I have a general question that’s been triggered by the specific experience of playing with the squishy Pi Pico keyboard (Pico RGB Keypad Base).
Pimoroni have helpfully broken out the Pico’s pins in rows parallel to the headers that accept the Pico itself, but my question is: how can I most neatly connect to these pins for a polished-looking project?
In this case specifically I have an I2C device (an Adafruit one with STEMMA QT / Qwiic connector) and a relay that needs to make use of ground, 3V and a GPIO pin. This can be achieved on a breadboard and only the Pico itself using standard male jumper leads but I wondered what the cleanest way to make use of these pins / all the pins would be for something clean and semi-permanent?
Some ideas I’ve had:
- Solder either a full or small partial row of male headers in place along the rows of PCB holes and use them as “plugs” for some female jumper leads heading off to the external modules,
- Somehow mount the entire squishy keyboard board onto some sort of larger assembly I put together?
- Attach wires directly to the broken out pin holes (no idea how, just wondering if there’s some clever little gadget that makes this a clean and reliable connection).
Like I say, kind of a general question of “how to neatly and reliably connect to pins that aren’t fitted with headers”, so any general tips are welcome, as are pointers toward useful types of connectors / clips / I don’t even know what.
One way to do it is solder a ribbon cable to those header solder pads.
Ribbon Cable - 10 wire (3ft) (pimoroni.com)
Ribbon Cable - 6 wire (15ft) (pimoroni.com)
Separate the wires at one end. Strip the ends and tin them with solder. Then push them up through the holes from underneath and solder in place. Using only the pads for the pins you need on the keypad circuit board.
The other end of the ribbon cable can then be soldered to a proto board etc.
I’ve found having these on hand comes in handy some times.
Breakout Garden to STEMMA QT / Qwiic Adapter (pimoroni.com)
And the cables.
JST-SH Cable (Qwiic / STEMMA QT / Qw/ST compatible) - JST-SH to JST-SH - 200mm (pimoroni.com)
You could just cut the connector off of one end and solder it to the keyboard header pads. Then plug the other end into the qwicc connector on the i2c device.
Ah yes I’ve found the breakout garden adapters really useful in conjunction with JST cables for tidying up prototypes too!
I think for this one I’m aiming for something less temporary / hacked-together-looking than a breadboard prototype but still ultimately reusable so I don’t want to solder wires directly to the board. It feels like soldering a pair of 20-pin male headers onto the board is the way to go probably.
These will work, once you trim the male pins.
Pico Stacking Header Pack (pimoroni.com)
@alphanumeric can I confirm what you mean please? Is the idea that I’d get a headerless Pico and add stacking headers to it such that it has male headers coming out of its back and female headers on its front? I’ve not seen stacking headers before so unsure how that’s meant to attach.
Ok, on the RGB Keypad there are those two rows of solder pads, one down each side of the Pico. They are each a single row of 20. As are those headers I linked too. I couldn’t find a non stacking version of them.
One option is to solder those headers to the keypad circuit board, then cut off the excess male pin lengths. Female side up would be the way I’d go. You can then plug in male jumper leads. It’s functional, might not be so good to look at with the jumpers plugged into them.
You could solder them to a Pico, and then plug that into the RGB keypad, but why bother? IMHO, it will look nicer the other way.
This, for me anyway, is one of the more frustrating parts of building something from bits and bytes. Making it functional and look good.
I have on occasion used these Perma Proto Boards. Quite often actually, with Pi’s and Pico’s.
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Used one of these on my last build.
Pico Proto PCB (pimoroni.com)
Guess what I built? - Discussion - Pimoroni Buccaneers