An active USB hub for the Rasp Pi Zero

Lead Image © studiostoks,

A Nifty Extension

The Rasp Pi Zero comes with minimal equipment. To build it out, you will need an OTG adapter plus a USB hub. Makerspot has an interesting solution for this.

Frequently, the Rasp Pi Zero gets fitted out with more and more devices so that in the end the user requires a hub. At this point, the question becomes whether it makes sense to spend some more money and switch over to a better equipped, third-generation Rasp Pi with its four USB ports. Still, the Rasp Pi Zero has a very attractive price point. Moreover, it has a form factor that is undeniably more appealing than what the larger version can offer.

Unfortunately, a setup made from a Rasp Pi Zero, USB On-The-Go (OTG) cable and adapter, and a USB hub doesn't exactly look compact (Figure 1). This is where the hub from Makerspot [1] comes into play. All you have to do is attach it underneath the computer. The hub looks like a clone of a Kickstarter project [2] that you can get from merchants like eBay. The crowdfunding platform offers a number of other similar projects.

Figure 1: The Rasp Pi Zero's compact format gets increasingly diminished with the addition of devices like an OTG cable and a hub.

Innovative Connection

Figure 2 shows the hub with its four ports and the power connector on the left side. The double row of two pins each, in the middle, sits on springs and transmits current and data from below to the Rasp Pi Zero. There are corresponding counterparts on the Pi Zero.

Figure 2: The USB hub comes with four ports. You connect the drive to the Rasp Pi Zero via two pairs of pins.

The board layout for the Pi Zero has been changed slightly from revision 1.2 to 1.3 due to the new connection for the camera. Therefore, it is a good idea to be careful. The provider also carries a version for the old revision of the Pi Zero.

However, the connection only works reliably if you press the Rasp Pi Zero down strongly onto the hub. In other words, this hub has not been made for a quick connection. Instead, it is more like a permanent extension. Makerspot offers bundles with a suitable cover including screws and spacers. The construction transforms the Pi Zero into a miniature tower (Figure 3). Since the hub is docked underneath the Rasp Pi, all of the connections remain accessible (Figure 4).

Figure 3: This is a tower without the babble. The illustration shows the duo made out of the Pi Zero and hub.
Figure 4: The GPIOs on the Rasp Pi Zero continue to be accessible after the extra hub has been added.

There are no instructions for assembly. However, the project is intended for hobbyists, who should have no problem putting the setup together by referring to the figures. A cheap plastic has been used for the spacers and screws. Otherwise, this choice of material distracts from the solid impression that the hub makes.

The hub is powered either by the Rasp Pi Zero or by a cable plugged directly into an electrical outlet. If powered by cable, then the hub becomes the power supply for the computer. A fuse prevents too much current from flowing. The hub itself is limited to 2.4A. This should be sufficient for four standardized components and the Pi Zero. The variation with a two-fold path for current to the Rasp Pi and to the hub is actually possible, but it doesn't add any benefit.

In Operation

The hub is unremarkable during operation. The power requirements stand at 80mA, but the manufacturer is very precise about the specifications. As a result, the ports do not deliver enough current, for example, to start the power-hungry hard drive. These kinds of hard disks that come with Y cables should be phased out anyway. Devices like the Western Digital's PiDrive with 1TB capacity run easily, as did all of the other devices that were tested.

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