AmbaSat-1: a LoRaWAN Space Satellite Kit Assembly

Introduction

What is AmbaSat-1?

In this introduction we aim to provide you with a simple, watered down, run through of what the AmbaSat-1 is, how it works, and who it’s for. For more details, please check out our website:

www.ambasat.com

AmbaSat-1 is easy access Space exploration. With this open-source project we will provide access to example code which is easy to edit, or you can write your own if you're savvy enough and fancy more of a challenge. We primarily use the C/C++ programming language but the AmbaSat-1 is also compatible with Arduino. You may not be a coder, but for a first-time project it’s very accessible.

So what is a MK-II? The MK-II is an easily assembled kit form of the Ambasat-1 that is more approachable from a skill set point of view than AmbaSat's MK-I "Engineering Kit".

Aren’t Satellites Big? The Ambasat-1 is a ‘Sprite’ Class satellite, also known as a “Chip sat”; thanks to improvements made in semiconducting technology, we’ve turned the bulky technology of yesterday into the 35mm squared Sprite of today; and with a MK-II kit you can do this at home!

As for what you can do with it, this is YOUR satellite, it is purpose built and coded by you! We have a range of eight sensors. Feel free to be creative and surprise us with your ideas! The basic range of available sensors are:

1. Sensor 01: Humidity and Temperature

2. Sensor 02: Temperature

3. Sensor 03: Gas & Pressure

4. Sensor 04: Ambient Light

5. Sensor 05: TVOC

6. Sensor 06: UV

7. Sensor 07: CO2 emissions

8. Sensor 08: GPS (Earthbound only)

Or you can design, build, and program your own sensor, again if you're Tech savvy enough.

There are many practical applications for AmbaSat-1, especially for universities on a budget. The closest thing you'll find available on the market is a CubeSat but they are expensive and can take years to put together. With AmbaSat-1, you can be fully assembled and launched for the price of a PlayStation with assembly time lower than most game time experience! Also, AmbaSat-1 assembly time is less than the paying time of most games!

Do you want a satellite swarm to track climate change? With AmbaSat-1 you’ll have a fraction of the foot print of the current standard of satellite launches because up to 200 Ambasat-1 Sprite Satellites are launched into space on each rocket!

(An AmbaSat-1 MK-II Kit is needed which is available from the AmbaSat Website)

https://ambasat.com/shop/

Essential Tools:

● Soldering Iron or Station - A soldering iron is going to be your main and most reliable tool for mounting and connecting SMD (Surface Mounted Devices) and other components to your PCB. Soldering stations give much more control over the temperature of your iron, as well as often having a SMD Rework Airflow system built in.

● Solder - There’s no getting away from needing a decent solder, for this guide I’ll be using leaded solder.

● Tweezers (Metal or Ceramic) - Often handy for feeding solder into the right place, holding components in position or to give something a nudge in the right direction. Avoid Plastics.

● Snips or cutting pliers - useful for cutting your connection pins/material and trimming any wires used in the assembly.

● A Desktop or Laptop Computer- Needed for programming, testing and to receive satellite data from the AmbaSat Dashboard. Windows, Linux or Mac.

Recommended Software

● Visual Studio- Though also compatible with Arduino’s IDE (Integrated Development Environment) in this guide we will be using Microsoft’s IDE, download link follows: https://code.visualstudio.com/

Optional but Handy:

● Multimeter- a useful tool for measuring continuity, DC voltage and resistance. While not essential for assembly, it’s recommended to keep one to hand to identify any short circuits that may crop up during assembly. Also needed to test solar board voltage output once cells are fully connected.

● De-soldering tools- Such gizmos like spring loaded suckers, or material like copper solder wick can come in very handy, especially if you have no prior experience soldering. Soldering stations also can come with adjustable air flow re-work stations which can come in handy for removing damaged/misplaced components.

● Scalpel or sharp craft knife- always a handy thing to keep to hand.

● Anti-Static Soldering Mat/Grounding Band- When working with electrical components, it’s wise to ground yourself to help avoid accidently “Frying” any components with a static discharge. It’s in the optional section but we’d definitely recommend it.

