Why is USB 3 port type micro B?


S

sulu

Guest
I'm just scratching my head, why the only USB 3 port on the Pyra is type micro B instead of plain type A.

I'm sure there is a very good reason, probably because it makes sense in some "hardware hackers" scenarios. But as someone who barely knows at which end to pick up a soldering iron, I can't see it.
I'm also sure the answer to my question is already buried somewhere in the forums. But as a relatively new member I don't know where to look.

So from my POV it would have been much more convenient to have the USB 3 port be type A and use an "A/micro B" adapter for the presumed rare cases where micro B would be more useful.
As it is I find myself looking for the most space-efficient way to turn the micro B port into type A.
The only thing I've come up with right now is to take one of the short "micro B(m)/A(m)" cables I already have and get an "A(f)/A(f)" adapter for it. But since there will usually be a type A(m) cable going into the adapter, the first cable seems to be useless overhead to me. I would think the shortest possible but wide* adapter from micro B(m) to A(f) should be best. But I can't find anything like that.


*) to minimize leverage stress on the port
 

slaeshjag

¯\_(ツ)_/¯
Joined
Apr 8, 2010
Messages
2,687
Location
~Stockholm, Sweden
The USB3 port is the only port that can act as a client port. With an OTG adapter, it should be usable as a host port. USB A or C can't dynamically decide if it's a host or a client.
 

Letalis Sonus

Advanced Member
Joined
Mar 5, 2009
Messages
1,483
The SoC only has a single USB 3.0 port and you can't split up the client and host parts into different jacks, it simply makes sense to offer the only available USB 3.0 port as OTG.

Do you even search, bro?
 
S

sulu

Guest
Limitation of the SoC.
I know the SoC only supports one USB 3 port.

The USB3 port is the only port that can act as a client port. With an OTG adapter, it should be usable as a host port. USB A or C can't dynamically decide if it's a host or a client.
Why can't type A work as an OTG port? Afaik the port type is only a mechanical issue.
Sure, micro B is more useful in client mode, but I'd guess that an adapter would still work and that using the USB 3 port in host mode would be more common than using it in client mode.
[doublepost=1476307312,1476307154][/doublepost]
The SoC only has a single USB 3.0 port and you can't split up the client and host parts into different jacks, it simply makes sense to offer the only available USB 3.0 port as OTG.

Do you even search, bro?
1. I did search. Please point me to the answer if I missed it!
2. Who said something about splitting up the port?
3. I'm pretty sure I'm not your "bro".
 

Yoyobuae

Very Active Member
Joined
Oct 23, 2009
Messages
839
Why can't type A work as an OTG port? Afaik the port type is only a mechanical issue.
Sure, micro B is more useful in client mode, but I'd guess that an adapter would still work and that using the USB 3 port in host mode would be more common than using it in client mode.
Slightly longer explanation: Because standards:
MicroUSB Specification to the USB 2.0 Specification said:
Code:
The purpose of this document is to define the requirements and features of a
Micro-USB connector that will meet the current and future needs of the Cell
Phone and Portable Devices markets, while conforming to the USB 2.0
specification for performance, physical size and shape of the Micro-USB
interconnect.
[...]
A-Device A device with a Type-A plug inserted into its receptacle. The A-device
         supplies power to V BUS and is host at the start of a session. If the
         A-device is On-The-Go, it may relinquish the role of host to
         an On-The-Go B-device under certain conditions,
[...]
B-Device A device with a Type-B plug inserted into its receptacle. The B-device
         is a peripheral at the start of a session. If the B-device is OTG, it
         may be granted the role of host from an OTG A-device.

On-The-Go and Embedded Host Supplement to the USB Revision 2.0 Specification said:
Code:
This specification defines these non-PC hosts as Targeted Hosts. A Targeted Host
is a USB host that supports a specific, targeted set of peripherals. The
developer of each Targeted Host product defines the set of supported peripherals
on a Targeted Peripheral List (TPL). A Targeted Host needs to provide only the
power, bus speeds, data flow types, etc., that the peripherals on its TPL require.

There are two categories of Targeted Hosts:
1. Embedded Hosts: An Embedded Host (EH) product provides Targeted Host
                   functionality over one or more Standard-A or Micro-AB
                   receptacles. Embedded Host products may also offer USB
                   peripheral capability, delivered separately via one or more
                   Type-B receptacles.
2. On-The-Go: An OTG product is a portable device that uses a single Micro-AB
              receptacle (and no other USB receptacles) to operate at times as
              a USB Targeted Host and at times as a USB peripheral. OTG devices
              must always operate as a standard peripheral when connected to a
              standard USB host.

Also, from what I understand, it was designed this way to prevent any cases of connecting the wrong devices with the wrong cables (and/or adapters). USB peripherals always have Type B or micro-B receptacles. And USB OTG cable is the standard way allow USB device with micro-B receptacle to have USB Type A receptacle and have USB Host capabilities.

Besides, being able to act as USB peripheral is very useful (Master Control PND = Pandora as USB keyboard/mouse/joystick, ISO CDROM PND = Pandora as USB HDD/CDROM).
 
