Fiducial

AleksaZCodes·fiducial·examples/sensor-stick/hardware/generated/board.kicad_pcb

About the Fiducial PCB

Fiducial is an open source RP2040/RP2350 PCB design by AleksaZCodes, published on GitHub under the MIT license. It is a 2-layer board measuring 26 × 79 mm, with 25 components from 9 distinct parts.

Its main chip is the QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm, from the RP2040/RP2350 family. Other key parts include the SOT-223-3_TabPin2, SOIC-8_L5.3-W5.3-P1.27-LS8.0-BL and SENSOR-SMD_L3.0-W3.0-P1.00-BR. By type, the board carries 11 capacitors, 7 resistors, 4 ICs, 1 crystal, 1 connector and 1 diode.

It belongs with the sensors designs in this gallery.

From the project

Declare each fact once. Derive every artifact from it.

A USB-C stick that reports room temperature and humidity to a web page — a whole product, from one declaration, built with Fiducial and checked in its CI.

It is the platform's worked example: small and cheap (an RP2040, an AHT20 sensor, a WS2812B LED, a USB-C socket, 21 parts, about $5 of parts at five boards), but it carries every discipline a product has — a printed case, a routed board, firmware and a web page — and every one of them is derived from, or checked against, the same facts.

Fiducial, from the project README — From the project README

Main components on the Fiducial

QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm SOT-223-3_TabPin2 SOIC-8_L5.3-W5.3-P1.27-LS8.0-BL SENSOR-SMD_L3.0-W3.0-P1.00-BR

Fiducial bill of materials (BOM)

25 components, 9 distinct parts — part numbers from the project's BOM.

Qty	Part	Footprint	Refs
1	QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm	QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm	U1
1	SOT-223-3_TabPin2	SOT-223-3_TabPin2	U2
1	SOIC-8_L5.3-W5.3-P1.27-LS8.0-BL	SOIC-8_L5.3-W5.3-P1.27-LS8.0-BL	U3
1	SENSOR-SMD_L3.0-W3.0-P1.00-BR	SENSOR-SMD_L3.0-W3.0-P1.00-BR	U4
1	Crystal_SMD_3225-4Pin_3.2x2.5mm	Crystal_SMD_3225-4Pin_3.2x2.5mm	Y1
1	USB_C_Receptacle_HRO_TYPE-C-31-M-12	USB_C_Receptacle_HRO_TYPE-C-31-M-12	J1
1	LED_WS2812B_PLCC4_5.0x5.0mm_P3.2mm	LED_WS2812B_PLCC4_5.0x5.0mm_P3.2mm	D1
11	C_0603_1608Metric	C_0603_1608Metric	C1, C2, C3, C4, C5, C6, C7, C8 +3
7	R_0603_1608Metric	R_0603_1608Metric	R1, R2, R3, R4, R5, R6, R7

Fiducial design files

The KiCad project lives in the AleksaZCodes/fiducial repository on GitHub; these links point at the commit this page was built from.

Fiducial: common questions

What microcontroller does the Fiducial use?

The Fiducial is built around the QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm, from the RP2040/RP2350 family.

How big is the Fiducial PCB?

The Fiducial measures 26 × 79 mm, has 2 copper layers and is 1.6 mm thick.

How many components are on the Fiducial?

25 components, from 9 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.

Where can I download the Fiducial design files?

From the AleksaZCodes/fiducial repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.

Can I use the Fiducial design in my own project?

Yes, under the terms of its MIT license, which AleksaZCodes chose for the repository.

Can I test firmware for the Fiducial without the hardware?

Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug RP2040/RP2350 firmware against it before you order a PCB.