Solder More USB Ports to the Raspberry Pi Zero

Slowly, Raspberry Pi Zeros are falling into the hands of everyone who wants one. Quickly, though, it was realized that one USB port wasn’t enough, and having a single USB OTG port was only just the most economical solution. The Pi Zero does have a lot of test points exposed on the back, and [Peter van der Walt] is clever enough to come up with a 4-port hub you can solder directly to the Pi Zero.

[Peter] has a bit of experience with USB ports on the Pi, and the test points available on the bottom of this cheap and wonderful board provide everything you need to break out the single USB OTG port to a USB hub. We’ve seen this done before with a few tenuous solder connections between the Zero and an off-the-shelf USB hub. [Peter]’s build does it by soldering a USB hub directly to the Pi through these test points. It’s the first purpose built bit of hardware designed for the express purpose of giving the Pi four USB ports while only making it a sliver thicker.

The chip [Peter] is using for the build is the TI TUSB2046B, a device that turns a single USB port into a 4-port hub. This is a part that only costs about $2 in quantity, and the USB connectors themselves are only about $0.60 if you want to build a thousand of these solderable USB hubs. Now you see why the Pi Foundation didn’t include a whole host of ports on the Pi Zero, but it does mean you should be able to pick this board up for under $10 when it’s inevitably cloned in China.

[Peter] doesn’t have this board working yet. In fact, he’s only just sent the Gerbers off to the PCB fab. There will be an update once [Peter] gets the boards back and solders up the tiny but tolerable 0603 parts.

58 thoughts on “Solder More USB Ports to the Raspberry Pi Zero

      1. I have the regular USB cable version of that bought somewhere else. Other than quality issue – someone put in too much hotglue and broke the Ethernet connector, the hardware works fine. Nothing I couldn’t fix. As a matter of fact the windows driver installed effortlessly from the provided mini CD. They had Linux and Mac OS drivers too.

  1. Sweet! I’m planning on removing the last hurdle and making the points where you have to connect to the usb pads use pogo pins for a no-solder solution. hopefully the 4 screw holes will let the pogo pins make a connection good enough for stable usb communication…

          1. @shirly^H^H^H^H^H^Htekkieneet
            These pogo pins are :
            Uncompressed Length: 16.5mm / 0.65″
            Compressed Length: 14.5mm / 0.57″

            So these boards need to be at least .080″ apart with the pogo pin sticking out the back .5″
            Surely you did notice that !?!

          2. Opps, Sorry

            @shirly^H^H^H^H^H^HJarek
            These pogo pins are :
            Uncompressed Length: 16.5mm / 0.65″
            Compressed Length: 14.5mm / 0.57″

            So these boards need to be at least .080″ apart with the pogo pin sticking out the back .5″
            Surely you did notice that !?!

          3. My understanding from that spec is the boards need to be between .57″ to .65″ apart, which means that theres just enough room to sandwich a few usb ports/other things in between the two boards. I wasnt planning on making them back to back, but the cheaper “flat” pins from digikey may make that the more economical solution…

  2. A few suggestions to enhance this otherwise very good idea:
    – Change the USB hub chip from TI’s TUSB2046 to Terminus’s FE1.1, FE1.1s or FE2.1: they are cheaper (you can find 2 pieces for $1.99, free shipping: http://www.ebay.com/itm/2PCs-FE1-1S-USB2-0-HUB-SSOP-28-New-/261964408431), plus they have integrated upstream 1.5KΩ pull-up, downstream 15KΩ pull-down, and serial resistors, integrated 5V to 3.3V and 1.8V regulators, and integrated Power-On-Reset circuit. This would eliminate most of the required components on this board, such as most resistors, and the LD1117AS33 LDO as well
    – provide clearance for the RUN pin and composite video headers too, not only for 40 pin GPIO one
    – put vias instead of simple bottom PCB pads to match the D+/D-/VUSB/GND test point on the Pi Zero board, so that they can be hand-soldered with a soldering iron from the top instead of using reflow. This would require moving some connectors around, though, but everybody with average soldering skills could then mount it
    – provide at least global power control and over-current protection using a simple PTC, or individual over-current protections using dedicated chips like 2x MIC2026-2
    – ESD protection TVS diodes,such as 4x PRTR5V0U2X
    – Add some LEDs?

    1. Wow! Nice part find! Dropping the need for all those pullups frees a lot of space. Might then be able to add overcurrent / tvs / LEDs etc. Had to strip down quite a bit to get it to fit. I am making a revised version asap!

    1. Well D+/D- are below the 3rd microUSB connector, and 5V/GND below the 4th one, I’d like to have accessible through-hole vias to pour solder paste in them, down to the Zero PCB pads! My idea was to move the 3rd ad 4th connectors on the short edges instead.

      1. I see. I would lay the two boards USB edges facing each other, solder wires to the pads and fold the two boards together.
        That would have all USB ports pointing out the case on the same side.

      1. Even for a Pi zero, if you plan to use an USB memory stick or a webcam, you will reach this limit easily, so HS is almost required.

        As for the track length and PCB layout, take a look at this application note from former SMSC:
        http://ww1.microchip.com/downloads/en/AppNotes/en562810.pdf

        Also, take a look at this EEVBlog thread, the OP did a board with the FE1.1s using EagleCAD and posted both schematics and pictures there:
        http://www.eevblog.com/forum/projects/diy-usb-2-0-hub/

        No power control/over-current limitation ESD or LEDs though, so there is still room for improvements!

