Raspberry Pi HAT Design Overview

lukat

lukat

Project Goal: Design a Raspberry Pi 5 HAT (Shield) featuring an onboard Arduino Nano, dual stepper drivers, and isolated logic.
  1. Mechanical & Stack-Up Requirements:
Form Factor: Standard Raspberry Pi HAT.
Height Clearance: Use a 13.5mm extra-tall 2x20 female header (stacking style) on the bottom of the PCB to ensure airflow for the Raspberry Pi 5 Active Cooler.
Socketing: Place two parallel 1x15 female headers on the top of the board to socket a removable Arduino Nano. Place two 2x8 female headers to socket removable A4988/DRV8825 stepper drivers.
  1. Power & Regulation:
Input: 2nd Screw Terminal for 24V DC.
Regulator: Implement a fixed LM2596S-5.0 buck converter circuit.
Layout: Place a SS34 Schottky Diode and 33uH Power Inductor in a tight loop with the LM2596. Connect the Tab (Pin 6) to a large copper ground pour for heat dissipation.
Filtering: 100uF/50V Capacitor at 24V Input; 1000uF/16V Capacitor at 5V Output.
  1. Opto-Isolation Barrier:
Isolation: Use a PC817-4 quad-channel optocoupler to isolate RPi GPIOs (17, 27, 22, 23) from Arduino pins (D2, D3, D4, D5).
PCB Layout: Create a physical isolation gap in the ground plane underneath the PC817-4. Do not bridge the Pi_GND and Power_GND planes.
Components: 220-ohm series resistors on the Pi side; 10k-ohm pull-down resistors on the Arduino side.
  1. IO & Peripheral Headers:
Servos: Two 3-pin male headers (GND, 5V, Signal). Connect signals to Arduino D12 and D13.
End Switches: Two 2-pin headers for homing switches (GND and Signal). Connect to Arduino D6 and D7.
Stepper Pins: Route Arduino D8/D9 to Driver 1 (Step/Dir) and D10/D11 to Driver 2 (Step/Dir).
  1. Routing Constraints:
Power traces (24V and 5V) must be at least 30 mil width.
Signal traces should be 10 mil.
Keep the switching regulator section far away from the Raspberry Pi GPIO header to minimize noise.
Pro-Tips for when the Design Loads: The "Airflow Gap": Once Flux generates the 3D view, check the space between the bottom of your PCB and the top of the Pi. The 13.5mm header is the key; if it looks too tight for the fan, you can even go up to a 20mm header.
Arduino Orientation: Check that the Mini/Micro USB port of the Arduino Nano is pointing toward the edge of the board. If it points inward, you won't be able to plug it in to program it once the shield is assembled.
The "Keepout" Zone: Make sure Flux hasn't automatically filled the area under the optocoupler with copper. You want a "no-man's land" of fiberglass there to ensure the High Voltage (24V) side can never spark over to the Pi (3.3V) side.
Pin 6 of the LM2596: In Flux, ensure Pin 6 (the large back tab) is connected to a Copper Pour or Vias that go to the other side of the board. This is your heatsink. If it's just a floating pad, the chip will overheat and shut down your 5V rail.
14h

flux

1:09

Thinking deeply about your request.

Creating an execution plan.

Drafting the execution plan.

Working on your request.

Creating high-level execution plan.

Considering file usage.

You want a new HAT-style control board with socketed controller and motor-driver modules, isolated logic, and onboard 24 V to 5 V power conversion.
  • I’ve created a ready-to-execute plan covering mechanics, power, isolation, routing, and validation.
  • Because this is a new design and you can’t edit the current project, start here: Create new project
  • Then click Start on the plan bar.
Set board constraints
Place isolated sections
Pick socket parts
14h
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@copilot how do I use Flux?
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copilot

