Teensy® 3.2 or Pico Assembly
Header pins and sockets, and cutting the VIN-VUSB trace.
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Header pins and sockets, and cutting the VIN-VUSB trace.
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Teensy 3.2 only applies to Core64. It does not apply to Core64c which uses a Raspberry Pi Pico. For the Core64c with Pico, simply align the Pico on the Logic Board with the USB connector at the top edge. Solder the castelated notches on the edge of the Pico to the Logic Board. That's it!
The Pico does not have firmware pre-installed. Go to https://github.com/ageppert/Core64/releases/
This part of the process is made up of cutting headers to length, filing or sanding the ends square, and a bunch of soldering. When you are done, you will have a few pins and sockets left over to use for other optional features.
Read through this whole section to see where you are headed, which is illustrated in the last image. The lengths of the pin headers will be different initially, and will require some trimming. This will help assure the Teensy® 3.2 fits well.
You must CAREFULLY cut a trace on the back of the Teensy® board before assembly!
See Step 1.
There are several optional OLED screens you can choose to add to the Core64. They are listed in Appendix C: Graphic Display Options. Some of those can be installed in the middle area of the Logic Board.
One particular option is the 128x32 Blue OLED Teensy® View made by Sparkfun. If you choose that option, you will not want to install the Core64 headers around the perimeter of the Teensy®. Instead, you will want to purchase and install long pin female socket headers such as the Teensy® Header Kit. See the Appendix for more details.
You may have noticed a warning sticker, or two... Here's the spot marked by the red arrow shown with reference to the back of the Teensy® info card with the official explanation:
Be careful to cut only this trace, on this layer. Do not cut too deep or you could cut a trace below this one. If you do, there is a forum post at PJRC on how to overcome the cutting of the inner trace.
After you cut the trace, measure for continuity between the two adjacent pads. Please be sure you have cleanly seperated those two pads. You do not want battery pack voltage and your USB port 5V to mix. Cutting this trace ensures they do not mix.
If you bought a Beta Kit, this step is already done for you. And you've got an extra set of sockets for whatever you'd like to use them in. You're welcome!
Otherwise, cut, trim, sand, file... and repeat until all of the Teensy® recepticle pins are filled like this:
The most important thing is to keep the sockets perpendicular to the board and each other so the stay in alignment. This will make it much easier to install the Teensy®. It also provides an alignment fixture for soldering the headers to the perimeter of the Teensy®. You can export an STL file of this jig I designed in OnShape to use to ensure the sockets all fit together smoothly, and have 90° alignments. (Print with the version number face down.) If you use the fixture, make sure the headers fit smoothly into the fixture without any friction. If you have to force them in, and you try to pull the header out by the pins, you'll end up pulling the pin out of the header socket and probably ruin it.
I strongly recommend trimming all of the leads on the backside for these socket headers, and making smooth solder joints so the Logic Board does not sratch or snag anything it is placed on or against (like your shirt).
Did you cut the VIN-VUSB trace on the bottom of the Teensy® yet? If not, go back to Step 1 please!
Before we proceed, here is a preview of how all of the headers are going to stack up for the Teensy®. Note how the center SMD header is offset downware because it is SMD. But make sure you install the outer thru-hole headers flush with the bottom of the Teensy. The helps ensure a solid right-angle connection to the PCB, and it provides a gap around the outside that you can use to seperate the assembly Teensy from the socket if needed later on.
Start with the innermost SMD 2x7 header. Alignment is critical, so take your time with this and get it right. Center it as carefully as you can in the pads, in both directions. Start by soldering just one pad, and tweak the position of the whole header ONLY when you have the solder pencil on that pad. If you try to rotate the header and the joint is solid, you will sheer the pad off the board.
Do not be tempted to insert the Teensy® into the female sockets until you have securely solder ALL 14 of the 2x7 SMD header pins to the Teensy®. There is a very high risk of tearing off the pads when you go to pull the Teensy® out. You can obtain a replacement Teensy® 3.2 from Digi-Key or another distributor.
Once you are satisfied with the alignment, proceed to solder the opposite corner solder pad.
If the alignment is still perfect, then proceed to solder the rest of the pads. If it's not perfect, reheat the first two joints and tweak it until it is. I'm not trying to be overbearing about this alignment. I know you can get it right and it really makes the rest of this go together easier if you focus on this step.
If you are not already in the habit of using flux when soldering, you are missing one of the best tricks of the trade! Not just flux core solder, but a flux pen or flux paste. It's the secret to shiny solder joints that "just flow." But don't breath it. Get a fume extractor and solder in a well ventilated area.
Now cut down the center 2x7 pins so they will be the same length as the perimeter headers when they are installed. All the pins will end up having the same length when resting on the tips after they are all soldered in:
Clean the flux from the 2x7 header solder pads now because it will be hard to access after the next step.
The long strip of header pins needs to be cut into several shorter lengths to populate all of the headers around the perimeter of the Teensy® board. When you install the headers, make sure they are perpendicular to the board. A good way to do this is to insert the Teensy with the headers loosely installed into the female sockets of the Logic Board. The Logic Board can hold everything in alignment as you work your way around the perimeter of the Teensy®, soldering all of the headers.
There is one pin header position that needs to be skipped or clipped down because there is not a hole in the Teensy® board for it. It is shown with the red arrow:
When you install the not-yet-soldered Teensy®/Headers in the Logic Board, you will need to slide the perimeter headers up towards the board so they are not pushed all the way into the sockets.
Leaving a gap between the header and socket on the perimeter is important in order to make it easier to remove the Teensy® from the Logic Board. You will need to insert a flat blade screw drive and gently pry between the top of the socket and bottom of the header, working your way around the perimeter evenly, to extract the Teensy®. For the sake of this assembly step, you can just leave the Teensy® in after you solder it. There is no need to remove it.
The center SMD 2x7 header will cause the whole Teensy® board to sit up a little higher than it would with just the straight perimeter headers. Here it is installed:
Clean the flux from the header solder joints on the top of the Teensy®.
Later, if you decide you'd like a lower profile installation, and everything is confirmed working, you could remove the sockets and solder the Teensy® headers directly to the Logic Board. I don't recommend doing that because if you have to remove it to troubleshoot, or want to repurpose the Teensy® for something else, it's a bunch of extra work to desolder it. You also risk damaging the boards.
The Teensy® assembly process is complete.