      2. The schematics for the above application note is here:
        http://ww1.microchip.com/downloads/en/DeviceDoc/evb2513q36bas.pdf

        Very good design, but for a DIY version, you can omit all optional EMC components, except for the ferrite beads on VBUS/GND of each port and keep the TVS diodes too. These BGX50A diodes are the cheapest you can get, as well as the MIC2026 USB power switches.

        Please note the proposed shield/GND connections with R/C networks for ESD protection and ground leveling during connections.

        Please consider using USB-A connectors vs. micro USB ones: they take much more space on PCB, but then you don’t need external adapters for everything yo connect to them. All connectors don’t need to be aligned on the same edge.

        If necessary, use reversed (upside-down) connectors so all original Pi Zero and additional connectors have the correct up/down orientation.

      3. Since no one point it out so far:
        – Make sure that when you route the USB tracks, there is a continuous ground plane on the opposite side of the PCB. There are several spots on this layout where it is not done. Those causes discontinuity on the tracks impedance. The datasheets/app notes would have a guide line on that. I understand that it is not practical to have the track width proper impedance on 2 layers PCB.

        – Make sure that there are sufficient spacing between the connectors so that you can plug regular cables with plastic molding in. Ideally you also want to be able to plug in memory sticks. There is a reason why there are extra space for hub.

          1. Agreed. I did a sample board & outline layout and with standard connector spacing. To keep that board out line, you need to have one connector come in from each end, two from the side. The board in question up top looks like would have interference from most USB-B plug jackets.

  3. Ant then one can ask the question:

    WHY didn’t the foundation do that in the first place – remove the micro usb, and use 3 normal usb’s instead, and the additional price with components bought in quantities would have been 7 (hypothetical, in a few select shops in a few countries) $ instead of 5 (hypothetical, in a few select shops in a few countries) $.

    And the increase in height would have been negligible, but it would have been a totally different and much better product.

    But apparently it is more important to Eben & Co to brag about how good they are to mankind by making a “5$” computer.

    1. Because they already sell this… it’s called the B+. I mean, geez, you can buy the B+ for 20 bucks from some of the distributors now. (I just bought a couple for under $40 out the door because one was an “open box”)

    2. >> “WHY didn’t the foundation”

      @Christian Nobel

      Its their board, they did what they wanted.

      I am sure you can design, manufacture, sell and ship any board you want as well.

      Good Luck

    3. It’s probably just fine for some uses. They probably expected people to come up with solutions that fit their needs. Some use cases need a hub with the full Pi too. When you get to such small boards, you’re going to have a lot of people scrapping about things left off, pleasing them all would get back to a board that’s the size of a B+.

  4. How about GL850G its very commonly used in USB hubs http://www.genesyslogic.com/en/product_view.php?show=21

    And seem to very cheap on aliexpress
    http://m.aliexpress.com/item/32247156574.html

    I bought 20 of these with free shipping for around $6.36 but never used it, this is the same part Olimex use it in their SOM board designs https://www.olimex.com/Products/SOM/AM3352/AM3352-SOM-EVB/open-source-hardware

    Schematics on github
    https://github.com/OLIMEX/SOM/tree/master/AM3352/AM3352-SOM-EVB

  5. That is a possibility, too. However, the GL850 requires an external LDO, so you dont gain that much and loosexsome real estate on board.

    And from my experience, it tends to heat much when operating, and reset from time to time under load. I don’t have these issues with the FE1.1.

    1. Wow thanks squonk I was thinking of using it but now I won’t be. I was thinking of the current issue with multiple devices, does FE1.1 has inbuilt current controller or have to use an external chip ?

    2. From the dataseet, page 7 second paragraph
      > GL850G integrated both 5V to 3.3V and 3.3V to 1.8V voltage drop regulator
      into single chip, therefore no external LDO required.

      page 14,
      >V5 47 23 P 5V-to-3.3V regulator Vin
      V33 48 24 P 5V-to-3.3V regulator Vout

      1. You are absolutely right, no LDO required, my wrong, I don’t remember where i got this information.

        However I clearly remember having heat issues, and this can be seen in the datasheets: the FE1.1s consumes 100 mA typ. for 1 HS up-stream / 4 HS down(streams, whereas the GL850G is 178 mA typ. That’s 0.9W vs. 0.5W, and this may explain why I had reliability issues with them. An SSOP28 package is typically 80°C/W, so @70°C, max. dissipation is 1.06W…

      2. Agreed on the heat issue. I looked at the FE1.1 part and they looks a lot more impressive too with the MTT. Too bad their SOP FE1.1S uses a single transactor. It is probably not a big deal these days and the prices are not too bad.

        Potentially if you instead use an external 3.3V LDO (1117 cost $0.04) to the GL850G, it could remove quite a bit of that heat from the package. The chip have separate pin for the 3.3V in and 3.3V regulator output, so this is possible.

  6. Does anyone know where to get a Raspberry Pi Zero these days? I’ve been trying to get one for a long time, but no one seems to have it (not counting Ebay, i don’t wanna pay 25 dollars)…. I have tons of projects i look forward to but i really need a Zero for them…

    1. Most of the places that currently sell them either mark the price up or sell the zero as part of a ‘kit’ as a way to bring the price up. I’m waiting until after Christmas. Hopefully the zero ‘craze’ will calm down and the board will be available to be purchased for $5 from most electronics parts outlet

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