To get started with Flux, you can follow these general steps:
  1. Create a Flux Account: Sign up for an account on Flux.ai.
  2. Migrate Projects: If you have existing projects in tools like EasyEDA or KiCad, you can follow the migration tutorials to bring them into Flux. Here are links to the tutorials for
    [1] and
    [2].
  3. Learn the Features: To get a comprehensive look at Flux’s features and how to integrate them into your workflow, check out the full documentation[3].
  4. Using the Simulator: To learn how to use the simulator within Flux, you can refer to the available tutorials[4].
  5. Hands-On Practice: Start by creating a new project and experimenting with the schematic and PCB layout tools. Add components from the library, connect them, and simulate your designs.
  6. Community and Resources: Engage with community resources, participate in discussions, and stay updated with Flux's news and updates.
Is there a specific aspect of using Flux you want to dive deeper into? Let me know!
[1] https://www.flux.ai/p/blog/easyeda-vs-flux
[2] https://www.flux.ai/p/blog/flux-vs-kicad-5-key-differences
[3] https://www.flux.ai/p/blog/flux-for-librarians
[4] https://docs.flux.ai/reference/how-the-simulator-works
1y
4
L1
Inductance
33uH
VOUT
+5V
R2
Resistance
1kΩ
+5V
+5V
R1
Resistance
3.0kΩ
C3
Capacitance
470uF
C1
Capacitance
1.2nF
  • Ground
    Ground
    A common return path for electric current. Commonly known as ground.
    jharwinbarrozo
    20.5M
  • Net Portal
    Net Portal
    Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
    jharwinbarrozo
    43.0M
  • Power Net Portal
    Power Net Portal
    Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #power
    jharwinbarrozo
    11.4M
  • Generic Resistor
    Generic Resistor
    A generic fixed resistor ideal for rapid circuit topology development. Its footprint automatically adapts based on the selected package case code—supporting 0402, 0603, 0805, 1203, and many other standard SMD packages, as well as axial horizontal and vertical configurations. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0 ohm, 10 ohm, 100 ohm, 1.0k ohm, 10k ohm, 100k ohm, 1.0M ohm 1.1 ohm, 11 ohm, 110 ohm, 1.1k ohm, 11k ohm, 110k ohm, 1.1M ohm 1.2 ohm, 12 ohm, 120 ohm, 1.2k ohm, 12k ohm, 120k ohm, 1.2M ohm 1.3 ohm, 13 ohm, 130 ohm, 1.3k ohm, 13k ohm, 130k ohm, 1.3M ohm 1.5 ohm, 15 ohm, 150 ohm, 1.5k ohm, 15k ohm, 150k ohm, 1.5M ohm 1.6 ohm, 16 ohm, 160 ohm, 1.6k ohm, 16k ohm, 160k ohm, 1.6M ohm 1.8 ohm, 18 ohm, 180 ohm, 1.8K ohm, 18k ohm, 180k ohm, 1.8M ohm 2.0 ohm, 20 ohm, 200 ohm, 2.0k ohm, 20k ohm, 200k ohm, 2.0M ohm 2.2 ohm, 22 ohm, 220 ohm, 2.2k ohm, 22k ohm, 220k ohm, 2.2M ohm 2.4 ohm, 24 ohm, 240 ohm, 2.4k ohm, 24k ohm, 240k ohm, 2.4M ohm 2.7 ohm, 27 ohm, 270 ohm, 2.7k ohm, 27k ohm, 270k ohm, 2.7M ohm 3.0 ohm, 30 ohm, 300 ohm, 3.0K ohm, 30K ohm, 300K ohm, 3.0M ohm 3.3 ohm, 33 ohm, 330 ohm, 3.3k ohm, 33k ohm, 330k ohm, 3.3M ohm 3.6 ohm, 36 ohm, 360 ohm, 3.6k ohm, 36k ohm, 360k ohm, 3.6M ohm 3.9 ohm, 39 ohm, 390 ohm, 3.9k ohm, 39k ohm, 390k ohm, 3.9M ohm 4.3 ohm, 43 ohm, 430 ohm, 4.3k ohm, 43K ohm, 430K ohm, 4.3M ohm 4.7 ohm, 47 ohm, 470 ohm, 4.7k ohm, 47k ohm, 470k ohm, 4.7M ohm 5.1 ohm, 51 ohm, 510 ohm, 5.1k ohm, 51k ohm, 510k ohm, 5.1M ohm 5.6 ohm, 56 ohm, 560 ohm, 5.6k ohm, 56k ohm, 560k ohm, 5.6M ohm 6.2 ohm, 62 ohm, 620 ohm, 6.2k ohm, 62K ohm, 620K ohm, 6.2M ohm 6.8 ohm, 68 ohm, 680 ohm, 6.8k ohm, 68k ohm, 680k ohm, 6.8M ohm 7.5 ohm, 75 ohm, 750 ohm, 7.5k ohm, 75k ohm, 750k ohm, 7.5M ohm 8.2 ohm, 82 ohm, 820 ohm, 8.2k ohm, 82k ohm, 820k ohm, 8.2M ohm 9.1 ohm, 91 ohm, 910 ohm, 9.1k ohm, 91k ohm, 910k ohm, 9.1M ohm #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Capacitor
