Raspberry Pi 5 HAT+: EMC2303 controller for 3 case fans + GNSS (UART/PPS) breakout. KiCad 10, CERN-OHL-S v2.
HAT+ is an open-source printed circuit board by cvaldess, from the cvaldess/Rpi3FanHatPlus repository on GitHub, published under the CERN-OHL-S-2.0 licence. It is a 4-layer board of 65 × 56.5 mm with 41 parts on 53 nets, routed with 305 tracks and 108 vias.
It is built around the EMC2303-1-KP-TR, AT24CS64-MAHM-T and AT24CS64-SSHM-B, with the HRC0603F4701ENTN, HRC0603F3901ENTN and CC0603KRX7R9BB104 among its other parts. Its parts include 14 resistors, 6 connectors, 4 capacitors, 3 ICs and 3 transistors. It belongs with the interfaces and adapters and radio and wireless boards of this library.
Raspberry Pi 5 HAT+ that drives the three fans of a case with a Microchip EMC2303 fan controller and breaks out the Pi's UART and a PPS input for a GNSS module (J2).
Status: revision 1, not yet manufactured or tested.
0x2E, ALERT on GPIO5).| Ref | Function | Pinout |
|---|---|---|
| J1 | Raspberry Pi 40-pin GPIO (Samtec HLE-120-02-F-DV-BE-A, bottom-entry SMT socket) | Standard Raspberry Pi header |
| J2 | GNSS module to Raspberry Pi (2×6, 2.54 mm, right angle) | 1: PPS → GPIO18 · 3: +5 V · 5: GPIO14 TXD (Pi → GNSS RX) · 7: GPIO15 RXD (GNSS TX → Pi) · 9: GND · others not connected |
| J3 | 12 V input (1×2, 2.54 mm) | 1: +12 V · 2: GND — not keyed, check polarity |
| J4 | Fan 3, 2-wire (1×2, 2.54 mm) | 1: +12 V · 2: Fan − (switched) |
| J5, J6 | Fan 1, Fan 2, 4-pin PWM (Molex 47053) | 1: GND · 2: +12 V · 3: Tach · 4: PWM |
GNSS signals on J2 are 3.3 V logic: the module's UART and PPS must not exceed 3.3 V.
| Signal | GPIO | Notes |
|---|---|---|
| I²C SDA / SCL | GPIO2 / GPIO3 | EMC2303 at 0x2E |
| Fan controller ALERT | GPIO5 | Active low, 4.7 kΩ pull-up |
| UART TXD / RXD | GPIO14 / GPIO15 | GNSS module (J2) |
| GNSS PPS | GPIO18 | |
| HAT+ ID EEPROM | GPIO0 / GPIO1 |
Example config.txt lines:
dtparam=i2c_arm=on
enable_uart=1
dtoverlay=pps-gpio,gpiopin=18The HATPlus/fab/ folder contains:
Rpi3FanHatPlus-gerbers.zip: Gerber (4 copper layers, masks, paste, silkscreen, outline) and Excellon drill files.HAT+-BOM-PCBWay.csv: bill of materials with manufacturer part numbers and LCSC codes.HAT+-CPL-PCBWay.csv: component placement file, in millimetres, top side only.The files are prepared for PCB fabrication and assembly (PCBA) at PCBWay. Board: 4 layers, 1.6 mm, ENIG recommended, minimum track/space 0.15 mm, minimum drill 0.4 mm.
KiCad 10 project in HATPlus/ (HAT+.kicad_pro); project
footprint libraries in HATPlus/libs/ and libs/.
The schematic review, design changes, footprints and fabrication outputs were done with Konnect, an AI-assisted PCB design tool for KiCad 10, driven by Anthropic's Claude through Claude Code.
Based on the Raspberry Pi HAT+ KiCad template by Helge Wurst (CERN-OHL-S v2).
Copyright © 2024 Helge Wurst (HAT+ template), © 2026 CValdesS.