Extra Materials (our personal suggestion)

● Blue Tack - Very useful material when it comes to space age technology

● Double Sided Tape - Helps to position your sensor before soldering

● Head Cleaner - Helps keep your soldering tip clean and prevents sticking

● Cuppa Tea - Borderline essential for cognitive function, especially for the British!

Though this is a fun and exciting project for anyone to undertake, this is far from a toy and must be respected. Where engineering is concerned, safety should always be considered no matter how experienced you are. If kids are involved, we would ask that an adult is present to observe and advise on the proper use of tools like a soldering Iron/station, hot air re-work tools and any sharp knives.

In this section, points of attention will be outlined in order to reduce the risk of injury and damage to yourself or your components.

What to Keep in Mind

STATIC! Yes, the components we are using here are sensitive to static charges and you should keep this in mind throughout the assembly process. Something as silly as wearing nylon socks on a cheap carpet could be enough to totally fry components on your PCB. What can we do to avoid this? Use an Anti-Static Soldering mat with a grounding band. With a band connected to something metal such as a desk leg, radiator, soldering station, or other... You can keep yourself grounded. This way you don’t have to worry about static while you work. Also transporting your components or your assembled satellite using protective packaging/wrappings is recommended; the red bubble wrap provided with your kit is excellent for this. If anti-static mats or bands are not accessible, be sure to firmly grab hold of something metal before you start tinkering in order to discharge yourself.

VENTILATION! Indeed, it can be easily overlooked especially if you have no prior experience with soldering. Inhaling solder fumes is not recommended! A well-ventilated space is suggested for all soldering, an open window at least if proper extraction fans are not available. If, like me, your personal hobby cave is not well ventilated, a soldering station with a smoker scrubber is highly recommended.

HOT! No touchy, touchy! Yes! Believe it or not, the tip and shaft of your soldering iron can get extremely hot, along with the components you are heating too. Keep this in mind if using a rework air flow station too. Always turn off equipment such as soldering irons Caution: Tea is also hot! If it isn’t, you’ll need a fresh one.

WATCH THAT CABLE! A surprisingly easy way to mess up your day, unless you’re using top end gear with silicone cables... your soldering iron can more than easily melt though your power cable’s insulation. Keep in mind, where you’re moving, placing, and resting your Iron to avoid this from happening.

Now that we have everything that we need, and we know what to keep an eye open for where health and safety is concerned, it’s time to pour a cuppa tea and prep your work area. What needs prepping?

1. Tea, keep tea out of spillage range of your work area, but close enough to be at hand if needed.

2. Let’s make sure you have a ventilated work space, open window if that’s your best option.

3. Turn on your soldering iron, it may take a moment or two to reach operating temperature; if using a soldering station, adjust your temperature to best suit your solder.

4. Wet your Soldering Iron’s sponge and/or make sure your Head Cleaner is close to hand (you don’t want to go hunting for these things mid task)

5. Place Tools you may need out and ready, having tweezers at the ready to tinker in a hot area, or handle something delicate saves time if you keep them to hand. Same for your snips and any desoldering tools you may have.

6. GROUND YOURSELF! Either attach your grounding band to your wrist, or make your best efforts to discharge any built up static before moving to the next point.

7. Lay out your components in front of you, your PCB Motherboard, the Sensor Board, antenna, Pins and other materials you feel you may need.

8. Have your computer close with compatible IDE software ready to go

Though Ambasat-1 is compatible with the Arduino IDE, for this guide we will be using Visual Studio Code. If you do not yet have this software please see the link below:

https://code.visualstudio.com

Ambasat-1 also uses the PlatformIO extension alongside Visual Studio; this is a professional tool for system and software developers that will work across many platforms. It can be installed from Visual Studio Code directly by searching for “PlatformIO IDE” in the search bar found on the left of the window. Once the extension is found, click on the green “Install” Button.

Now we’re on our way to having a usable IDE, you’ll just need the AmbaSat-1 definition file and the most up to date source code.