Last edited:

Penguin-Guru

Still Fresh
Joined
Sep 29, 2016
Messages
42
I think there are a lot of threads about this already but this is relevant to my interests so I'll post anyway. I believe Type-C does not require an OTG pin to negotiate the connection type, it's probably handled digitally. Maybe somebody more familiar with this tech could confirm?

My current understanding is that U.S.B. Type-C just wasn't a safe bet when the decision was made. These technologies do often fail to take off and, although I think U.S.B. Type-C looks awesome, it still hasn't established the market share I expected. I suspect this is due to manufacturers struggling with the very new mechanisms for negotiating connections, but it's just a guess. I really don't know anything about this stuff.

Source: https://www.quora.com/Is-OTG-supported-in-USB-Type-C

Potentially interesting reference sourced from above link: [doublepost=1476333771,1476333535][/doublepost]Sorry for the funky iframe. I don't know what it looks like to other people so I'll just leave it as is... Here's a link to the same page on Amazon.
 

Yoyobuae

Very Active Member
Joined
Oct 23, 2009
Messages
839
I think there are a lot of threads about this already but this is relevant to my interests so I'll post anyway. I believe Type-C does not require an OTG pin to negotiate the connection type, it's probably handled digitally. Maybe somebody more familiar with this tech could confirm?
From what I understand USB Type-C cable is a bit more complicated than previous cables. Which can end up causing problems:
https://www.cnet.com/news/usb-type-c-cable-problems/
http://www.theverge.com/2016/2/4/10916264/usb-c-russian-roulette-power-cords

Guess making sure to buy only cables already vetted to work properly could avoid those issues. Or maybe later on manufacturers do a better job at making safe cables.
 
S

sulu

Guest
Anyone have a link to the required adapter?
What adapter? To turn the Pyra's micro B port into type A?

Well, my idea was to take one of the A/micro B cables I already have from several external USB 3 HDDs. Their ends look like the ones on this cable [1], but mine are "only" 20cm long. Then I'll also get an A/A adapter that is "female" on both ends, like this one [2]. I have a similar combination working to connect USB devices to my Nokia N900, but it's only USB 2.

I've also just found a USB 3 adapter that translates straight from micro B(m) to type A(f). [3] But for a stiff adapter it's too long for my liking, so I'd be worried to damage the Pyra's port if I'm not careful. If it had just a tiny bit of cable between the ends it would be perfect.

Edit:
This [4] is exactly the type of cable I was looking for. It could still be a bit shorter though.
... or this one. [5] ;)


[1] http://geizhals.eu/various-usb-3-0-cable-a-micro-b-0-5m-a825111.html
[2] http://geizhals.eu/inline-usb-3-0-adapter-35300x-a1109898.html
[3] http://geizhals.eu/inline-usb-3-0-adapter-35300s-a1109901.html
[4] http://geizhals.eu/logilink-usb-3-0-otg-cable-aa0048-a1125621.html
[5] http://geizhals.eu/inline-usb-3-0-cable-micro-b-a-plug-0-15m-31609-a1428104.html
 
Last edited by a moderator:

Yoyobuae

Very Active Member
Joined
Oct 23, 2009
Messages
839
Anyone have a link to the required adapter?
Search for USB 3.0 OTG cable. Some examples:
https://www.tethertools.com/product/tetherpro-usb-3-0-micro-otg-adapter/
https://sewelldirect.com/usb3-micro-otg-cable-white

It is important that the cable claims to be USB OTG (On-the-go), as OTG cables have special wiring which tells the device (Pyra on this case) to switch to USB Host mode.

I would avoid an adhoc solution with non-standard adapters as mentioned above (sorry sulu).
 

Penguin-Guru

Still Fresh
Joined
Sep 29, 2016
Messages
42
I'm pretty sure legacy O.T.G. wouldn't work if adapted to/from Type-C, though. That would require active negotiation circuitry, or perhaps modern drivers for legacy U.S.B. will support this in-band?

From what I understand USB Type-C cable is a bit more complicated than previous cables. Which can end up causing problems... Guess making sure to buy only cables already vetted to work properly could avoid those issues. Or maybe later on manufacturers do a better job at making safe cables.

Yeah, I think that's not really related to the specifications. Low quality manufacturing is not a new issue, and addressing this is one of the Pyra's selling points. Cable and laptop quality in particular have been building to a head over the past 8+ years. I'm not sure how I feel about putting resistors in the cable, but as long as the host bus controller is properly designed, I don't think this should be a concern. Interesting read, though.
 

Kasil

Still Fresh
Joined
May 13, 2016
Messages
10
Just being curious and as I have none, will the Pyra come with a USB3 OTG cable ?
 

levi

Still fresh, damnit!
Joined
Oct 6, 2008
Messages
14,372
Location
Somewhere off the coast of the EU
It's unlikely, as last time I looked at the box prototypes, there wasn't even space for shipping a charge cable, but I hope ED will stock those in the shop for those of us without good, reliable USB->micro cables, and maybe he could also stock OTG cables. But either way, as this thread has shown, USB3 OTG cables are not hard to find.
 
Top