BIG7 USB Hub (Rev 2) for Raspberry Pi User Manual Copyright © 2018 UUGear s.r.o. All rights reserved.
Table of Content Product Overview ............................................................................................... 1 Package Content................................................................................................ 4 Specifications ..................................................................................................... 5 About Back-Power (Back Feeding Power).......................................................... 6 About Powering Mode .............................
Product Overview This is a 7-Port USB hub designed for Raspberry Pi. It extends one USB port on Raspberry Pi to 7 usable USB ports, which allows you to connect much more USB devices to your Raspberry Pi. This USB hub is compatible with all versions of Raspberry Pi, including the old A/B model, A+/B+ model, compute module (with development kit), Raspberry Pi 2/3 (B model) and Raspberry Pi Zero. The board size of this USB hub is the same with Raspberry Pi B+ or Raspberry Pi 2/3 (B model).
Raspberry Pi B+ and Raspberry Pi 2/3 (B model) have 4 USB ports on board, which are usually enough for your project. However, sometimes you may need more USB ports. Below are some USB devices you may want to connect to your Raspberry Pi: Keyboard Mouse Wi-Fi Dongle 3G Dongle Flash Drive Portable Hard Disk USB Audio Card SD Card Reader Arduino Board USB Logic Analyzer USB Camera Bluetooth Adapter You may not want to connect all of them at a time.
The figure below shows how the USB hub looks like: 1~7) Downstream USB port with green (or yellow) LED as activity indicator 8) Upstream USB port 9) Power link jumper 10) Micro-USB DC 5V power in 11) Red LED as power indicator 12) Alternative DC 5V power in 13) Pogo pin holder (+5V) 14) Pogo pin holder (GND) 15) Unpopulated 5x2 header for port state indication 16) Pogo pin holders (D+ and D-) 17) Unpopulated 2-pin header for turning on/off USB ports’ power 3
Package Content Each package of this USB hub contains: 7-port USB hub board x 1 Cupped head pogo pin x 4 M2.5 x 10+6mm Copper Standoff x 4 M2.5 screws x 4 M2.
Specifications Dimension: 85mm x 56mm x 10mm Weight 28g (net weight without any accessory) USB Specification Revision 2.0 and 1.1 compatibility Standards Multiple Transaction Translator (MTT) USB v1.1: up to 12 Mbps Data Speed USB v2.
About Back-Power (Back Feeding Power) Back-power (or back feeding power) here means the USB hub provides electronic power to Raspberry Pi. This can only (optionally) happen when the USB hub gets power supply connected (works in self-power mode). The advantage of back-power is that you only need one power supply to power both the USB hub and Raspberry Pi. Someone may not like the back-power, but it actually works without problem unless you connect two power supplies and let them fight with each other.
Self-Power Mode If you connect the power supply to the micro USB port (power in) on the USB hub, the USB hub will work in self-power mode, or say it becomes a powered USB hub. In this case the maximum output current for all USB ports are 2,600mA. If the USB hub is also back-powering your Raspberry Pi, the current consumed by Raspberry Pi is also taken into account. For example, if Raspberry Pi consumes 260mA, then the maximum output current for all USB ports will become 2,340mA.
Usage Guide This USB hub can work with all models of Raspberry Pi. However, the mounting and wiring may be different for various models. Please read the sections below for details. Raspberry Pi Model A and B The old models of Raspberry Pi (A and B model) only have two mounting holes, so we only need two sets of copper standoff, screw and nut to mount the USB hub under it. The pogo pins should not be used in this case.
power both the USB hub and your Raspberry Pi. If you don’t want the back-powering, you can disable it by putting the jumper on another side. By doing so, you will need two power supplies, one for the USB hub and the other one for your Raspberry Pi.
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Raspberry Pi B+, Raspberry Pi 2 and Raspberry Pi 3 (B Model) Raspberry Pi B+ and Raspberry Pi 2/3 (B model) have four mounting holes on board, so we can use the four sets of copper standoff, screw and nut to mount the USB hub under it. Two pogo pins could be used to back-power your Raspberry Pi, while the other two pogo pins could be used to make the USB data connection, so your USB hub can work without a USB cable.
There are 4 pogo pin holders on the USB hub board. Gently put the pogo pin into the holder and press it to the bottom. You can use the other end of the tweezers.
The cupped head of the pogo pin should be on top. When you mount the USB hub under Raspberry Pi. The cupped head will contact to the +5V and GND pins in the 40-pin header. Also the cupped head will contact to the D+ and D- at the bottom of a USB port on Raspberry Pi. Although the pogo pin has cupped head, which is helpful for aligning to the joint point, it is still a challenge to align 4 of them a time. We found that following the steps below could make things easier: 1.
