Low Power, Cheap ARM Lab Enclosure (DIY)

This project was born from the need to have a low-cost, replicable and accessible laboratory for a general public that works with information systems or for any other purpose that is desired.

Project inspiration

So that you can understand how we got to this solution, I will tell you about some of the problems that I experience as a computer scientist.

I think that for a person who makes a living from computing it is normal to have a work computer with good hardware characteristics, however there are times when we forget that resources are finite.

When working with different projects it is normal to have several folders with work files and documentation or several virtual machines to carry out tests and out of nowhere you realize that you have 3 or 5 virtual machines running at the same time and that you start to take notes. that your computer is getting stuck when google chrome was in charge of eating the last memory resources that your machine had left.

That's when you notice how a work team is transformed from nothing into a server with a keyboard and screen that operates the entire working day, while you listen to music and have one or another batch process running to do a work activity.

That's when I questioned if my work team was really a work team and not a server like the one Elon Musk works at x.com at night.

And I decided to think of solutions to get away from my work computer certain processes that were not necessary for them to be running on my local computer.

The truth is that when you work for companies it is normal to see that they invest in servers for certain operations, but in our case (we are not companies) we always end up using our own work equipment as a server.

For my part, I did not intend to invest more money in buying a larger computer unit that looks like a dryer due to the emission of heat and noise, in addition to the electrical consumption that it entails, nor did I want to build equipment in the cloud with information that I consider sensitive that could be exposed, to only alleviate the operations carried out by my work team.

Thinking about what I could do to solve this dilemma, inspiration struck me when I saw a small SBC Orange Pi Zero gathering dust on my desk and said: “The answer was always in front of me”.

And the answer was that little SBC, so I decided to dust it off and said “Today is your big day to debut!”

In a few words, she had idle hardware that she was not using and that was of very low consumption and more new ideas came to her head, so I decided to capture her as objectives:

• Set up a mini computer center
• Based on ARM architecture
• Low electrical consumption (amperage)
• 5V network
• Simple
• Compact, reduced space
• Portable and lightweight (simple to transport anywhere)
• Modular
• Plug and Play
• Cheap
• Harmonically visual
• Replicable

Already with a much clearer vision, visualize that the base of this technology is focused on adding components that can work in a 5V electrical network with low amperage.

And that was the beginning of this adventure!

Technical Limitations

When working with technologies it's normal to try to push solutions to the limits, but each piece of hardware was designed to work with certain limits, such as the USB 2.0 bus versions with a data transfer rate of 480 Mbps, or the interface of fast ethernet network with a transfer speed of 100 Mbps.

That is why it is important to know the technical characteristics of the hardware with which we work and the bottlenecks that can be generated between the interconnection of the different points so as not to generate false expectations of high-performance operation. (Not to say that you can't emulate high performance with basic hardware, but techniques like clustering or distributed processing may need to be used if you want to achieve this with multiple devices)

Purpose of the project

The project has 4 pillars as its purpose:

• Set up economic technological infrastructure with low energy costs
• Installation of self-hosted applications that can provide 24x7 services
• Software testing laboratory
• Technical investigations of the solution

• 1 - 3D Printer
• 1 - PLA / PETG / ABS filament, 500 grs (ideally ABS)
• 1~7- Orange Pi Zero
• 1~7 - MicroSD (Class 10)
• 1~7 - Copper Heatsink Set
• 4~28 - M2.5 10mm Allen Countersunk Screws
• 1 - Ethernet Switch (Diewu Brand)
• 1 - 5 Port USB Power Supply (Orico Brand)
• 1~7 - cat5 Ethernet cables - 10cm
• 1~8 - USB Switches
• 1~7 - 2A Micro USB Cable - 15cm / 20cm
• 1 - USB 2.0 type A male DC 5.5mm/2.1mm cable - 20 cm (for switch)

Several of the materials have been added in a variable way (they have the character ~) since depending on the SBC that you decide to implement, they will be the materials to use.

The reason for the selected technologies was the good experience I had when setting up my first laboratory with an SBC (Single Board Computer) called Orange Pi Zero, where one of the things that amazed me was how this board has low energy consumption and that I could feed it from a 5v 1A cell phone charger, where we implemented a hybrid version that connects to 18650 lithium batteries recharged by 5V 2A solar panels.

In principle, this SBC with an ARM core helped me, together with a DTH22 sensor, to take humidity / temperature metrics of the part that was located, in addition to providing a wiki service with a mysql database engine, which worked 24 hours a day (arriving to have about 3 months of uptime without problems depending on factors such as the weather of the Autumn / Winter seasons or because the microSD card was corrupted in some sector).

With this experience gained from this mini project carried out several years ago and also that I already had several more boards bought before due to their relative low cost (compared to the value of the raspberry pi today), I thought that it would be a good solution to build an enclosure with several of these boards to have our own infrastructure and thus provide a local service from my home with the different computer systems that you need to work every day and that I could remove the virtual machines that provided service on my computer.

If you wanted to have more than one SBC on, you would need a power supply with a wide power capacity in Watts and that would have several 5v and 2A outputs since it is not so attractive to have a socket with all the sockets occupied with chargers. from cellphone. At the level of dimensions and functionality, an Orico brand charger caught my attention, which has a compact design and meets several of the needs I had in mind.

