View Full Version : USB connectivity (hardware related Q)
Hi,
Looking at the FCC photos around USB jack and how it is connected to CPU of WL500G I see that it is identical to my Belkin F5D7230-4, thou on my router none of the components are placed on the PCB.
I was hoping that somebody with hardware skills could measure the resistor values of those four resistors next to the USB jack and post them here. I'm attaching a schema of the USB circuit of Belkin router.
Appreciate any help with adding USB to my router.
Thank you,
Sergiy
Check the image. So,
R733, R734 should be 15 Ohms - they're R53&R54 on the ASUS board and coming from USB connector also they're attached in series with L16, L17 (but you can omit them as seems),
R723, R724 are pull-downs 15K - they're R54 and R53
C731 (CE2) - 330 uF, and there is also C73 100nF in parallel.
Also +5V comes via 0.75A fuse (F2).
Also, there is should pull-up register for USB_CNTRL line - R57, rated with 10K (this is very important, otherwise BCM4702 as seems will not use USB port).
Another picture for second (unused) USB port - will help you to locate parts on your board
R97, R99 - 15K - pull-downs for USB2_N & USB2_P
R178 (not installed) should be 10K - pull-down to disable port (USB_CNTRL) - this should pulled-up to enable it.
Please make a hi-res image of your board.
Thank you Oleg,
This is even more then I was hoping for since I didn't even realize that a pull-up resistor has to be placed on the board in order to enable USB functionality. It seems that on Belkin it is R725. Can you confirm that these two lines that connect to pins B6 and C9 (thou I might be off a pin or two) are indeed USB lines? (Everything so far points to they are, but I thought I'd double check).
As for the second USB port, it would be nice to pull out this one as well, but that would be another project. I see some unpolulated pads on the board around the CPU, these are for resistors: R34, R37, R653, R654, R655, R659 - but it is hard to say where they connected to it.
Thanks again,
Sergiy
just thought I'd add some more info: the R725 seemed to be wired to the B8, and right next to it is a pull-down R889, which is connected to B7 - I wonder if this one has anything to do with USB?
Belkin uses BCM4712, I've no idea of it pinout. BCM4702 uses pins P20,21,22 for usb1 and N20,21,22 for usb2.
You will probably need to check the reverse side of PCB.
There should be pull-downs for the USB2, but who knows. ;-)
Dear Oleg, thank you in advance for posting BCM4702 usb pinout, its quite a beginnig for me to find out the same pins in a BCM4712.
I just want to ask you if you have any method in order to find them out, because its been a while since i have a wrt54g and until now no light about it.
If theres any special technique, please show me a way.
Thanks again.
Luciano