UUGear BIG7 User manual

Copyright © 2018 UUGear s.r.o. All rights reserved.
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........................................................................................ 6
Bus-Power Mode......................................................................................... 6
Self-Power Mode......................................................................................... 7
About MTT and STT........................................................................................... 7
Usage Guide...................................................................................................... 8
Raspberry Pi Model A and B ....................................................................... 8
Raspberry Pi B+, Raspberry Pi 2 and Raspberry Pi 3 (B Model)................11
Raspberry Pi A+........................................................................................ 17
Raspberry Pi Compute Module (with Development Kit)............................. 19
Raspberry Pi Zero..................................................................................... 21
Monitoring USB Port Usage ............................................................................. 23
Controlling the Power for USB Ports ................................................................ 24
Integrates with Witty Pi 2.................................................................................. 26
Integrates with Zero2Go................................................................................... 30

1
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). The old Raspberry Pi A and B model also have the same size, except that
they don’t have those rounded corners. This USB hub has 6 mounting holes at correct
positions and could be mounted under any Raspberry Pi model except the compute
module.
If you are using this USB hub on Raspberry Pi B+ or Raspberry Pi 2/3 (B model), you
can make use of all the 4 pogo pins to make power and USB data connection without
any USB cable!

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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
Bluetooth
Adapter
Arduino Board
USB Logic
Analyzer
USB Camera
You may not want to connect all of them at a time. The point is that sometimes you
may need more than 4 USB ports. As for the A/B/A+/Zero model and the compute
module with development kit, they have only one or two USB ports and will need a
USB hub when you want to connect more than one USB devices to them.
For different models of Raspberry Pi, this USB hub uses different approaches to
(optionally) back-power the Raspberry Pi, which significantly simplifies your wiring
and allows you to power both the USB hub and Raspberry Pi with only one power
supply.
The unpopulated 5x2 pin header could be used to connect external LEDs for
indicating the port usage state. Or connect to micro controller for detecting the port’s
state.

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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

4
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
M2.5 nuts x 4

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Specifications
Dimension:
85mm x 56mm x 10mm
Weight
28g (net weight without any accessory)
Standards
USB Specification Revision 2.0 and 1.1 compatibility
Multiple Transaction Translator (MTT)
Data Speed
USB v1.1: up to 12 Mbps
USB v2.0: up to 480 Mbps
USB Ports
Upstream: 1 (mini-USB)
Downstream: 7 (A-type USB)
LED Indicators
Power: 1 (red)
Port Activity: 7 (green or yellow)
Power Mode
Bus-Power / Self-Power
Output Voltage
DC 5V
Output Current
Bus-Power: maximum 500mAfor all ports
Self-Power: maximum 3A for all ports
Static Current
4mA
Operating Temperature
0℃~70℃
Storage Temperature
-20℃~60℃
Humidity
0~80%RH, no condensing

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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. So if you choose
back-powering, make sure you only connect one power supply to the USB hub, and
do not connect any power supply to the micro USB port on Raspberry Pi.
Some models of Raspberry Pi allow back-powering via the USB port, but some do not.
There are two pogo pins in the package and they could be used to back-power
Raspberry Pi via the 40-pin GPIO header, when back-powering via USB is not
supported by Raspberry Pi.
About Powering Mode
A USB hub could be powered by the USB bus (bus-power mode), or be powered by
the power supply (self-power mode). Bus-power mode is simpler as it does not need
to have external power supply, but it has quite limited ability to power the devices on
the USB hub. When you are trying to power more devices with higher current, it is
recommended to use the self-power mode.
This USB hub supports both bus-power mode and self-power mode.
Bus-Power Mode
If you only connect USB devices that consume very small current to the USB hub, you
can consider using the bus-power mode. Just make sure the jumper is at “power link”
position (which is the default setting) and do not connect power supply to the USB
hub.
When you use a USB - miniUSB cable to connect a USB port on Raspberry Pi and the
upstream USB port on the USB hub, the USB hub will be powered too (taking power
from the USB bus). In this case, the USB hub is working in bus-power mode, and the
maximum output current for all ports are 500mA, according to the USB standard.
Remarks: If you are using the first revision of Raspberry Pi A/B, each USB port on it
has a 140mApolyfuse, which will reduce the maximum output current to about 100mA.
In this case, it is strongly recommended to use the self-power mode instead.

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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.
About MTT and STT
A USB hub may have two possible ways for organizing Transaction Translators (TTs).
A USB hub could have one TT for all downstream ports that have USB devices
attached (which is called Single Transaction Translator, STT), or the USB hub could
have one TT for each downstream port (which is called Multiple Transaction
Translator, MTT) .
For Single Transaction Translator (STT), connecting one USB 1.1 device to the hub
will force all ports to process data with USB 1.1 standard, thus slowing down all USB
devices on the same USB hub. While for Multiple Transaction Translator (MTT), each
downstream port has its own transaction translator to provide the best USB
performance no matter what class of USB device is connected.
So MTT is better than STT, if the higher price is acceptable.
This USB hub has Multiple Transaction Translator (MTT).

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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 (Aand 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.
The mounting is very straightforward, just put the USB hub under Raspberry Pi and
place the copper standoffs between the USB hub and Raspberry Pi (align to the
mounting holes), and tighten the two ends of standoff with screw and nut. Our
suggestion is to put the screws at the bottom of the USB hub and put the nuts on the
top surface of the Raspberry Pi board.
Use the USB - mini USB cable to connect the USB port on Raspberry Pi and the mini
USB port on the USB hub and then it will be ready to work.
By default the jumper is at the “power link” position, and it can back-power your
Raspberry Pi. When the power supply is connected to the USB hub, you will see your
Raspberry Pi is getting powered too. This allows you to use only one power supply to

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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.
After putting the USB hub under Raspberry Pi, you can place the copper standoffs
between the USB hub and Raspberry Pi (align to the 4 mounting holes). By tightening
the two ends of echo standoff with screw and nut, the USB hub will be firmly mounted
under your Raspberry Pi. Our suggestion is to put the screws at the bottom of the
USB hub and put the nuts on the top surface of the Raspberry Pi board, you can
reverse it though.
Raspberry Pi B+ and Raspberry Pi 2/3 (B model) do not support back-powering via
USB port. However, you can use two pogo pins (included in the package) to let the
USB hub to back-power your Raspberry Pi via the (bottom of) 40-pin header.
What’s more, you can use another two pogo pins to make the USB data connection
(D+ and D-). As a result, your USB hub doesn’t need a USB cable to work with your
Raspberry Pi!

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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.

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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. Fix the 4 standoffs under Raspberry Pi with the nuts.
2. Align the D+ and D- pogo pins to the 2 joint points under USB port.

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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.
Remarks: don’t let the pogo pin touches any other pin in the header, or it might
damage your Raspberry Pi!

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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. After doing so, you will need two power supplies, one for the USB hub and
the other for Raspberry Pi. You will need a mini-USB cable for connecting the USB
hub to your Raspberry Pi. Also the jumper should be placed to the opposite side
against “power link”.

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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. Just make sure to
place the jumper to “power link” position and only connect a power supply to the USB
hub, then Raspberry Pi A+ can be back-powered by the USB hub.
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 Raspberry Pi accordingly.

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