The definition file for the Ambasat-1 PCB holds the instructions for PlatformIO on how to configure your programmer gizmo. This file will need downloading from the following link:

http://ambasat.com/downloads/AmbaSat-1.json.zip

Once the Zip file is downloaded, unzip and copy the file “AmbaSat-1.json” to Platform IO’s boards folder. This location may differ across devices. The following locations are good places to check if the location isn’t obvious to you:

C:\Users.platformio\platforms\atmelavr\boards

C:\Users.platformio\boards

Good, now that is all set up and ready to go, let’s get hold of the most up to date source code for your satellite project. Because AmbaSat-1 is an open-source project, you can find all the code you’ll need and plenty of other interesting pieces of information from the AmbaSat GitHub Repository. Follow the link below and hit the green “Code” button and select “Download Zip”:

https://github.com/ambasat/AmbaSat-1

It’s important that this step is done before any testing of components. Why? When working with the AmbaSat-1 PCB, it’s crucial not to power the board without the antenna attached, otherwise your satellite may apply power beyond safe limits and potentially frying the chip. This would require replacement parts in order to get full functionality again.

The length of your antenna needs to be 91.5mm to suit the frequency of 915mHz; this is because of what’s known as the resonant frequency. If the cable is too short then not all of the signal will be transmitted but reflected back to your transmitter, damaging the transceiver. We provide one with a little extra length so please trim the antenna to the correct length.

Using your snips, sharp knife or even wire strippers (we recommend using a knife to avoid taking off too much insulation), remove a couple of millimetres or so of the insulation from one end of the antenna.

Taking care not to have the antenna protruding too far through this hole (if at all) on the motherboard (Circled in Blue in the above image), and make sure not to short these points here (Circled in Green above).

If any Points become shorted in the circled areas then this will stop your transceiver functioning. Shorts can sometimes be identified visually while other times with a multi-meter; they occur when you bridge two points that aren’t meant to connect, creating a short circuit that power flows through. If any points accidently become shorted by solder, heat up the solder till it starts to flow again, suck up the solder with your spring-loaded gizmo while it’s still flowing; you could also place copper wick over the solder and heat with the iron (with tweezers to hold the wick, it will get hot!).

Attach the antenna in place, either resting slightly into the hole near your transceiver or between the two points either side of this hole, connecting with solder. If needed, any protruding wire can be cut flush with snips. Be wary of keeping your iron connected to the antenna for too long, insulation will start to melt rather quickly.

Blue Tack or tape may be used to hold the antenna in position while soldering, be careful not to cold solder a weak connection as the antenna will break free. If struggling to get in place; add solder in place first using your iron, get your iron and antenna ready, reflow the solder with the iron and then place the antenna in place.

Once secured in the desired place, cut down to 91.5mm length. Give a slight but firm tug on the antenna; make sure it stays secure because there’s no fixing the loss of this once in orbit.

Done that? Good, let’s keep going!

Please note: If you’re AmbaSat-1 has a reserved slot onboard a rocket launch, we may replace your antenna prior to launch.

Now we have our antenna attached and at its proper length achieved, we can run power through the Ambasat-1 PCB. To do this we need to make use of our six programming pins. It’s worth keeping in mind that these pins are only temporary and will be removed prior to launch and before the solar board is finally attached, and so we advise to use light soldering in order to just ‘tack’ the pins in place.

The connection points on the left side of this image are the points of contact for the programming pins. (This is where I personally like to start using Blue-Tack to make a hi-tech sausage to help keep things in place during the soldering). Line up your six pins with the “GND”, “SS”, “VIN”, “RX”, “TX” & “DTR”.

As part of your Ambasat-1 Kit, you will be supplied with connection pins. These pins connect with the CH340 programmer to allow coding and testing as well as allowing your battery pack to connect to the assembled board for final testing. Again, keep in mind that these pins will need to be removed (which can be done by us here at AmbaSat once we receive your satellite prior to launch).

Once lined up, you’ll just want to tack these points lightly to your pins.

