VOISS HowTo - Components

Written by Rich Morin.

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Precis:  what's included in a VOISS system

Note: As of early 2020, the VOISS project and F123Light were discontinued. For details, see VOISS - Status.

The VOISS - Introduction page describes the motivation, design, and components of the VOISS Classic system. This page is part one of a HowTo for putting together a similar system. It provides links to background information, covers component selection, etc. As usual, please let me know about any errors or omissions!

Base Hardware

The system’s components are mostly commodity items. You may have some of them on hand; if not, you can get them quite easily. I’ll provide Amazon links, but clearly you are free to shop elsewhere, find alternatives, etc.

Processor Board

Get the Raspberry Pi 3 Model B+ (aka 3B+) computer, as used in the VOISS Classic models. This will ensure that you’re using the same hardware platform that the development team is targeting, so there is less chance of incompatibilities. Also, the 3B+ design is expected to be stable and supported for several years. Here are some quotes from the Raspberry Pi Foundation’s product web page:

The 3B+ is a “full-size” Raspberry Pi model, so it has lots of convenient interfaces (e.g., audio jack, USB sockets). Nonetheless, it uses relatively little power, making it a good choice for a portable system where battery life is a consideration. The performance should be just fine for most normal interactive use.

Data Storage

Like most computers, the 3B+ uses two basic kinds of computer data storage. One is transient; the other provides long-term storage. The following notes only provide a quick overview; for more details, see the VOISS - Storage page.

The 3B+ uses 1 GB of Random Access Memory (RAM) for its transient data storage. This is a fixed limit: the RAM is built into the processor chip, which is soldered onto the circuit board. Although virtual memory lets the computer pretend it has up to a few GB of RAM, this can bring the computer to a crawl if pushed too far. Fortunately, the available memory should be enough for most use cases.

When data isn’t actively needed by the processor, it should go into long-term storage. The default form of this, on the 3B+, is the microSD card. However, you can also store data on a USB-connected device, such as a USB flash drive. Plugging in one (or more!) of these is a lot less effort than swapping out the microSD card.

The microSD card is an amazing triumph of technology. It’s about the size of a fingernail and the current generation of cards can store up to 1 TB of data (e.g., images, music, software, videos). This is far more than most users will ever need, so pick a size that meets your budget and expected needs. If you’re planning to add a bunch of data or software, get more storage than you think you’ll need.

One reason for this is that you really won’t want to change these cards very often. Aside from taking time and effort to copy, handling these cards can be a real challenge (even for sighted and reasonably dextrous geezers such as me). Having a card slip out of your fingers and fall on the floor could be anything from a nuisance to a disaster, depending on its contents, your luck, and your capabilities.

So, getting a card that you don’t expect to replace seems like a reasonable precaution. The maximum capacity offered on the VOISS Classic is 128 GB; this Samsung card provides that amount of storage for only $20. I’d also get some flash drives (at about the same price) to use for backups, file transfers, etc. Here’s one that is nice and compact…

Note: Be cautious of Awesome Deals on off-brand storage devices. Your bargain device may not function at all, let alone provide all the promised storage. It might also fail unexpectedly, taking away piles of your valuable content. My recommendation is thus to go with a name-brand product from a vendor who will make good on any problems.

CPU Enclosure

It isn’t strictly necessary to enclose the processor board, but it’s definitely a Good Idea. After all, the board has a number of tiny and fragile components, sharp edges, etc. That said, you should think about what kind of enclosure to get.

Even if you think you’ll never want to hack around with hardware, I’d suggest getting an enclosure that provides convenient access to the computer’s GPIO pins, video interfaces, etc. The official Pi 3 case from the Raspberry Pi Foundation does all of this. Although it can fully enclose the computer, it also has removable panels on the top and both sides.

External Interfaces

Note: You may want to use other external interfaces in preference to the default approaches. That’s fine, but I recommend that you begin with the default interfaces. Once your system is working reliably with these, you can try swapping in devices that use alternative interfaces. That way, if you can’t get the new device to work, you can always get back to a working setup.

