Task: Build an A8PicoCart for Booting Software on an Atari 8-Bit Computer from a Raspberry Pi Pico Clone
Needed: A8PicoCart circuit board, Raspberry Pi Pico Clone, 3D-printed case, soldering iron
Time: 30-60 minutes
Disclosure: Note that as an eBay Partner Network Affiliate, I may earn from qualifying purchases.
Introduction
I have previously posted about the A8PicoCart that uses a Raspberry Pi Pico clone to manage and deliver cartridge ROMs (.ROM or .XEX) to the Atari for booting. These can be purchased assembled on eBay or Etsy for around $25 to $30. Alternatively, you can build your own for around $5 or $6. I recently purchased all the parts and assembled 10. Here are the instructions.
Instructions
Before starting assembly, I recommend first reading the Github page for the A8PicoCart project. I also recommend watching this YouTube video on how to assemble one.
The first thing you need are the pieces (total cost below at less than $5 per unit). Alternatively, you can pay $10 to $15 for a kit from eBay.
- I ordered 10 circuit boards from PCBWay using a shared project that already has everything you need loaded including the Gerber files found in the Github and the settings. Simply add it to your cart and then wait for them to review the order and approve it. You can then choose shipping. The 10 boards were $10. With tax and international shipping using DHL it came out to $27 or $2.70 per board.
- Next you need the Raspberry Pi clone. The cloned version comes from China and is different than a standard Pi Pico which won’t work. The good news is these clones are really cheap. I bought 10 Pico clones from AliExpress for $22 which included free shipping for orders over $10. So, these are just over $2 per unit. Note that these come with the pin headers that need to be soldered to the Pi clone and the circuit board.
- OPTIONAL: The instructions also call for a switch that freezes the Atari allowing the Reset switch to reboot the restart the A8PicoCart. This is supposed to save wear and tear on the power switch, but I find it really unnecessary. I ordered a set of 20 Uxcell switches of size 6x6x9mm from Amazon for $7.29 ($0.36 each) with free Prime shipping. Note the pins on these needed to be straightened to fit and were not long enough to poke through the circuit board. I was able to make them work. You might look for a better alternative.
- Finally, you need a 3D-printed cartridge case to complete the assembly along with two M3x15 screws to hold the two shell halves together. I was able to print this myself using my new Bambu P1S 3D printer with the STL print files included on the Github. This design uses about 28 grams of filament according to my slice software. At about $15 per 1000 grams of filament this is a cost of just under $0.50 per cartridge. If you don’t have a printer, you can order the case(s) from a 3D-printing service by providing the STL files or even add it to your PCBWay circuit board order if you use them (yes, they print).
Assembly is quite easy just requiring some soldering. Simply insert the long side of the pins (yellow above) into the backside of the circuit board (front / up is labeled). Then insert the Pico clone into the short pins with the USB connector toward the cartridge contacts as indicated by the arrow on the circuit board (see below). Hold the board steady with some clips or blue tack and solder the short pins to the Pico clone and the long pins to the front of the circuit board. Then solder the switch to the board with the switch itself on the front. Finally, assemble the completed circuit board with Pico clone in the cartridge shell and fasten with two M3x15 screws. My screw kit did not have this size, so I used M3x12 with were just long enough to securely hold the case together.
The final step is to load the firmware. I connected my cartridges to my PC with a USB-C cable and loaded the a8_pico_cart.uf2 file from the Github into the Raspberry Pi Pico clone folder. The firmware automatically loaded and then the Pico clone was ready for some ROM files. Once the ROMs are loaded, they will show up in the menu for booting as shown above in the introduction.
Comments
It took me about 3-4 hours to assemble, test, and troubleshoot the 10 cartridges. Two did not work. I was able to fix one by reflowing some solder joints. The other I was not able to get working. I assume some part of the Pico was bad. I was happy to get 9/10 working given how cheap the parts are.
This is an easy build if you feel comfortable ordering parts from China and doing some soldering. The ability to build these for ~ $5 each in parts and sell them for $25 on eBay means there is a decent profit margin if you are looking to unload some.
I really love how easy this device is to use.
Next time I plan to alter the source files for 3D printing the cartridge case. I will probably remove the hole for the reset switch which I think is completely unnecessary. I will also remove the inset region for the name badge and create something that includes the name on the print, so a separate badge doesn’t need to be printed and then glued to the case.
I have these extras I assembled for sale on my Etsy shop for $30 each.