I like to start with the “GND” point and the “DTR” to help attach the pins neatly.

You can attach the pins in whatever order feels best for you, this is just the method I use to get the pins attached as neat as possible. Other methods are possible, and as long as the connection is made, the job will do. If too much solder is used, or you wish to remove these pins yourself after the final stages of coding & testing... then either copper wick, or a spring-loaded gizmo sucker can be used. An airflow tool can also be used but be careful as this may overheat other components on the PCB!

The “SS” connection point isn’t required here so to save work it’s recommended to keep this point unsoldered. Excessive heat isn’t needed so quickly glide your iron over the pin and to the connection point with just a bit of solder preloaded on to the tip of the iron in order to achieve a good connection.

Done? Good, you should have something that looks like the images above...

Now we can see where our programmer will be attaching, which means we’re at a really good point to test your PCB board and ensure it will accept your code. We will test by using Visual Studio Code and example code from the AmbaSat-1 GitHub repository.

The Ambasat-1 Motherboard has an LED fitted to the board to help show things are working as they should, but it’s not going to light up and flash on its own is it?

So, let’s make sure you have a nice cuppa tea to hand and move to the next step!

Remember that source code ZIP file you downloaded from GitHub? Well, let’s unzip the file to a folder on your computer. We suggest something simple like: C:/ambasat

Now it’s time to build our “digital workspace”. This step will help test your AmbaSat-1 board and chosen sensor. Let’s start with the LED code as this will give us a good indication that everything is working fine and also a good first look at using the example code. Make sure you have internet connection for this step.

In Visual Studio Code, click on file and find the option “Open Workspace...” Then find your AmbaSat folder where you have unzipped your code. Look for the “AmbaSat-LED” example file that’s should be located at: AmbaSat-1>Release>Source>Examples

Once open in Visual Studios Code, any library files which are needed by the project will be automatically downloaded. This may take a short while before building or editing can be dabbled with. Once loaded it’s time to build the LED program.

To build, click on the small tick on the bottom bar of your Visual Studios Code window, as indicated on the image with the big red pointer.

Building puts together the code into something usable by your AmbaSat-1. You will see the framework compiling when you do this, and if the build was successful you’ll be shown a green “Success” notification after the compiling is complete.

Now let’s get connected!

With the Programmer provided in your Kit, find and attach the wires to the programmer’s connection pins, they should slide on with minimum effort. You’ll notice each pin is labelled similarly to your PCB with markings for “DTR”, “RXD”, “TXD”, “VCC”, “CTS” & “GND” and these connect to the PCB pins as follows:

G - G

VCC - VIN

RXD - TX

TXD - RX

DTR - DTR

Again, keep in mind how sensitive your components are to static and electrical charge, stay grounded if and where possible while connecting the AmbaSat-1 PCB to the programmer. Once connected, plug the programmer into your computer’s USB port.

Now with your Built LED workspace, your programmer attached to your PCB and computer we need to copy the code across to the satellite. To copy across your build, click the small arrow located next to the build button on the bottom bar of your Visual Studio Code window.

Once copying is complete, you should see a line of text saying “SUCCESS” in the Visual Studio Code window. Now take a look at your satellite... See that flashy green LED thing? Well done!

This is a good test for our PCB as it shows us your AmbaSat-1 satellite is accepting programming and power is flowing through the circuitry correctly. This is also a good first exercise in seeing the cause and effect of simple code.

Now it’s time to get your chosen sensor mounted. There are a few different approaches to this stage but I will go through the best way I have found that works for a flush solder on the rear of your PCB. Why is this important? Your solarboard will later mount onto the rear of your PCB. Not only is the board delicate, we also need to reduce the risk of gaps between the two boards as this would allow the solarcells to flex and potentially break. There’s only so much room in the 3U Launch container and every millimetre counts. So, let’s be as neat, and tight, as we can.

In the spirit of every millimetre counts, check your AmbaSat-1 PCB and also the rear of your sensor board for any stickers that may stop your sensor sitting flush with the main PCB. This is where a scalpel or a sharp craft knife comes in handy. Remove any stickers to get mounting as tight as possible.