The “full-size” RasPi models support an amazing range of external interfaces. The VOISS - Interfaces page provides quick summaries of the most popular ones, with the usual links for more detailed information.

External Devices

Now that we’ve touched on the topic of external interfaces, we can talk about the devices that you would normally use with them.

Headphones

The 3B+ has an 1/8” (3.5 mm) phone jack, providing stereo audio output. VOISS provides a lightweight pair of headphones to use with this jack. Depending on your preferences and usage modes, you may prefer to get fancier (e.g., noise cancelling) headphones or a pair of earbuds. Here are some economical options, to get you started.

Keyboard

VOISS provides a full-size, PC-style, USB keyboard with function keys, a numeric keypad, and so forth. This is a great choice for a home or office environment, but its weight and bulk may make it awkward for you to carry around. So, I’d recommend getting a smaller and lighter keyboard for portable use. Anyway, here are some economical options, to get you started:

USB Power

The 3B+ is powered by means of a micro-B USB socket. Like the microSD card, the plug is rather tiny, so it can be difficult to insert. Fortunately, because it’s on the end of a cable, it can’t get lost! Still, you may want to leave that end of the cable plugged into the 3B+, to avoid having to deal with it every time you want to power up the system.

The VOISS Classic includes a USB power bank. This is a decision which I emphatically endorse. Being able to use the VOISS anywhere you like (e.g., sitting on a park bench) is pretty awesome, but that’s just part of the story.

Even if you only expect to use the VOISS in a location with generally reliable and easily available power, I’d recommend running your power feed through a power bank. For one thing, this provides your computer with an uninterruptable power supply. So, it can keep working during transient power outages. Like when someone (oops!) unplugs your power supply…

There’s a lot to be said about power banks and power supplies, so I’ve written up an overview page on the topic. However, the gist of it is that you’ll want to have devices that can supply a close approximation of 2.5 Amperes to the 3B+. Also, get a big enough power bank to keep your system running for a while.

Miscellanea

You’ll also need a way to carry and deploy your system, as well as some cables to hook things together.

Carrying Case

The VOISS Classic’s “pouch” looks very convenient for a portable system. It holds all of the components in place, so they won’t get unplugged, etc. It can be unzipped for use and closed back up when you’re done. Unfortunately, its design is optimized for the keyboard they chose, so VOISS has no current plans to sell it separately.

Don’t despair, however; you probably have something around that will serve. I suspect that a small briefcase would work pretty well. I’d use hook and loop fastening tape (e.g., Velcro) to mount the power bank and computer to the bottom. (Be sure to leave room to plug and unplug the cables!) The remaining components (e.g., headphones, keyboard, wall wart) can be pulled out for use and stuffed back into the case for transport.

Note: The 3B+ doesn’t produce much heat, but it can still overheat if operated in a totally enclosed container. So, for example, if you have it mounted inside a briefcase, be sure to leave the lid open!

Cabling

You’ll need several USB cables to hook things together. One will go from the power bank to the processor board. Another may go from a power supply (aka wall wart) to the power bank. Finally, you may want to add audio or USB peripherals (e.g., braille display, headphones, keyboard, mouse) or even Ethernet.

Fortunately, computer cables are really cheap on eBay. So, get a variety and find out which one(s) work best for what purposes. A lightweight extension cord or “triple tap” can also be useful if you need to share a crowded wall outlet when you charge up your power bank. A 3.5 mm (1/8”) stereo audio cable or a twisted-pair Ethernet cable can also be useful on occasions.

Playing with Hardware Attached on Top (HAT) boards can be a hassle, because the RasPi case tends to get in the way. So, the most convenient approach might be to get the Pimoroni Mini Black Hat Hack3r ($20). This kit includes an adaptor board which can host a HAT, a pHAT used by the Pi Zero), or “pin wires”. It also has a short, 40-pin cable, rubber feet, etc.

Moving On

At this point, you should have a good idea of what hardware components go into a VOISS system, what they are supposed to do, and how to obtain them. In Part 2, we’ll put the components together, load up some software, and (try to) bring up a running system.