    Generic Capacitor
    A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF, 10pF, 100pF, 1000pF, 0.01uF, 0.1uF, 1.0uF, 10uF, 100uF, 1000uF, 10000uF 1.1pF, 11pF, 110pF, 1100pF 1.2pF, 12pF, 120pF, 1200pF 1.3pF, 13pF, 130pF, 1300pF 1.5pF, 15pF, 150pF, 1500pF, 0.015uF, 0.15uF, 1.5uF, 15uF, 150uF, 1500uF 1.6pF, 16pF, 160pF, 1600pF 1.8pF, 18pF, 180pF, 1800pF 2.0pF, 20pF, 200pF, 2000pF 2.2pF, 22pF, 220pF, 2200pF, 0.022uF, 0.22uF, 2.2uF, 22uF, 220uF, 2200uF 2.4pF, 24pF, 240pF, 2400pF 2.7pF, 27pF, 270pF, 2700pF 3.0pF, 30pF, 300pF, 3000pF 3.3pF, 33pF, 330pF, 3300pF, 0.033uF, 0.33uF, 3.3uF, 33uF, 330uF, 3300uF 3.6pF, 36pF, 360pF, 3600pF 3.9pF, 39pF, 390pF, 3900pF 4.3pF, 43pF, 430pF, 4300pF 4.7pF, 47pF, 470pF, 4700pF, 0.047uF, 0.47uF, 4.7uF, 47uF, 470uF, 4700uF 5.1pF, 51pF, 510pF, 5100pF 5.6pF, 56pF, 560pF, 5600pF 6.2pF, 62pF, 620pF, 6200pF 6.8pF, 68pF, 680pF, 6800pF, 0.068uF, 0.68uF, 6.8uF, 68uF, 680uF, 6800uF 7.5pF, 75pF, 750pF, 7500pF 8.2pF, 82pF, 820pF, 8200pF 9.1pF, 91pF, 910pF, 9100pF #generics #CommonPartsLibrary
    jharwinbarrozo
    1.5M
  • Generic Inductor
    Generic Inductor
    A generic fixed inductor suitable for rapid circuit topology development. The footprint automatically adapts based on the selected package, supporting standard SMD sizes (e.g., 0402, 0603, 0805) as well as well-known inductor packages such as SDR1806, PA4320, SRN6028, and SRR1260. Standard inductor values: 1.0 nH, 10 nH, 100 nH, 1.0 µH, 10 µH, 100 µH, 1.0 mH 1.2 nH, 12 nH, 120 nH, 1.2 µH, 12 µH, 120 µH, 1.2 mH 1.5 nH, 15 nH, 150 nH, 1.5 µH, 15 µH, 150 µH, 1.5 mH 1.8 nH, 18 nH, 180 nH, 1.8 µH, 18 µH, 180 µH, 1.8 mH 2.2 nH, 22 nH, 220 nH, 2.2 µH, 22 µH, 220 µH, 2.2 mH 2.7 nH, 27 nH, 270 nH, 2.7 µH, 27 µH, 270 µH, 2.7 mH 3.3 nH, 33 nH, 330 nH, 3.3 µH, 33 µH, 330 µH, 3.3 mH 3.9 nH, 39 nH, 390 nH, 3.9 µH, 39 µH, 390 µH, 3.9 mH 4.7 nH, 47 nH, 470 nH, 4.7 µH, 47 µH, 470 µH, 4.7 mH 5.6 nH, 56 nH, 560 nH, 5.6 µH, 56 µH, 560 µH, 5.6 mH 6.8 nH, 68 nH, 680 nH, 6.8 µH, 68 µH, 680 µH, 6.8 mH 8.2 nH, 82 nH, 820 nH, 8.2 µH, 82 µH, 820 µH, 8.2 mH #generics #CommonPartsLibrary
    jharwinbarrozo
    15.7k
  • Terminal
    Terminal
    An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
    natarius
  • RMCF0805JT47K0
    RMCF0805JT47K0
    47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlink
    jharwinbarrozo
    1.2M
  • 875105359001
    875105359001
    10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcan
    jharwinbarrozo
    1.2M
  • CTL1206FYW1T
    CTL1206FYW1T
    Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlink
    jharwinbarrozo
    1.1M

LM2596 Buck converter 5V

LM2596 Buck converter 5V thumbnail
This project is a DC-DC Buck converter based on the LM2596 IC. It is designed to step down the input voltage from 12V to a regulated output of 5V #Buck #LM2596 #project

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor

Qty 1

Digi-Key

$1.89–$3.76

LCSC

$2.96

Mouser

$3.70

Assets

LM2596-removebg-preview.png

LM2596-removebg-preview.png

LM2596-removebg-preview
LM2596 Buck converter 5V-removebg-preview.png

LM2596 Buck converter 5V-removebg-preview.png

LM2596 Buck converter 5V-removebg-previewThumbnail

Controls