back to article Raspberry Pi sizes up HAT+ spec for future hardware add-ons

The Raspberry Pi project has released the first revision to its Hardware Attached on Top (HAT) spec, along with an update to the RPi 5's PCIE handling tools. Revealed in a Friday post penned by chief operating officer and hardware lead James Adams, the HAT+ spec [PDF] has four main changes: HAT+ boards must be electrically …

  1. Jusme


    I see where they're going with this, but I hope they don't lose sight of the biggest USP of the Pi - the ability to tinker with hardware via GPIO on a cheap (throw-away) module. PCIe is hardly a hobbyist accessible interface, and by the time you've added M2 SSDs etc. and made this a (pretty decent, if still minimal) ARM PC, you're not going to want to be poking wires into it.

    I'm sure they've run the numbers and know that a lego-kit PC is probably going to sell better than a souped-up microcontroller, but learning about the nuts and volts is something we seem to be losing out on these days </grumpy old man>

    1. Graham Dawson Silver badge

      Re: Interesting...

      GPIO is still there. The PCIe connect is the small white ribbon connector at the back of the board, next to the logo.

    2. elsergiovolador Silver badge

      Re: Interesting...

      PCIe is hardly a hobbyist accessible interface

      Why not? You can hook up an FPGA to PCIe, get your PCB manufactured in China for peanuts and Bob's your uncle.

      It's not the 80s.

      1. Flocke Kroes Silver badge

        Re: Interesting...

        It is not a standard PCIe socket. Attaching an FPGA will not be straight forward - until a Pi to standard PCIe socket turns up. (Probably at about the same time as a Pi 5 if you order today.)

        1. elsergiovolador Silver badge

          Re: Interesting...

          It's probably a 30 minute jobbie in KiCad to create a custom footprint for the connector, if someone already has not created one.

          Plenty of tutorials on YouTube how to do it or how to hook up an FPGA to PCIe.

          To be fair, everything is not straightforward like even attaching a LED to GPIO and make it blink, in the beginning.

          Not saying that you should get your grandma to come up with HW inferencing running on FPGA to accelerate generation of crotchet patterns.

    3. John Robson Silver badge

      Re: Interesting...

      I think there are at least three markets here.

      - The embedded industrial market, which pays for alot of the development.

      - The educational/prototyping "poke bits of wire into a GPIO array (which often leads to the other two).

      - The functional product, which may have "bits of wire" trailing out, but also wants a stable storage mechanism.

      It's also common for devices to go from market 2 - 3, and the ability to chuck on a hat for an SSD rather than relying on an SD card.

  2. sanmigueelbeer

    That's a big HAT+ to fill.

    (Exit is that-a-way, right? I'll see myself out, TYVM.)

    1. Lon24

      So big I'm trying to work out where the fan goes.

    2. Jamie Jones Silver badge


      I'm only here for the hat puns, I con'fez.

      1. JT_3K

        Stop, I can't beret any more.

  3. Dwarf

    Local storage

    I'd love to see a Pi come with the M2 socket on the bottom of the board, that way, no need for a Hat, cable to connect it, connectors both sides to plug the cable into and all the expansion pins and footprint for a HAT remain free. Surely this must be cheaper and more useful than this approach ?

    It would be even nicer if the SD cards went away and a SATA port existed. The biggest problem I've found with Pi based projects is that the SD cards destroy themselves over a couple of years and you have to rebuild them from scratch again or implement off-host backups / regular imaging of the SD cards to fall back to when they start to fail. This is based on using well known branded cards and a reasonable number of Pi's doing useful things in a variety of places.

    I've had similar experiences with tiny form factor USB storage, which is effectively the same thing, just in a different shape package.

    1. Leigh Brown

      Re: Local storage

      Pimoroni are going to offer something that pretty much gives you that...

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