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Hypex
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AmigaOne/XE on board USB ports can actually work! :-O Posted on 22-May-2018 14:47:13
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Elite Member |
Joined: 6-May-2007 Posts: 11328
From: Greensborough, Australia | | |
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tonyw
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Re: AmigaOne/XE on board USB ports can actually work! :-O Posted on 22-May-2018 22:19:24
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Joined: 8-Mar-2003 Posts: 3240
From: Sydney (of course) | | |
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| @Hypex
Your UBoot code possibly knows how to enable the terminating resistors, so making it all work without external resistors. Since we never found out how to do it from the VIA docs, OS4 was unable to enable the internal resistors and it only worked properly with external resistors.
_________________ cheers tony
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Hypex
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Re: AmigaOne/XE on board USB ports can actually work! :-O Posted on 23-May-2018 4:24:54
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Joined: 6-May-2007 Posts: 11328
From: Greensborough, Australia | | |
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| @tonyw
Quote:
Your UBoot code possibly knows how to enable the terminating resistors |
I'm not sure what you mean here. I didn't write any UBoot code. Do you mean UBoot itself? In that case if UBoot knows what it is doing is the USB controller then reset again once an OS loads up? And also being the source of UBoot was available, was it handling the USB controller differently, if this was examined?
In any case, regardless of UBoot knowing anything special with the USB ports, as discovered there are USB devices that work simply as they are. In both UBoot and in OS4/Linux. They are detected when plugged in and detected when pulled out. If you have had a working A1 you would be able to check this.
I do wonder what is different with the devices I have. Perhaps they have built in resistance as part of the electronic design that somehow has the effect of the USB ports working, I don't know. I didn't check them with a multi-meter. |
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tonyw
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Re: AmigaOne/XE on board USB ports can actually work! :-O Posted on 23-May-2018 7:57:33
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Elite Member |
Joined: 8-Mar-2003 Posts: 3240
From: Sydney (of course) | | |
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| @Hypex
I meant in the old faithful U-Boot code. I doubt that the people who used it for the A1 SE/XE boards ever looked at it carefully in that respect.
We know that it is possible to enable/disable the terminations, since PC designs using the VIA 686B were able to do it. However, the docs don't mention it and AFAIK no one ever discovered how to do it. There may be Linux code that one could use, I dunno. It's ancient history these days, since most SE/XE boards were "fixed" by having external resistors soldered on to the back of the board.
The USB "discovery/mount" process depends on the terminating resistors being there, because it measures the voltage on the data lines and thus determines whether something is connected or not.
_________________ cheers tony
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Hypex
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Re: AmigaOne/XE on board USB ports can actually work! :-O Posted on 23-May-2018 15:56:34
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Joined: 6-May-2007 Posts: 11328
From: Greensborough, Australia | | |
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| @tonyw
Yes I thought you meant the UBoot code.
Well with the Linux kernels I tested up to the newest Geri compiled none were able to enable any kind of resistors that I noticed. And I confirmed this by testing the back USB ports with devices that don't get detected without hardware work arounds.
The only difference I could see in Linux is that is was able to use the VIA USB2 card I put in a PCI slot. And do USB2 transfers. OS4 could not and always gave errors. So I had to disable EHCI on OS4 until I found an NEC USB2 card and just gave up on the VIA card working with OS4. It was also at this point that I removed my own USB easy fix since I was migrating my front USB ports to the USB2 card.
But as to discovery, some how the Sandisk USB sticks I have tested here, have something inside that enables this process to work. Perhaps it is accidental and triggers something unexpected in the USB port that just happens to activate the electronics needed. I don't know. I just know that to my surprise there are some devices that can be plugged right in and be detected. So wanted to share this with the Amiga world. |
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billt
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Re: AmigaOne/XE on board USB ports can actually work! :-O Posted on 25-May-2018 3:06:37
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Joined: 24-Oct-2003 Posts: 3205
From: Maryland, USA | | |
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| @Hypex
Does your extension cable have resistors built into it? _________________ All glory to the Hypnotoad! |
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Hypex
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Re: AmigaOne/XE on board USB ports can actually work! :-O Posted on 25-May-2018 5:38:36
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Joined: 6-May-2007 Posts: 11328
From: Greensborough, Australia | | |
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| @billt
Good question. Not that I know of. It's an off the shelf cable, I didn't make it up myself. I should test that. Or pull the tower out again and plug it directly in the back. But I have to remove all the cables above it then try and put them back again. even with a torch it's hard enough. |
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