3. Align the GND pogo pin to the most left-bottom pin (GND) in 40-pin header. 4. Align the +5V pogo pin to the most right-top pin (+5V) in 40-pin header. 5. Use screws to fix the USB hub under Raspberry Pi.
In the figure above you can see the actual position of the D+ and D- joint points. After mounting the USB hub under Raspberry Pi, one USB port on Raspberry Pi is taken by the USB hub (as upstream port) and it could not be used by other USB devices. Thanks to the 4 pogo pins, now your Raspberry Pi has 10 usable USB ports without connecting any USB cable! If you don’t want to use the back-powering, just take out the pogo pins from their holders.
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Raspberry Pi A+ Raspberry Pi A+ has the same mounting holes with B+ model, so the process to mount the USB hub under it will be quite similar. The A+ model has its only USB port on different position, so we could not make the USB data connection with pogo pins, and a USB cable will be necessary to finish the connection. Different than the B+ model, Raspberry Pi A+ supports back-powering via USB port. So it is not necessary to use those pogo pins for back-powering.
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Raspberry Pi Compute Module (with Development Kit) The Raspberry Pi compute module is supposed to be inserted into another product and it doesn’t have any USB port on its board. However if you are developing a product that uses Raspberry Pi compute module, you should also have a development kit, which allows you to plug the compute module on a development board and access the USB port on it.
If you don’t want the back-powering, just put the jumper to the other side and connect two power supplies to USB hub and the development board accordingly.
Raspberry Pi Zero Raspberry Pi Zero has 4 mounting holes, but only two of them could be used to mount the USB hub under it. Raspberry Pi Zero supports back-powering via the data USB port, so you can just put the jumper to “Power Link” position and connect power supply to the USB hub. To connect the upstream USB port to Raspberry Pi Zero’s data USB port, you will need a USB - OTG adapter (not included in the package).
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Monitoring USB Port Usage There is a footprint for 5x2 header (P4) on the USB hub board. This header is not populated and it is reserved for users who wants to monitor the USB port usage remotely. The figure below shows the naming of each pin within this header: LED5 LED6 LED7 GND DRV LED1 LED2 LED3 LED4 3.3V You can make use of these pins to build your own USB port usage monitor.
Controlling the Power for USB Ports Since revision 2, BIG7 USB hub has a new footprint for 2-pin header (P7) on the top-right corner of the board. This header is not populated and it is reserved for users who wants to control the power for USB port with software or external switch. The ENABLE pin is pulled up (to 3.3V) by default. The power of USB ports will be cut when the ENABLE pin is shorted to the GND (ground) pin.
Usually the USB devices will get back to work after the power is resumed. However, sometime the USB hub may need a reset to make sure all connected USB devices will work properly. You can follow this tutorial to compile a very small program to reset the USB hub. By resetting the BIG7 USB hub, all USB devices that connected to the USB hub will be reset as well. In order to get the device ID for the BIG7 USB hub, you can run “lsusb –t” command: pi@raspberrypi:~ $ lsusb -t /: Bus 01.
Integrates with Witty Pi 2 Witty Pi 2 is another UUGear product, which is a small extension board that can add realtime clock and power management to Raspberry Pi. It can be mounted above Raspberry Pi by connecting to the 40-pin GPIO header. Since this USB hub can be mounted under Raspberry Pi, it has no conflict with Witty Pi 2. Instead it can be easily integrated into the Witty Pi 2 + Raspberry Pi combination and become a nice sandwich structure.
The integration is quite simple, just mount Witty Pi 2 over Raspberry Pi and mount the USB hub under Raspberry Pi, you can do either part first. The Witty Pi comes with 4 female-female standoffs, while the USB hub comes with 4 female-male standoffs, thus they could be connected together and has Raspberry Pi board in the middle. Since Witty Pi 2 is the power manager, it should be the only one that gets connected to the power supply.
to use the USB cable. Raspberry Pi A+ doesn’t need to use the pogo pins for back-powering Raspberry Pi, but the situation changes when integrating with Witty Pi. The pogo pins will also be used to make sure the USB hub can work in self-power mode, otherwise the USB hub can only pull power via the upstream USB port, which can only provided very limited current. For Raspberry Pi A, B and compute module with development kit, Witty Pi 2 could not be mounted on them because of the incompatible GPIO pin header.
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Integrates with Zero2Go Zero2Go is another UUGear product, which accepts 5~26V DC input and output 5V to power your Raspberry Pi. It can be mounted above Raspberry Pi by connecting to the 40-pin GPIO header. Similar with Witty Pi 2, Zero2Go has no conflict with BIG7 USB hub, and can be easily integrated together.
