USB-C to USB-C not working, USB-C to USB-A working, have pulldowns

anees.ahmad.jaffer
Posts: 11
Joined: Wed Sep 13, 2023 11:12 am

USB-C to USB-C not working, USB-C to USB-A working, have pulldowns

Postby anees.ahmad.jaffer » Wed Mar 20, 2024 7:25 am

Hi. I have a custom board design that uses USB-C in USB 2.0 mode for data and 5V power. I am aware that in order for a USB-C host to recognise the USB-C peripheral, it requires a 5.1k ohm resistor on both CC1 and CC2. I have placed these resistors on my board. When using a USB-C to USB-A cable, I am able to use the board; it gives power and data. When I use a USB-C to USB-C cable, the board does not power up. I thought it may be the cable, so I tested connecting my phone to my laptop using the USB-C to USB-C cable, and it worked. So the cable does support data and power. For interest, it's the cable that came with a Samsung A24.

Here is my schematic for the USB-C connector:
Screenshot 2024-03-20 090740.png
Screenshot 2024-03-20 090740.png (92.25 KiB) Viewed 1288 times
Here is my PCB design:
Screenshot 2024-03-20 090851.jpg
Screenshot 2024-03-20 090851.jpg (602.06 KiB) Viewed 1288 times

ESP_Sprite
Posts: 9711
Joined: Thu Nov 26, 2015 4:08 am

Re: USB-C to USB-C not working, USB-C to USB-A working, have pulldowns

Postby ESP_Sprite » Thu Mar 21, 2024 3:07 am

That is more or less a configuration I've used extensively and it works fine for me. Are you sure all the pins on the USB connector are properly soldered down? Does it work if you flip the cable connector?

Fwiw, this is my PCB layout:
works.png
works.png (43.3 KiB) Viewed 1168 times

anees.ahmad.jaffer
Posts: 11
Joined: Wed Sep 13, 2023 11:12 am

Re: USB-C to USB-C not working, USB-C to USB-A working, have pulldowns

Postby anees.ahmad.jaffer » Sun Mar 24, 2024 9:54 pm

There was an oversight on my side. The PCB assembly used 1k ohm resistors instead of 5.1k ohm. I changed the resistors, and it works perfectly now.

While I have your attention, are there any suggestions you have for the layout of my tracks? Is there anything I could do better?

ESP_Sprite
Posts: 9711
Joined: Thu Nov 26, 2015 4:08 am

Re: USB-C to USB-C not working, USB-C to USB-A working, have pulldowns

Postby ESP_Sprite » Mon Mar 25, 2024 12:38 am

Don't worry too much about it. You're only working with USB1.1, which will still work OK if you route it over two parallel pieces of wet string; your layout will work perfectly fine.

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