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

Posted: Wed Mar 20, 2024 7:25 am
by anees.ahmad.jaffer
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 1338 times
Here is my PCB design:
Screenshot 2024-03-20 090851.jpg
Screenshot 2024-03-20 090851.jpg (602.06 KiB) Viewed 1338 times

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

Posted: Thu Mar 21, 2024 3:07 am
by ESP_Sprite
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 1218 times

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

Posted: Sun Mar 24, 2024 9:54 pm
by anees.ahmad.jaffer
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?

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

Posted: Mon Mar 25, 2024 12:38 am
by ESP_Sprite
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.