 specification stipulates an impedance between 76.5 and 103.5 Ω for the cable when measured during differential transmission.

<

[HaYa6174]

I searched a little about this and tried to calculate using the KiCad calculator tool. Then I got Zeven: 189.26 and Zodd: 67.822.

This is mostly because I designed the board with only 2 layers, meaning that the distance between the ground plane and D+- was about 1.6mm (the board thickness)...

I assume those numbers aren't great, should I redesign it with 4 layers?