Sixfab / Custom Raspberry Pi HAT & Hardware Development
Sixfab designs custom Raspberry Pi hardware: HATs and add-on boards for Raspberry Pi 4 and 5, carrier boards for Compute Module 4 and 5, and custom boards that consolidate a multi-HAT prototype into one production-ready PCB. Schematics, layout, DFM prototypes, validation and manufacturing come from one team, a Raspberry Pi Approved Design Partner. First prototype in 6 to 8 weeks, production around week 12. Need a complete edge AI computer rather than a board? See Custom Edge AI Computer Design.
It is a board-level hardware design service for products built on Raspberry Pi. You bring a working prototype, often a Raspberry Pi with two or three HATs and a breadboard, or an interface list. Sixfab designs the custom HAT, add-on board or Compute Module carrier board that replaces it, builds and validates assembled prototypes, and manufactures the board in its own ISO 9001 facility at whatever quantity you need. A standard Raspberry Pi stays at the centre of the product; the custom board carries the interfaces, power, connectivity and mechanics that make it yours.
It is the right service when the deliverable is a board. When the deliverable is a complete, certified computer with AI acceleration, an enclosure and a fleet behind it, that is our Custom Edge AI Computer Design service, and this page points you there.
Choosing a route
There are no hard entry requirements. A single custom HAT for a research rig is a valid program. What follows is guidance on when this service is the economical route, and the free feasibility review confirms it for your project before you commit to anything.
Volume, budget and purpose shape the recommendation. They never disqualify a project. We make sure you see the economics of each route first, including the one where a standard product already does the job.
Two services, one team
Both are run by the same engineers and both start with the same free feasibility review. The difference is what you receive at the end: a board, or a finished device.
| Custom Raspberry Pi HAT & hardware development this page | Custom Edge AI Computer Design | |
|---|---|---|
| What you receive | A production-ready board: custom HAT, add-on board or CM4/CM5 carrier board, with the design files | A complete, certified edge AI computer: carrier board, compute module, AI accelerator, enclosure, starter image |
| Starting point | A Raspberry Pi prototype, a HAT stack, or an interface list | Product requirements and a workload that has to run at the edge |
| Compute | Any current Raspberry Pi, including Compute Module 4 and 5 | Raspberry Pi Compute Module 5 with an AI accelerator chosen per workload |
| Enclosure | A standard enclosure from our partners, machined by CNC or laser for your connectors, when the program needs one | Mechanical, thermal and industrial design of the device |
| Compliance | Pre-compliance and radio pre-tests, plus the documentation your product certification needs | CE, FCC and IC campaigns for the finished product, run by Sixfab |
| Typical schedule | First prototype in 6 to 8 weeks, production around week 12 | 24 to 25 weeks to production release |
| Best for | A product that stays a Raspberry Pi plus your board | A product sold as a finished device, often with on-device AI and a fleet behind it |
| Start here | Free feasibility review → | Custom Edge AI Computer Design → |
Scroll the table sideways to see both services.
Capabilities
Four kinds of custom Raspberry Pi board, all designed, prototyped and manufactured in-house. Sixfab’s own product line is Raspberry Pi add-on hardware, so every program starts from proven power trees, antenna layouts and connector choices rather than a blank sheet.
Built to the HAT+ mechanical and electrical specification: 40-pin header, ID EEPROM, correct power behaviour, stackable when it should be. Sensors, isolated industrial I/O, RS-485 and CAN, power management, cellular, GNSS: whatever your product needs on one board.
When the product outgrows a Raspberry Pi 4 or 5, a carrier board built around CM4 or CM5 gives you your own connectors, your own form factor, and a compute module Raspberry Pi has committed to supply into the next decade.
Three HATs, a breakout board and a USB hub is a fine prototype and a poor product. We consolidate it into one custom Raspberry Pi board: fewer connectors, lower cost per unit, and a bill of materials you can source at volume.
Sixfab’s home ground. Pre-certified LTE and 5G modules, antenna selection, placement and matching, SIM and eSIM, GNSS, and the pre-compliance work that keeps a radio design out of trouble at certification.
Battery and solar power, charging and battery management, deep-sleep modes and safe shutdown, designed onto the board rather than bolted on beside it.
Display interfaces, touch and status indication integrated on the board, with the Raspberry Pi’s own display connector kept accessible where the product needs it.
