Yoctopuce YoctoHub-Shield User manual

YoctoHub-Shield
User's Guide

www.yoctopuce.com iii
Table of contents
1. Introduction 1...............................................................................................................................
2. Presentation 3..............................................................................................................................
3. Connections 5..............................................................................................................................
4. Assembly 7....................................................................................................................................
5. Characteristics 9........................................................................................................................

iv www.yoctopuce.com

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1. Introduction
The YoctoHub-Shield is a 50x58mm electronic module enabling you to add 4 ports to a YoctoHub-
Ethernet or to a YoctoHub-Wireless. You can cascade several of these YoctoHub-Shields on the
same hub. As all Yoctopuce products, the YoctoHub-Shield is plug-and-play: you only need to
connect it to a hub for its ports to start working immediately. No configuration is required.
The YoctoHub-Shield
The YoctoHub-Shield is not a USB hub. While using micro-USB type connectors, its down ports use
a proprietary protocol, simpler than USB. Therefore, you cannot drive, or even power, USB devices
other than Yoctopuce modules.
Yoctopuce thanks you for buying this YoctoHub-Shield and sincerely hopes that you will be satisfied
with it. The Yoctopuce engineers have put a large amount of effort to ensure that your YoctoHub-
Shield is easy to install anywhere and easy to drive in all circumstances. If you are nevertheless
disappointed with this module, do not hesitate to contact Yoctopuce support1.
1 [email protected]

2 www.yoctopuce.com

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2. Presentation
1: Yocto-led 5: Port 1
2: Yocto-button 6: Port 2
3: Debugging port 7: Port 3
4: Trunk bus connectors 8: Port 4
Yocto-button
The Yocto-button has two functionalities. First, it can activate the Yocto-beacon mode (see below
under Yocto-led). Second, if you plug in a Yocto-module while keeping this button pressed, you can
then reprogram its firmware with a new version. Note that there is a simpler UI-based method to
update the firmware, but this one works even in case of severely damaged firmware.
Yocto-led
Normally, the Yocto-led is used to indicate that the module is working smoothly. The Yocto-led then
emits a low blue light which varies slowly, mimicking breathing. The Yocto-led stops breathing when
the module is not communicating any more, as for instance when powered by a USB hub which is
disconnected from any active computer.

2. Presentation
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When you press the Yocto-button, the Yocto-led switches to Yocto-beacon mode. It starts flashing
faster with a stronger light, in order to facilitate the localization of a module when you have several
identical ones. It is indeed possible to trigger off the Yocto-beacon by software, as it is possible to
detect by software that a Yocto-beacon is on.
The Yocto-led has a third functionality, which is less pleasant: when the internal software which
controls the module encounters a fatal error, the Yocto-led starts emitting an SOS in morse 1. If this
happens, unplug and re-plug the module. If it happens again, check that the module contains the
latest version of the firmware, and, if it is the case, contact Yoctopuce support2.
Trunk bus connector
The trunk bus connector is used to connect the YoctoHub-Shield to the master hub and to chain
shields. It is based on 10 pole Picoflex connectors.
Debugging connector
This connector enables you to access the YoctoHub-Shield directly by USB with the appropriate
cable. It behaves exactly like any other Yoctopuce module. Because using the YoctoHub-Shield is
totally transparent, you most likely will never need to use this debugging port.
Down ports
You can connect up to four Yoctopuce modules on these ports. They are then available as if they
were connected directly to the master YoctoHub. Beware, the protocol used between the YoctoHub-
Shield and the Yoctopuce modules is not USB, but a lighter proprietary protocol. Therefore, the
YoctoHub-Shield cannot manage devices other than Yoctopuce modules. In particular, you cannot
add ports to a YoctoHub-Shield by using a standard USB hub3.
Warning: the YoctoHub-Shield USB connectors are simply soldered in surface and can be pulled out
if the USB plug acts as a lever. In this case, if the tracks stayed in position, the connector can be
soldered back with a good iron, using flux to avoid bridges. Alternatively, you can solder a USB cable
directly in the 1.27mm-spaced holes near the connector.
1 short-short-short long-long-long short-short-short
2 [email protected]
3 The Micro-USB-Hub made by Yoctopuce is a standard USB hub and does not work with the YoctoHub-Shield.

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3. Connections
The YoctoHub-Shield is designed to be connected to a master YoctoHub with the provided cable. It
is a simple ribbon cable with a 10 pole Picoflex connector at each end.
A YoctoHub-Shield connected to a YoctoHub
The cable provided with the YoctoHub-Shield is very short on purpose. The bus linking all the shields
with the master YoctoHub must be as short as possible in order to maintain high quality
communications. We recommend that you keep the distance between the master YoctoHub and the
most remote YoctoHub-Shield under 75cm. Keep this in mind if you decide to move the YoctoHub-
Shield away using your own cables.
Theoretically, you can chain up to 10 YoctoHub-Shields, which makes a total of 43 Yoctopuce
modules connected to the same hub. However, the total current a YoctoHub can provide being
limited to 2A. Therefore, depending what devices you use, that limit might be reached before you
have connected 43 modules. Moreover, the more connected modules you have, the more the whole
risks to slow down because of saturation of the bus (especially if you use modules that share a lot of
data). Note that you can control each port independently. You can thus optimize power consumption
and bandwidth by shutting off the modules that you do not need.

3. Connections
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You can chain several YoctoHub-Shields.
You do not need to put the YoctoHub at the end of the chain. Note, however, that the YoctoHub-
Wireless has a small design flaw: a tiny capacitor prevents you from pushing down completely the
Picoflex connector on one of the headers. Use the other header or take a cutter to notch the ribbon
cable connector.
Since the YoctoHub-Shield allows to build huge stacks of devices, it's tempting to have several
projects running at the same time on the same shield stack. However, a Yoctopuce hub is able to
manage only 8 connections in parallel. An application using the Yoctopuce API to access a hub
needs 2 connections, the first one for the set/get functions, and the second one to manage callbacks
and plug-and-play events. Therefore, you can have up to 4 applications talking to a hub at the same
time. Trying with more will cause a many connection errors. The VirtualHub counts as one
application.