Timeline for How critical is PCB layout for USB Full-Speed?
Current License: CC BY-SA 4.0
28 events
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| Nov 6, 2020 at 15:00 | history | tweeted | twitter.com/StackElectronix/status/1324728272098369538 | ||
| Sep 11, 2020 at 7:49 | comment | added | FourierFlux | 12 Mbs is pretty slow, try to have shorter traces though. If you're talking USB 3.0 that's another story. | |
| Sep 11, 2020 at 7:19 | history | edited | Rohit Garg | CC BY-SA 4.0 |
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| Jan 15, 2019 at 17:01 | history | bumped | CommunityBot | This question has answers that may be good or bad; the system has marked it active so that they can be reviewed. | |
| Dec 7, 2018 at 13:11 | comment | added | Peter Smith | I see a couple of potential issues. There are 2 devices on the D0 pair (one physical device per pair only), and the two lower devices are pulling both DP and DM down where the detection requires a pull-up on either DP or DM. See ftdichip.com/Support/Documents/TechnicalNotes/… | |
| Dec 7, 2018 at 10:59 | answer | added | JuhoR | timeline score: 3 | |
| Dec 5, 2018 at 19:41 | comment | added | Ale..chenski | If D+ goes HIGH, do you see it toggles down for 200-300 ms ? (USB_RESET)? You should get the hub diagnostics utilities from USB.ORG/developers, something like USB20CV.exe (Command Verifier) and check what is wrong with your port configuration. | |
| Dec 5, 2018 at 17:51 | comment | added | Rohit Garg | @Ale..chenski yes i did try the tree view. Also, I used the USBView softwsre too. Screenshots here: e2e.ti.com/support/interface/f/138/p/752106/2780059#2780059 The downstream D+ line does pull high when I connect a device. But cannot seem to enumerate on host. | |
| Dec 4, 2018 at 0:09 | comment | added | Ale..chenski | A bit strange is that the 1.1 hub gets USB3 driver. Did you try USBTreeView? And again, do any pull-ups appear on downstream ports when you attach devices? | |
| Dec 3, 2018 at 22:21 | comment | added | Rohit Garg | @Ale..chenski I have attached the Device Manger capture. Doesn't that indicate that the hub is enumerated? | |
| Dec 3, 2018 at 22:20 | history | edited | Rohit Garg | CC BY-SA 4.0 |
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| Dec 3, 2018 at 22:16 | comment | added | Ale..chenski | You said "hub gets enumerated". Are you sure that it is enumerated, but not just "detected"? When you connect a downstream device, do you see any pull-up on any D+ or D- wires downstream? | |
| Dec 3, 2018 at 22:15 | comment | added | Rohit Garg | @RichardtheSpacecat Sorry for the careless mistake in the schematic. They do share a ground with the rest of the circuit. I have the 2nd upstream USB port as an extra optional USB connector(using only one of them at a time, but wanted that for hardware testing). | |
| Dec 3, 2018 at 22:10 | comment | added | Richard the Spacecat | Why are ports 1 and 2 in parallel to each other? Why don't those share at least a common ground with the rest of the circuit? (Judging from the schematic) Is this an attempt at connecting one USB hub to multiple hosts? | |
| Dec 3, 2018 at 22:01 | comment | added | Rohit Garg | @Ale..chenski I have attached the schematic. 15K pull down resistors are required on downstream data lines according to full-speed USB spec. | |
| Dec 3, 2018 at 22:00 | history | edited | Rohit Garg | CC BY-SA 4.0 |
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| Dec 3, 2018 at 21:50 | comment | added | Ale..chenski | You probably should start with your schematics. Why do you have pull-downs on downstream ports? | |
| Dec 3, 2018 at 19:56 | comment | added | Dave Tweed | If your devices, as well as your hub, are custom assemblies, then that's information you've been withholding. I think I'm done here. | |
| Dec 3, 2018 at 19:54 | comment | added | Rohit Garg | @DaveTweed thanks for the explanation. So what I am doing is, I supply VUSB in the cable from an external 5V source (the jumper pin connects to VUSB pin of the micro USB port, which is connects through a cable to a downstream device). I do see the D+ line on the device go high. Correct me if I'm wrong.. | |
| Dec 3, 2018 at 19:37 | comment | added | Dave Tweed | That doesn't matter. You still need the VUSB connection in the cable to enable enumeration. Specifically, there is a pullup resistor on the device that pulls up on either D+ or D- to indicate the type of device. The host or hub pulls down (weakly) on both of these lines, and it's the low-to-high transition that triggers enumeration. Inside the device, this pullup is connected to VUSB coming from the cable, NOT to its internal power supply. If there is no VUSB on the cable, this mechanism doesn't work. | |
| Dec 3, 2018 at 19:10 | comment | added | Rohit Garg | @DaveTweed I am using the jumper headers adjacent the USB ports to supply 5V to VUSB externally.. | |
| Dec 3, 2018 at 18:59 | comment | added | Dave Tweed | Even if all of your USB devices are self-powered, you still need the VUSB connection to each one -- it's what kicks off the enumeration process. | |
| Dec 3, 2018 at 17:10 | comment | added | Rohit Garg | Power is being supplied externally through the jumper pin connection on the bottom edge. The top layer polygon and bottom layer are Gnd. | |
| Dec 3, 2018 at 17:08 | answer | added | Chris Fernandez | timeline score: 0 | |
| Dec 3, 2018 at 17:07 | comment | added | CrossRoads | How are power & Gnd connected to all the devices? I only see signal connections in your layout. | |
| Dec 3, 2018 at 17:01 | history | edited | Rohit Garg | CC BY-SA 4.0 |
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| Dec 3, 2018 at 16:55 | answer | added | Elliot Alderson | timeline score: 3 | |
| Dec 3, 2018 at 16:40 | history | asked | Rohit Garg | CC BY-SA 4.0 |