A standard enclosure from our partners, adapted by CNC and laser for your connectors, antennas and displays, so the board ships as a unit you can mount. Tooled enclosures are a complete-device job.
How a program runs
This is the schedule we quote against for a typical custom HAT or carrier board: first assembled prototypes in your hands in 6 to 8 weeks, production release around week 12. Three go/no-go gates, and the first one costs nothing.
A technical compatibility screen, not a design exercise. We look at your prototype or interface list and answer the questions that decide the program: can this be one board, what do the Raspberry Pi’s power and I/O budgets allow, which interfaces conflict, what does the radio need, and which of our existing HATs already covers part of it.
You get: a written yes or no, a recommended board architecture, and the risks we found.
Interfaces, form factor, environmental targets, quantities and the milestone schedule are fixed in writing. Proposals go through leadership approval before they reach you, so what you receive is what we can commit to.
You get: a statement of work and a milestone-billed NRE schedule.
Block diagram, schematic capture, PCB layout, then the 2D and 3D check against your mechanics and the Raspberry Pi it mounts on. Each is a customer-approved milestone, and each approval releases the next NRE instalment. You are never more than one milestone away from being able to stop.
You get: block diagram → schematics → PCB layout → 2D/3D check, each for review and sign-off.
Fully assembled DFM prototypes on the same process the production units will use, with the starter image flashed and every interface brought up on our bench before they ship to you.
You get: assembled prototypes in your hands, typically in week 6 to 8.
We validate power, signal integrity, thermal behaviour and every interface, and run pre-compliance radio tests where there is a radio. Then you run the board against your own application and field conditions. Your acceptance is the manufacturing trigger; we do not build production units on our own opinion of the design.
You get: an internal validation report, pre-compliance results, and the deciding vote.
Design freeze, a frozen bill of materials, and the first production build in our own ISO 9001 facility at whatever quantity you need, with fulfilment from the EU and the USA. Changes after freeze go through formal, priced change orders.
You get: tested, serialised boards delivered against your order or rolling forecast.
Durations are typical for a HAT or carrier board of moderate complexity. A radio, an unusual connector set or enclosure adaptation moves the schedule. Your quoted schedule is fixed at Gate 2.
Design notes
Six things that decide whether a custom HAT behaves like a product or like a prototype. You do not need to solve them to start; they are what the design review resolves. They are listed so you can check any vendor’s answer, including ours.
Numbers match the list. The dashed square is the Raspberry Pi’s processor under the board; the inset shows a stacked HAT on an extended header.
The HAT+ outline, mounting holes and header position are fixed by the specification. Get them right and the board fits every Raspberry Pi 4 and 5, every case designed for a HAT, and every stacking header.
A small EEPROM on the reserved I2C pins lets the Raspberry Pi identify the board and configure its GPIO at boot. It is what separates a HAT from a board that happens to plug in.
The Raspberry Pi’s 5 V and 3.3 V rails have limits, and a HAT that powers the Pi has its own rules. Radios, motors and displays usually need their own regulation on the HAT.
Every pin does one job. Conflicts with the camera, the display, PCIe on Raspberry Pi 5 or a second HAT are found on paper, not on the bench.
If the HAT must stack, connector heights and keep-out zones are designed in from the first layout, along with access to the camera and display connectors.
The HAT sits above the processor. Airflow, hot components and the enclosure are considered together, so the Raspberry Pi does not throttle under your workload.
Scope
The most expensive misunderstanding in a hardware program is a responsibility nobody thought was theirs. Here is the split, in plain language, before you sign anything.
Included in the program
Outside this service
You own the foreground IP of a paid design: schematics, layout, bill of materials and manufacturing files are deliverables. Sixfab keeps its background IP, the reference blocks we reuse across programs. On the productisation route, where NRE is waived against a production commitment, Sixfab retains the design and you get a lower entry cost. Which route applies is decided at Gate 2.
Once the design is frozen for pre-production, every change runs through a formal engineering change order with its own quote and schedule impact. It is what keeps a frozen design frozen and a validated board validated.
Raspberry Pi 4, Raspberry Pi 5, Zero 2 W, Compute Module 4 and Compute Module 5. If your prototype runs on it, we design around it. If a Compute Module is the better long-term host, the feasibility review says so, and why.