This source describes Open Hardware and is licensed under the CERN-OHL-S v2 (LICENSE). You may redistribute and modify this source and make products using it under the terms of the CERN-OHL-S v2. This source is distributed WITHOUT ANY EXPRESS OR IMPLIED WARRANTY, INCLUDING OF MERCHANTABILITY, SATISFACTORY QUALITY AND FITNESS FOR A PARTICULAR PURPOSE. Please see the CERN-OHL-S v2 for applicable conditions.
Source location: https://github.com/cvaldess/Rpi3FanHatPlus
| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 4.7K | Resistor_SMD:R_0603_1608Metric | R5, R6, R7, R8, R9, R10, R11 |
| 4 | 3.9k | Resistor_SMD:R_0603_1608Metric | R1, R2, R3, R4 |
| 4 | MountingHole 3.2mm | MountingHole:MountingHole_3.2mm_M3_DIN965 | H1, H2, H3, H4 |
| 3 | 100n 50V | Capacitor_SMD:C_0603_1608Metric | C1, C2, C3 |
| 2 | 2.2K | Resistor_SMD:R_0603_1608Metric | R12, R13 |
| 2 | 2N7002 | Package_TO_SOT_SMD:SOT-23 | Q4, Q5 |
| 2 | TestPoint_Alt | TestPoint:TestPoint_Pad_D1.0mm | GND1, WP1 |
| 1 | 0.5A | Fuse:Fuse_1206_3216Metric | F1 |
| 1 | 10K | Resistor_SMD:R_0603_1608Metric | R14 |
| 1 | 10u 50V | Capacitor_SMD:C_1206_3216Metric | C4 |
| 1 | 12V | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Horizontal | J3 |
| 1 | AO3400A | Package_TO_SOT_SMD:SOT-23 | Q6 |
| 1 | AT24CS64-MAHM | Package_DFN_QFN:DFN-8-1EP_3x2mm_P0.5mm_EP1.3x1.5mm | U2 |
| 1 | AT24CS64-SSHM | Package_SO:SOIC-8_3.9x4.9mm_P1.27mm | U1 |
| 1 | EMC2303-1-KP-TR | libs:TQFN-12_L4.0-W4.0-P0.80-BL-EP2.1_PasteGrid | U3 |
| 1 | FAN1 | Connector:FanPinHeader_1x04_P2.54mm_Vertical | J5 |
| 1 | FAN2 | Connector:FanPinHeader_1x04_P2.54mm_Vertical | J6 |
| 1 | Fan3 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Horizontal | J4 |
| 1 | GNSS | Connector_PinHeader_2.54mm:PinHeader_2x06_P2.54mm_Horizontal | J2 |
| 1 | LOGO | oshw-logo-outlined-black | G*** |
| 1 | LOGO | libs:pcway_logo | G*** |
| 1 | RPi_40Pin | Connector_Samtec_Reverse:Samtec_HLE-120-02-xxx-DV-BE-A_2x20_P2.54mm_Horizontal_Reverse | J1 |
| 1 | SS14 | easyeda2kicad:SMA_L4.3-W2.6-LS5.1-RD | D1 |
| 1 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | A0 |
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It measures 65 × 56.5 mm and has 4 copper layers, 1.62 mm thick.
41 parts, built around the EMC2303-1-KP-TR, AT24CS64-MAHM-T, AT24CS64-SSHM-B and HRC0603F4701ENTN. The full list of its parts is on this page, with links to each part's symbol and footprint where PCBKit's library has them.
From the cvaldess/Rpi3FanHatPlus repository on GitHub, at the commit this page was made from: the board is HATPlus/HAT+.kicad_pcb and its schematic HATPlus/HAT+.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Its repository publishes it under the CERN-OHL-S-2.0 licence: you may reuse it on that licence's terms (keep the author's notice, and for a copyleft licence share your changes alike).