[Request] [Jolla Tablet] Multiple USB Ports [answered]
asked 2014-11-20 19:44:41 +0200
I listen to a lot of music on my phone and tablet. I prefer to listen to it through my FiiO E17 and with recent updates to Android I have been able to do so on my phone and tablet, which is an extremely nice feature. I hope it is supported in Sailfish OS! There is an issue with doing this, however, because it takes the only USB port on my device and that USB port is also used to charge the battery on both devices. This means my device won't charge and that doesn't end up very well when I'm listening in my car and running Waze at the same time (GPS + Music - Charging = Dead Soon).
There are USB splitters and hubs, etc., of course, but they still don't allow the phone to charge. Unfortunately the (current, "fixed" in USB 3.1) USB standard does not support high speed (i.e. sound streaming) and high-power modes at the same time. On a laptop, desktop, etc. this wouldn't be a problem because it has a separate charging port, but phones and tablets (so far) have not had this feature.
So my request is to get a second micro-USB port added to the Jolla tablet. I would hazard a guess that it would be significantly easier to implement an "everything" port and a "data-only" port. i.e. You would have one port that functions as it does now (charging and syncing to the computer, using USB OTG, etc.) and one that could only be used for data that would not be hooked up to the battery charging IC. I haven't looked into the battery charging IC's used by most manufacturer's these days, though, so maybe they support multiple inputs.
So yeah, second USB port on the tablet.
Not so sure if it would be that easy. And it's going to be fun to mix up those two ports if the functionality is different...
Philippe De Swert ( 2014-11-20 19:51:45 +0200 )editIt definitely wouldn't be EASY, but it wouldn't necessarily be HARD, either.
By far the easiest way to do it would be to have one port that is JUST for charging and one port that is JUST for data. Then you would just split the single 4-trace path you are using right now into 2 2-trace paths, one going from the charging port (carrying only + and -) to the charging IC and the other going from the data port (carrying D+ and D-) to wherever the USB data normally hooks up (not sure if it is normally directly wired to the SoC or if there is a USB controller IC that is hooked to the SoC through some other protocol).
Doing it with 2 data connections and one charging connection either your SoC would have to support 2 USB data inputs or you would need to add a suitable controller to interface with the SoC and act as a hub.
Doing it with 2 charging and one data you would either need to combine the power leads from the 2 USB ports (and then make sure the combined power wouldn't overload the charging IC) or you would need a charging IC with 2 distinct +,- inputs (and I don't know if that exists or not).
As for mixing the ports up it wouldn't cause any huge problems other than people wondering why there phone wasn't charging. You could put them on different sides of the phone or put a cover over one or do something else to differentiate. Plugging the power cord into the data port wouldn't do anything adverse as you could simply advertise that you didn't want that current (USB protocol has methods of negotiating current requirements to support different device types). Or you could do whatever the charging IC does when it's charged (I'm honestly not sure what they do, maybe just don't complete the circuit for the power lines?).
Anyway, I think it's certainly feasible. At least technically. Although probably not at this stage of development for the tablet project.
Kumouri ( 2014-11-20 20:03:32 +0200 )editI would love if they either make a separate charging port and 1 usb or multiple usb ports. idc which is the easier way but i think especially on a hackable x86-64 device being able to use USB while charging is a must have.
michel ( 2014-11-25 18:20:44 +0200 )edit