I started this design prior to going out of commission for various reasons (including a stay in hospital). I dug it out again the other day to see if my brain was up to working again (epilepsy leaves me a bit off, sometimes for weeks). Things seem to be ok, even if I'm still suffering from some of the physical problems!

So, Elemento.
The enclosure costs about £1.47 from AE. No screws, just clips together.
AE link
The PCB is my first serious attempt at a 4-layer board.
Designed to be easy to assemble for just about anyone who can solder.
Although there is SMD work there is nothing smaller than 1206. The bits you *will* break while practicing are the two LEDs. lol
Built in 4-port USB hub
Will accept either the Adafruit DVI breakout module for HDMI or a little board for VGA output.
Choice of 2 different full size SD card sockets or a micro SD card module (not SMD).
RTC with CR2032
40-pin Pico socket.

You need a short lead with a "mini" plug to fit your Pico and D+ / D- connecting to the hub. You simply unplug it for installing MMBasic then reconnect it.



Eight uncommitted GPIO pins on the front for the user.
PWM audio. Sorry, but there's not much space and I can't hear stereo anyway!

The clever bits are the changeable display module and the Pico. The 40-pin layout is completely standard so any pin-compatible device can be used. You will probably want to run the USB firmware though as otherwise your only access is the console. In theory it will accept anything from the original Pico to the Pimoroni Picp Plus 2 W and you can upgrade from one to the other. The VGA module is the same footprint as the Adafruit module. Both are intended to be screwed down onto M2.5 tapped spacers to reduce the strain on the connections. Note that you have to fit the display board *after* screwing the PCB down as there is no access to this screw after.

As usual with my designs, the components are generally cheap and cheerful. I'm just starting to check it over so comments welcome.

Nice. Like the case. Any way to squeeze in PSRAM? Even on the underside?

For that simply plug in the Pimoroni Plus 2 W. :)   Linky
It's not a cheap module (£16.80) but it includes 16MB flash, 8MB PSRAM and Qwiic. I think the PSRAM select is on GP47, where you would expect it for Pimoroni. It may be changeable, I'm not sure.

If you aren't bothered about wifi/bluetooth then they also do the pico-plus-2 for £12.90 in the same form factor. You may get the A2 stepping chip though.

I don't know of any other 40-pin module that includes PSRAM.

I'm guessing that the cases were intended for something like an active antenna. The outer finish is far nicer than I'd expect for something like a thermostat and the cable entry position is nicely rounded (I tried but I couldn't make use of it!).
.
Edited 2026-07-08 18:17 by Mixtel90

I checked the schematics and the Pimoroni modules have PSRAM_SEL hard wired to GP47.

Mick,

Maybe a stupid question, ... why not put the VGA down on the main board. For HDMI, simply do not populate the parts, and stick the adafruit board in.

I checked the housing, and you have to put the board in sideways (the cooling ribs are at the side). How can you put the board in when all holes for the USB/VGA/audio/reset switch stick out on both sides (front/back of the PCB, but sides of the gutter form top of the housing ?

Regards,

Volhout
Edited 2026-07-09 16:49 by Volhout

I did consider doing that with the VGA but there is a problem with the PCB fixing screw in that corner. There is no access to it so to get the display connector as tight into the corner as possible it has to plug in. So both the VGA and the Adafruit module are mounted connector-side down, on spacers.

Nothing along the front or the sides of the board projects through the front or sides of the case. Or at least it shouldn't. :) Reset buttons are supposed to be "down a hole and poke it with a stick" type. It should be easy enough to hook the rear components of the PCB into the case then hinge them together.

Right, I have a set of slightly modified prototype boards on order. That includes a veritable host (5 panels of 8 each) of the VGA adapter modules. :)

I don't know if anyone can use a module that allows a VGA monitor to be connected to the HSTX pins as laid out for the Adafruit DVI breakout. It could also be used a combined socket and resistor matrix to plug into a breadboard. No promises yet, but I'll see what they are like when they turn up. It's my first attempt at using JLCPCB's panelizing system with V cuts.

The main boards are, as I mentioned previously, my first serious attempt at working with 4 layers. It's passed my usual SL6 point-to point checks and the DRC so most of it might work. :)

The total cost of all the boards, including standard "el cheapo" shipping and taxes, was £18.95.

No gerbers yet. I'd rather like it to work first. :)  The circuit diagram is almost done and I'm fairly well on with the manual. Yes, I still do manuals. :)

Still need to get some more bits from AE - I'm running out.

  Mixtel90 said  

I don't know if anyone can use a module that allows a VGA monitor to be connected to the HSTX pins as laid out for the Adafruit DVI breakout

How about the HSTX pins as laid out for the DVI sock?



Might that be useful? (Not specifically for this project, of course.)

I had another thought earlier....


Ok, so the SD card on the display isn't used and there's no brightness control but the LCD display is fitting onto the same HSTX pins ising a simple adapter over shortish wires.  :)

Internally the SD card is on SPI2, but on different pins. Just redefine it for bitbang mode.

.
Edited 2026-07-13 02:41 by Mixtel90

  Mixtel90 said  

OPTION SYSTEM SPI GP14, GP15, GP12
OPTION LCDPANEL ILI9341, L, GP16, GP17, GP13
OPTION TOUCH GP18, GP19

Nice. But 3V3 is a flying wire (if a "sock" board or the Adafruit pinout is what you were thinking of).

~
Edited 2026-07-13 04:08 by lizby

That's fine. My board has a 5V header and the Adafruit board is fitted with a flying lead to plug into it. A LCD board could work in the same way. If you want 3V3 for the display then that could be fed from that, I suppose. I had to do it that way as the VGA connector would hit a 5V header aligned with the Adafruit.

Remember, the display boards are "upside down" so that they can be lifted high enough to miss the PCB fixing screw and still fit into the case. :)