The PortaSpeccy

For more information, and the BOM, go here: https://codeberg.org/Jonn-reenthused/PortaSpeccy

Here's the launch stream: https://makertube.net/w/eCL4u6Q3y2QBMZAw7QNTTC

A portable Spectrum Next running on a Tang Nano 20k

In the long line of pointless open-source nonsense here's my answer to the rubbish portable speccy's that were announced without a keyboard. Now, I ended up going too far and used a full keyboard and 7" screen, so it's quite large - but I may make a 5" screen version.

This is based around NextNano on the Tang Nano 20k - but you can also just go for the straight Speccy that's available for the Tang Nano and it should work just as well, possibly better.

If you're using the POS keyboard then you can find the setup file in hardware/PortaSpeccy.dat

Checkout the BOM for all the parts, there will be a livestream VOD available, but here's some quick instructions:

Depending on the screen you've chosen, it'll either screw directly to the four posts on Screen-Face or you'll need to use one of the universal adaptors You'll need to get +5v and gnd for the sound booster, if you're using the recommended Elecom screen then you can use a 1.0 JST connector to take it from the touch interface Connect the sound board, connect the speakers to the sound board. The speaker will stick to either side of the screen, over the grills cut out for the purpose.

The bottom of the screen should be at the side of Screen-Face with the square cutout.

Attach an HDMI cable and USB-C to USB-A to the screen and lead them out of the square cutout. Put the Screen-Back in place and use four M3x8 screws

Take the Keyboard-Face of your choice and the keyboard of your choice. If it's the POS keyboard then you'll need to upload the PortaSpeccy.dat file to it to setup the keys and configuration.

You'll need to dismantle the keyboard, keep the screws handy because these will be used to attach them to the Keyboard-Face.

Get the rainbow button and place it in the square cutout. Now feed the button through the circular hole suspended above it, screw the nut in place to hold it in.

Now, the complicated part.

Get the Keyboard-Back, this is where the majority of the components will need to be placed. The USB-C power board will need to have several wires attached. I recommend using 2.0 JST connectors where possible. The rainbow button will need to be connected to the 5v out ground and the K throughhole. I attached a floating 2.0 two-pin male connector on here and a 2 pin female on the button wires.

You need to connect the Tang Nano to the 5v out (it's on the side of the USB-C board) and the battery to the batter out which is at the opposite end to the USB-C port. I used a 2.0 three pin male connector for the 5v out (removing the middle pin) and a 4 pin to the battery connector (removing the two middle pins). I then connected the 5v out to the Tang nano by adding a 2 pin 2.0 JST male connector to the Tang nano and made a wire that connected the two. I also took the opportunity to split the ground wire so it also connected to a switch for proper isolation.

Be very careful with polarity here.

Make sure you've setup the Tang Nano. I'd tell you to follow the instructions on the github, but they aren't great. follow them for the NextNano.fs, that's fine. But for the other two files you need to get Boufallo's FlashCube. Put the Nano in program mode by holding down the little button near the USB-C port whilst turning it on. In the FlashCube program you need to open up the ini file I've mentioned somewhere, probably on the BOM, make sure the files match the name and position mentioned on the UI and upload. If it's successful then great. If the keyboard doesn't work then it didn't succeed.

The USB-C board can be placed on the raised platform on the back of Keyboard-Back. You can then use the USB-POWER-BRACE and two M2 screws to hold it in place.

You can now thread the SD card extension through the slot on the Tang Nano holder, this then goes into the Tang Nano. The Tang Nano can then be placed in the holder by inserting the USB-C port in first and then resting it on the HDMI port. You can also attach the HDMI cable from the screen.

The other end of the SD extension can now be screw in place on the raised platform at the front using two M2 screws.

If you're using a USB extension then this can be screwed into the side.

Now, add a USB hub to the Tang nano USB-C port, connect the keyboard, screen power and USB extension.

At this point you can add the battery. And stick down anything that's floating around.

Now add on the Keyboard-Face, tidy up the cables as much as you can and screw everything in place using 4 M3 screws.

Now, place the Screen on the keybaord base with the screen facing down. Grab two screen brackets and push them into the square hole on the base and the round hole on the screen. You can now use two M3 screws to hold them in from the back.

And that's it, if everything has gone right then it should now work.