Once the stickers have been removed, use a square of double-sided tape (or light amount of appropriate adhesive... maybe not chewing gum) and roughly cover the rear of your sensor. Be sure to leave the connection pads clear! Stick your sensor squarely across the top right corner of your PCB so the last four connection points line up as perfectly as you can.

Now that you have your sensor in place, it’s time to solder it into position. In your kit’s bag of components you will find extra pins. (You could also use different materials such as resistor wire but the pins work just fine for this). With this method we will solder from the rear first as gravity will pull the solder down and through the connection point and we want a flush finish on the rear, not a conical point like you often see where solder is used. Take four pins, and a small amount of Blue Tack if you want to be Hi-Tech; I like to roll out a small Blue Tack sausage the same length as the sensor, take the Blue Tack and place it over the top of the sensor connection points.

Turn the board over so your satellite is facing downward. Lightly apply a small amount of pressure to the corner above your Hi-Tech sausage (caution: do not eat the sausage). With your four remaining pins, remove them from the plastic binding (or remove later with snips) and feed them into the first four holes from the left at the rear of you PCB passing through both the sensor and the PCB until you feel them connect with your Hi-Tech Sausage.

Once you’re happy that all pins are through, use some sharp snips or pliers to cut the pins as close to the board as possible to help form a flush finish once soldered. If any pins are still protruding through the rear, gently tap them deeper into the Hi-Tech Sausage until they sit flush or become slightly embedded.

Now that you have the pins cut down at the rear, it’s time to solder them in place. Using your soldering iron, heat the connection pads one at a time for a second or two before feeding in a small amount of solder. You’ll want to feed the solder on to the heated connection pad and into the hole, not feeding directly on to the iron. Less is more and we don’t need much solder in place. Keep in mind, more solder may trickle though once we solder the top side of the sensor board.

Once the desired amount of solder has been added, remove the solder wire and briefly hold the iron in place for a moment or two before gently brushing away from the connection point. This should leave you with a clean flush solder. Clean the tip with your sponge or head cleaner and move to the next connection point (this stops your iron from sticking). Repeat this for the next 3 connection points.

Check to make sure you haven’t applied too much solder, if the rear is looking a little bumpy, you may want to run over it with copper wick or use the spring-loaded sucker gizmo to clean up the area. Your solder should look nice, smooth and flush... no bumps or conical tips.

With all four connection points soldered at the rear it’s time to flip it over and remove your Hi-Tech sausage. Having a conical finish to your soldering top side of your sensor isn’t an issue like it is with the rear, so just roughly cut down your pins at this side and solder in a similar fashion. Heat the pad and pin for a couple of seconds, feed in the solder, keep the iron in place for a second or two longer than the solder wire and gently lift upwards to have a conical finish. Repeat this of the four relevant connections and view images above to see how the Sprite should be coming along.

Once soldered in to position, check the rear of your PCB, you may find your flush solder has now bulged slightly... If so, while holding your PCB upside down, run your iron over the solder a moment to allow the solder to run flush again.

Similar to the LED test earlier, we’ll now go over a quick way of testing your sensor. The sensor you have chosen will have a Visual Studio ‘workspace’ amongst the source code files we downloaded earlier. Open Visual Studio Code Go to file- Open workspace; find the workspace relevant to your chosen sensor located under "Examples" in your "Ambasat" folder.

Once loaded, in the same way as you did earlier, hit the build button (little tick on the bottom bar). Once the build is complete, you’ll get a chunky green “SUCCESS”.

When ready, connect your satellite to your programmer, and then the programmer to your computer. Make sure wires are connected in the correct sequence and remember to be wary of static, keep yourself grounded wherever possible.

Copy this build across to your satellite by clicking the small arrow near the build button. Don’t worry if this stops the LED from flashing, there’s only limited memory available after all.

Once copied across we will take a look at our terminal window. This will give us a direct look at the data your sensor is picking up.

