A8PicoCart - UnoCart on a Raspberry Pi Pico

[TheSPY]

I finally finished building mine, was a fun little project and I learnt a lot.  As I didn't want the 3D printed logo insert or the button on the front, so modified the case to be smooth on the front.  I also wanted to have access to the "Firmware updates" without taking the cart apart so added extra hole on the back for button on the Pico.   I realised after I had assembled everything that the little button "backwards" on the main board wasn't long enough to stick out the case. So I also had to design a "button" extension. So I then went and made my own custom labels to suit..  I have attached all the relevant files if someone else wants to use them.  

A8PicoCart Label.pdf A8PicoCart blank front.stl A8PicoCart holes in back.stl A8PicoCart button.stl

[_The Doctor__]

On 5/23/2023 at 1:47 PM, electrotrains said:

Hi All,

 

I got a Raspberry pi pico a few weeks ago to have a play with and forgot about it. Then, after noticing a post here, I realised I couldn't resist having a go at using it to make a multicart for the Atari 8-bit. A couple of PCB revisions later, I'm pretty much done, and proud to announce the A8PicoCart!

 

Unfortunately the official Pico board hasn't got quite enough pins to make a proper multicart - you can emulate 8k and 16k carts, but that's about it. However I discovered that you can buy £3 purple Pico clones from China with 16Megs of flash, USB C and, more importantly, all the GPIO pins broken out, which is just enough to hook up the whole cartridge port.

 

So I've made an Atari 2600 multicart with the official Pico, and an A8 multicart with the purple Pico clone 🙂

(If you are interested in the 2600 version - I posted earlier today about it here).

 

Neither cart has any other components other than a Pico board and the PCB - so this will be a very easy DIY build.

 

Although the RP2040 used in the Pico is not formally 5V tolerant, it is rumoured that the non-ADC pins are, so I've used these, and hoped for the best. No problems so far after many hours of testing firmware versions! I wanted to go for an easy build, so wanted to avoid extra components.

 

The firmware is a purple themed tweaked version of the original UnoCart firmware, though I've added the 4 extra cartridge types recently added to the Ultimate Cart firmware. As there is no SD card, I've also written support to make the cartridge a USB mass storage device, so you can simply plug the cartridge into a PC with a USB cable and copy files over. This provides 15Megs of flash storage onboard for ROMs and ATRs.

 

Oh, and its also very easy to update the firmware on a Pico - just plug into USB with the BOOTSEL button pressed and drag a file onto the device.

 

There are 2 versions of the PCB at present - one with the Pico facing forwards so the status LED can be seen, intended for uncased use on an XE. The other has the Pico facing away so it will fit in a case and there are mounting holes to assist. At some point I will design a 3D printed case for it.

 

As usual I've got a load of spare PCBs, so if anybody wants an assembled board to help me test, get in touch?

 

Robin

 

Pico and even cheaper purple clone

PCBs

New Firmware

USB Mass storage mode

 

With its 2600 brother

wonder if this could be a double ender, 8 bit one end, 2600 the other, signal from power or other pin to determine which menu and serving method to run?