Actually, it’s 20 pictures that tell the story without me jabbering on about it too much and confusing the hell outta you; a/k/a “Not complicating the un-complicated.”
Before you move on, bookmark this site: https://core-electronics.com.au/tutorials/raspberry-pi/raspberry-pi-generations.html#Anatomy I find this site to be a great source of info regarding Pi’s.
NOTE: This is a build tutorial for the basic Pi-Zero Simplex mmdvm HotSpot. There are many other build-types/variants that will not be covered here. If you’d like to do a build using a duplex board in the Pi-Zero form factor, check out Lonestar mmdvm’s at: https://www.store.n5boc.com/product-page/mmdvm-duplex Of course, you will need to use a different case solution.
So, here’s all the parts. The middle left is the Pi-zero computer itself. The top left is the MMDVM “Hat” which is the radio portion that sits on top of the Pi-Zero (Ya see the little antenna stub-out that the antenna screws on to?) The info screen is integrated into the hat (That black glass square).
At the bottom left and right…that is what makes up the case…think of it as the “computer case.”
Oh yeah, “MMDVM” is an acronym for “Multi-Mode Digital Voice Modem”.
A closer look at the MMDVM “Hat.” When you buy the MMDVM Hat, it comes with the little black antenna as part of the purchase.
This is a shot of the underside of the MMDVM “Hat.” Those two black “blocks” are how the Hat connects to the Pi-Zero board.
This is a close-up shot of the Pi-Zero; a little dark because I’m a crappy phone photographer – sorry. That “silver square” on the left end…that’s where the Micro SD card is inserted which holds the Pi-Star Operating System that runs the show…
A side shot of the Pi-Zero so you can better see the GPIO pins that the Hat slides down onto… “GPIO” stands for “General Purpose Input/Output. Think of it as a wall receptacle in your home that you plug your Hoover vacuum into. The Pi-zero plugs into the Hat. The hat is the receptacle and the Pi-Zero has the prongs. You get what I mean…
The bottom portion of the case. We’re gonna mount the Pi-Zero onto this with the two short screws…
A better side view of the case bottom and the 4 threaded mounts.
Next, we set the Pi-Zero onto the case bottom and insert the 2 short screws in at either end of the GPIO pins.
Next, we set the MMDVM Hat onto the Pi-Zero, carefully lining the “plugs” up with the GPIO pins and gently pushing it down onto the Pi-Zero until it “bottoms out.” Easy-Peasey right?
The case will come with two of these pieces of Pex(?) tubing as well as four screws (two short screws and two long screws). They’re just spacers that support the MMDVM Hat on the opposite side from the GPIO.
Spacers and long screws installed…
Ahh, almost home free! We are now ready to install the case cover. Before you even start the build though; I recommend you play with the case. Take it apart and put it together a few times while it’s empty. Get yourself familiar with the process. The top of the case is pretty stiff so you may want to “spring” or stretch it open a little so when you do the final install you’re not fighting with it. You want to make sure you line it up correctly so as not to damage the antenna stub as you line it up and put it on…
Here it is half-way on. See those “slots”? There are tabs on the ends of the bottom portion of the case that fit into them as you slide it on. These hold the top of the case in place. You kind of have to “spring open” the top case as it slides down over the tabs. This is why I recommend playing with the empty case in preparation of putting it on at the end w/out damaging the internal components you just installed.
Ahh, groovy. The case top is on, you didn’t F-up the antenna stub putting it on. You’re golden… and feeling pretty damned good about yourself and as well you should…
At this point, you may screw the antenna on. If, at a later date you need to take the top portion of the case off; remember to remove the antenna first. Oh and, do you see the micro usb receptacle at the far right? That is where you’ll plug the power supply cord in. The other two receptacles (One Micro-HDMI and another Micro-usb) are not used as part of the HotSpot. NEVER plug the power supply into the middle micro-usb receptacle. That’s baaad Ju-Ju. Nothing good will come from it.
There it be…in all it’s glory. It’s almost like you’re some kind of electronics engineer…walking around your desk with your chest all puffed out shouting “That’s right, I built that bad boy!!” ;-p
The Micro-SD card. This is what holds the Operating System – “Pi-Star”. You will want a “U3” card that’s at least 16gb in size. While Pi-Star will run on an 8gb card, I recommend 16gb minimum to account for the space that software updates and the digital contact list will eat up that shows people’s call signs on the display etc. The bottom pic is of a 64gb card which is waaay bigger than you need but I picked them up because they were crazy cheap on amazon and they came with the SD adapter. Here’s a link: https://www.amazon.com/dp/B07ZD8JZZT?psc=1&ref=ppx_yo2_dt_b_product_details
We’ll go over installing the operating system onto the card & configuring it in another tutorial. For now let’s pretend we did.
The Micro SD card goes in this slot right here; copper contacts on the card facing down towards the board…
Here’s the card sticking half-way out. You’ll want to push it all the way in of course. When/if you need to remove it, steal your Wife’s tweezers out of the bathroom drawer. It makes it much easier to get it out instead of fat-fingering it. Remember to put the tweezer’s back so you’re not on her Sh!t list. You know how Wifey’s get when they can’t do their eyebrow pluckin’ because their tweezers have gone missing…
Plug the power supply in, flip the switch on the cord and Voila! You’re now the King of the Digital Airwaves!
Ahh yes, the pieces & parts list:
The case & MMDVM Hat combo: https://www.amazon.com/dp/B07Z8YP5VJ?psc=1&ref=ppx_yo2_dt_b_product_details
The Pi-Zero board: https://www.amazon.com/dp/B07W3GJTM1?psc=1&ref=ppx_yo2_dt_b_product_details
The 16gb Micro SD card if you already have an adapter: https://www.amazon.com/dp/B089DPCJS1?psc=1&ref=ppx_yo2_dt_b_product_details
Pi-Zero power supply: https://www.raspberrypi.org/products/raspberry-pi-universal-power-supply/ (You can get this on amazon as well. Raspberrypi.org recommends it be a 2.5amp PSU cord).
Hey, let’s face it. Not everyone wants to build their own. While it may have been fun to see how the sausage is made; building a Pi HotSpot may not be your thing.
In that case, I got ya covered: https://www.amazon.com/All-New-Hotspot-Assembled-Station-Raspberry/dp/B08JG9MG6Q/ref=sr_1_11?dchild=1&keywords=Pi-zero+MMDVM&qid=1618455762&sr=8-11
If you go with the pre-built option above, I’d recommend going with a power supply that is made by Cana or raspberrypi.org and trash the one that comes with the unit.
As mentioned earlier, this is just the build steps for the unit itself. Next time, we’ll go over the installation of Pi-Star on the MicroSD card and configuring it properly to talk to your radio and connect to the digital network.