Proof
The quickest way to judge a HAT design service is to look at the HATs it sells. Sixfab’s own product line is Raspberry Pi add-on hardware, sold worldwide through our store and distributors. Every custom program starts from that catalogue: proven power trees, antenna layouts, connector choices and manufacturing test fixtures.
4G/LTE and 5G HATs built on pre-certified modules, with SIM and eSIM: the reference design behind every custom board we build with a radio.
An NPU on a HAT+ form factor, launched in June 2026: the reference when a custom board needs on-device inference, and the point where a board program can grow into a complete edge AI computer.
A complete Raspberry Pi Compute Module 5 edge computer, designed and built in-house: what a board-level program looks like when it becomes a finished device with certification, an enclosure and a fleet behind it.
Questions
Scope, cost, timelines and ownership. If your question is not here, ask us directly.
Yes. Custom HATs and add-on boards for Raspberry Pi 4 and 5 follow the HAT+ specification, including the ID EEPROM and the power rules, so the board behaves like a product rather than a prototype. Carrier boards for Compute Module 4 and 5 are designed around your product's connectors, form factor and mounting. The free feasibility review confirms which Raspberry Pi is the right host for the life of the product.
That is the most common program we run. Bring the stack, the breakout boards and the wiring; we consolidate them into one custom HAT or carrier board, remove the connectors and cables that fail in the field, and give you a bill of materials you can source at volume. The prototype itself is the best specification you can bring to the first call.
Yes. A carrier board is the right move when a product needs its own connectors, form factor or mounting, or a supply commitment beyond a consumer board: Raspberry Pi has committed Compute Module 5 to production until at least January 2036. Carrier design covers power, PCIe, camera and display, USB, Ethernet, and any cellular or industrial interface your product needs.
We do not modify Raspberry Pi boards themselves. We design the custom hardware around them: a HAT, add-on board or carrier board that gives a standard Raspberry Pi or Compute Module the interfaces, power and connectivity your product needs, and we manufacture that board for you. The result is a customized Raspberry Pi product under your name, built on a compute platform with a long supply commitment.
A custom HAT or carrier board is a board: you receive the hardware and the design files and integrate it into your own product. A custom edge AI computer is a finished device: carrier board, Compute Module 5, an AI accelerator chosen for your workload, enclosure, certification and a starter image, manufactured under one contract.
If you need the device, start on the Custom Edge AI Computer Design page. The same engineers run both services and both begin with the same free feasibility review.
No hard minimum. Prototype runs of a handful of boards and production runs in the thousands are both normal, and a single custom HAT for a research rig is a valid program. Quantity changes the economics of the route we recommend, never whether we take the project.
You own the foreground IP of a paid design, and schematics, layout, bill of materials and manufacturing files are delivered to you. Sixfab retains its background IP: the reference circuits and layouts we bring to every program. On the productisation route, where NRE is waived against a production commitment, Sixfab retains the design; the contract states which route applies before any engineering starts.
Pre-compliance testing and radio pre-tests are part of the program, together with the test reports and documentation your product's certification needs. Full CE, FCC and IC certification applies to the finished product placed on the market: when Sixfab builds the complete device, that runs under the Custom Edge AI Computer Design service; when you integrate the board into your own product, we support your campaign with documentation and, where useful, design changes.
For a HAT or carrier board of moderate complexity: first assembled prototypes in 6 to 8 weeks from contract, production release around week 12. A radio, an unusual connector set or enclosure adaptation extends it. The schedule is fixed in writing at contract, and the first gate, the feasibility review, costs nothing.
Yes. Cellular is where Sixfab started. We design in pre-certified LTE and 5G modules, handle antenna selection, placement and matching, SIM and eSIM, and run radio pre-tests so the design does not surprise you at certification. Sixfab's own IoT SIM and connectivity plans are available separately if you want one supplier for the radio and the data.
Next step
Tell us what the board has to do, what it plugs into, and, if you know it, your expected quantities. We come back with a written yes or no, a recommended board architecture, and the risks we can already see. No hardware design work, no cost, no obligation.
Your prototype or interface list, the Raspberry Pi it runs on today, environmental targets and expected quantities; one-off builds welcome. Photos of the HAT stack are enough to start. Mutual NDA on request.
A go/no-go on technical feasibility, a recommended board architecture (HAT, add-on board or carrier), a schedule shape, and the economics of each route at your quantities.
First response within 24 hours. Feasibility findings within one week of the technical call, in writing.