Once the charger was selected, it was time to think about connectivity, I thought it would not be so good to have several SBCs together and connect to Wi-Fi, there could already be a lot of intermittency or latency due to signal noise and the home router is already waging a war For quite some time with the cell phones of the family that connect to it, for which the best solution was to implement a switch, what interested me about the swtich was:

* That works with 5V and not more than 2A

* Metal casing (For better heat dissipation)

* Various ethernet interfaces

And we arrived at a switch with all those Diewu brand features that consumes 5V 1A and that was even Gigabit Ethernet (with the SBC I was not going to be able to take advantage of it because it is fast ethernet but it will help me to implement it with other generations of SBCs that have Gigabit Ethernet interface)

With the 5V switch, I could make use of one of the orico charger inputs and not have to use the transformer it comes with.

Since the Orico loader has 5 inputs there are 2 possible implementation scenarios

Scenario 1 - Connection of 4 SBC + Switch

Advantages

• It only occupies only 1 outlet
• By having fewer SBC, there is less heat emission by radiation to the other SBC.

Disadvantages

• Not all doors are occupied
• It may seem that 4 SBC is not that much processing power

Scenario 2 - Connection of 5 SBC and external connection of the Switch

Advantages

• 1 additional SBC is integrated to give more computing power
• More use is made of switch gates

Disadvantages

• It takes 2 power outlets, 1 for the charger and another for the switch transformer
• By having an SBC there is more heat emission by radiation to the other SBC

There could be a third or fourth scenario where 2 Orico 1 chargers could be added to each end to satisfy everything that has to do with energy issues, but there would be much more heat involved or you could also see chargers with a greater amount of USB or just look for a 5 port switch.

But for this experimental type project, these solutions were considered, depending on the computing capacity that is needed (4 vs 5 SBC).

Thinking about low energy consumption, it was decided to use a passive dissipation method with copper blocks since it has better heat transfer.

In fact, in the previous project the SBC was used without heatsinks and a high uptime was obtained. The decision to add heatsinks was made by:

• By having several SBCs together next to each other, the heat generated will be greater and it will be necessary to enter to dissipate
• The workload of the SBCs will be higher compared to the first laboratory project and it is expected that there will be more heat emission

The first thing I had to do was give the SBC a slight protection so that it is not so exposed to environmental conditions that it could damage them or to avoid damaging the board due to static, for this a thingiverse model was taken as a reference and it was made a remake to adapt them to our plates with heatsinks. In addition, this casing was added several outlets where air can enter or exit.

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Printing parameters:

Filament: PLA (Recomendable ABS)

Infill: 20%

Support: No

Brim: No

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Print time: 2 hours 15 minutes

Used material: 10 grs

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Other models were later generated for other versions of the SBCs.

You can download the STL files of the different designs of the casings according to the SBC you have from the following link:

Orange Pi Zero: https://www.thingiverse.com/thing:5849194

Orange Pi Zero Plus: https://www.thingiverse.com/thing:5877645

Orange Pi R1: https://www.thingiverse.com/thing:5891536

The screws to use were some that I had left over from the accessories of the 3D printers

Below I leave the measurements collected with the calliper.

If we compare the data collected from the screw with a technical sheet, I can deduce that it corresponds to a 10 mm M2.5 screw (I hope I'm not wrong)

So once the case is printed we must adjust the screws

I decided to print in different colors on the upper part of the case to quickly distinguish visually, the different versions of hardware that are handled

BLUE: Orange Pi Zero v1.4

YELLOW: Orange Pi Zero v1.5

GREEN: Orange Pi Zero Plus v1.1

WHITE: Orange Pi R1

Once the 3D printed case is assembled, you can now connect the microSD card with the Armbian operating system, depending on the versions you work with.

Now is the time to start uniting all the technologies into one, we proceed to take measurements of each device and the result is as follows:

Orange Pi Zero: 20m x 49mm x 50mm

Switch: 24mm x 153mm x 72mm

Power Charger: 28mm x 98mm x 70mm

Having clear the dimension of the different devices, different enclosures were elaborated to satisfy the need. You can download the enclosure design from the following link.

https://www.thingiverse.com/thing:5853872

Depending on the model you choose, the printing time will vary, which is quite long (up to 19 hours), so I recommend that you look for a good series while printing lasts.

In this section we will connect the ethernet cables and the power supply cables to the Orange Pi.

The solution of creating an enclosure has brought me several benefits, such as:

• Easy to transport from one place to another due to its portable design and small size
• low power consumption
• Replicable and scalable
• Aesthetic and harmonious design
• Privacy of your data

In addition to the experience gained on this occasion, we have a functional tool that works with me on a daily basis.

Along the way we have encountered problems such as:

• Heat dissipation (especially in summer season)
• Deformation of cases by heat (which were printed in PLA)
• Definition of policies and standards for administration of servers and applications

I know that many more improvements can be made such as:

• Add BMS and 18650 batteries
• Add SBC On/Off Front Switch Button
• Add fans to the enclosure for active heat dissipation via PID controls operated by ESP8266 or other technologies
• and a long etc.

It is worth mentioning that this is the beginning of something more interesting, that will be seen in new versions that are made and that it is not the definitive solution to all problems, the SBCs are more powerful every day at the computational level and It is a matter of knowing how to build new enclosures to the measurements of those more powerful SBCs and you could easily have an enclosure oriented towards clustering solutions such as Spark for data processing or a Kubernetes cluster with K3S and much more. of utilities depending on the need. (In fact we are already working on a new version with several improvements)

Most enclosures become just another accessory to the hardware, but it is necessary to give them the ability to be more intelligent and to support the hardware in daily operation.

This is the humble project that I built and wanted to share with you. I thank you for taking the time to read this article and I look forward to any feedback you can give me.

I hope you can enjoy it!

Greetings