The terminal can be accessed by the plug shaped Icon on the bottom bar of Visual Studio Code and will display the data that will be fed to the AmbaSat Dashboard once we link your device in the next step. As you can see, sensor 03 is giving us the rundown of the current conditions in the AmbaSat office, this shows it works

So, we have a working satellite board, a functioning sensor mounted... But what good is that if we can only read data while it’s plugged in? This is where TTN and LoRaWAN comes into play!

What is LoRaWAN?

LoRaWAN stands for Long Range, Wide Area, Network; it uses sub-gigahertz radio frequencies which have a proven functional distance of 700km+ (line of sight) so more than enough for our target of 310km in Low Earth Orbit. Luckily, with the AmbaSat-1 kit, you have a LoRaWAN transceiver pre-soldered to your PCB!

So ok, we know how our little Sprite Satellites are going to be talking to us, but how are we going to listen? This is where the non-profit organisation TTN (The Things Network) comes into play.

What is TTN? Well in their own words:

"The Things Network is about enabling low power Devices to use long range Gateways to connect to an open-source, decentralized Network to exchange data with Applications."

They do this brilliantly with the aid of people who freely install gateways worldwide to aid in their own or other’s tinkering. Currently there are over 16,600 gateways worldwide and growing day by day.

Check them out with the link below.

https://www.thethingsnetwork.org

So how do we make use of this technology? Back at AmbaSat HQ, we pre-register your device on TTN and provide you with three important parameters through your AmbaSat dashboard account (you should receive log in details via email shortly after shipping). So, what information do we need to access and where do we find it? You will need:

NWKSKEY - Network Session Key

APPSKEY - LoRaWAN AppSKey, the application session key

DEVADDR - LoRaWAN end-device address

To find these, log in to the AmbaSat Dashboard (you'll have been provided with your log in details shortly after your kit has been dispatched) and select the link to settings. These will now need entering into your code so that your AmbaSat-1 is correctly identified and knows who gets the data it is reading.

With your satellite connected via your programmer, close your terminal and open a new Visual Studio Code window. In this new window, open the “AmbaSat-TTN ‘workspace’” found in your AmbaSat folder, then open the “main.h” file; which should be found around here: Release>Source>Examples>AmbaSat-TTN>src. Once the main.h file is open in the work space you’ll see a new screen here in this borderline “Matrix”-style file, you will get a rundown of what your code does and how everything works. Congratulations, it’s now time to get creative, modify and edit code and get your satellite to do its thing.

Make sure you have your Network Session Key, App Session key and Device address to hand for this next step (or temporarily copy and paste them into the file so you don’t have to keep switching windows).

Scroll down in your Visual Studio Code window until you see lines of text similar to the image above, this is where you’ll input your unique keys and device address.

With your keys and address to hand, replace the values with your own
two digits at a time, ahead of each “0x”.

For example, if you Network session key was:

5A E0 69 0C 7E E4 F4 A9 73 88 E2 1C A7 5B FDB1

You would change these underlined values in this line:

{0xE8,0x48,0x7D,0xF9,0xCD,0xF6,0x17,0x2A,0x3C,0x31,0x8F,0x26,0x61,0x77,0x9D,0xEF};

To match the values of your unique Network session key like so:

{0x5A,0xE0,0x69,0x0C,0x7E,0xE4,0x4F,0xA9,0x73,0x88,0xE2,0x1C,0xA7,0x5B,0xFD,0xB1};

Double check your values are correct, maybe triple check if you’re anything like me. Once you are sure you have your values input correctly, hit the build button to compile your code... All good? You should see another “SUCCESS” at the bottom of your window. Now with your code compiled, hit the arrow button on the bottom bar of the window to throw it across to your satellite. “SUCCESS”? Well done.

You can now safely disconnect your programmer from the computer.

Finally, connect your battery pack to the satellite (Red to VIN and Black to GND) and log in to your AmbaSat Dashboard account to see your data being received to your own personal ground station!

Congratulations and well done! You have just taken the first steps of an exciting journey into Low Earth Orbit and beyond.