2 layers25 × 20 mm
RP2040-Decoder
gab-k/RP2040-Decoder
Cost effective DIY DCC Decoder for model railroad locomotives
57 parts131
4 layers25 × 20 mm
RP2040-Decoder
gab-k/RP2040-Decoder131Cost effective DIY DCC Decoder for model railroad locomotives
- Size
- 25 × 20 mm
- Copper layers
- 4
- Thickness
- 1.61 mm
- Parts
- 68
- Nets
- 68
- Pads
- 232
- Tracks, vias
- 426, 114
- Pours
- 6
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 22 Aug 2021
- Updated
- 20 Feb 2026
Overview
RP2040-Decoder is an open-source printed circuit board by gab-k, from the gab-k/RP2040-Decoder repository on GitHub. It is a 4-layer board of 25 × 20 mm with 68 parts on 68 nets, routed with 426 tracks and 114 vias.
It is built around the RP2040, BDR6133 and W25Q64JVSSIQ, with the MIC5200-3.3YS, SI1308EDL and 1N5819WS among its other parts. Its parts include 21 connectors, 18 capacitors, 15 resistors, 5 transistors and 4 ICs. It belongs with the RP2040 boards of this library.
Main components
9
RP2040
LQFN-56(7x7)12bit 133MHz 30 LQFN-56(7x7) Microcontrollers (MCU/MPU/SOC) ROHSRaspberry PiMicrocontrollers (MCU/MPU/SOC)
BDR6133
ESOP-8-40℃~+85℃ 1 2.7V~5.5V 2.8A 4.8A 50nA 510mΩ ESOP-8 Brushed DC Motor Drivers ROHSBardeen Micro.Brushed DC Motor Drivers
W25Q64JVSSIQ
SOIC-8-208mil-40℃~+85℃ 100,000 cycles 10uA 133MHz 150ms@(64KB) 2.7V~3.6V 20 Years 3ms 64Mbit SPI SOIC-8-208mil NOR FLASH ROHSWinbondNOR FLASH
MIC5200-3.3YS
SOT-223-40℃~+125℃ 1 100mA 100uV 26V 3.3V 350mV@(100mA) 350uA 70dB Fixed Over Current Protection、Over Temperature Protection Positive SOT-223 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSMicrochip TechnologyVoltage Regulators - Linear, Low Drop Out (LDO) Regulators
SI1308EDL
SC-70-3-55℃~+150℃ 1 N-channel 1.4nC@10V 1.5A 1.5V 105pF 11pF 132mΩ@10V 23pF 30V 400mW N-Channel SOT-323 MOSFETs ROHSVishay IntertechnologyMOSFETs
1N5819WS
SOD-3231 Independent 1A 25A 40V 500uA@40V 600mV@1A SOD-323 Schottky Diodes ROHSGuangdong HottechSchottky Diodes
KMB24F
MBS-55℃~+125℃ 2A 40V 50A 550uA 700mV@2A Single-Phase Rectifier MBS Bridge Rectifiers ROHSFUXINSEMIBridge Rectifiers
X322512MSB4SI
SMD3225-4P-40℃~+85℃ 12MHz 20pF 80Ω Crystal Oscillator ±10ppm ±20ppm SMD3225-4P Crystals ROHSYXCCrystals
YTS1T0162AWJ00
SMD,4.2x3.3mmTactile SwitchesYIYUAN
README
README.mdRP2040-Decoder
Designed to be a low-cost, open-source alternative to commercial DCC decoders, it utilizes the Raspberry Pi RP2040 dual-core microcontroller. The decoder features DCC protocol decoding and command interpretation alongside motor control in a compact 25x20 mm form factor.
Key Features
- DCC Signal Decoding: Interrupt-based edge detection with full packet/protocol decoding.
- Motor Control: 128 speed steps with configurable acceleration/deceleration ramping and v_min/v_mid/v_max; closed-loop control for consistent motor speed under varying load conditions.
- Flexible I/O: 4x transistor-switched outputs and 6x additional GPIOs; all of them PWM capable.
- CV Configuration: Function mapping and programming track support.
- Standards Compliance: Implements the most important NMRA (S-9.1, S-9.2.x) and RCN (210, 212, 216) DCC standards.
- Compact Form Factor: 25x20 mm board size.
- Integrated Documentation: Comprehensive GitHub Pages documentation covering hardware theory and software implementation.
Architecture Overview
The system uses each of the two ARM Cortex-M0+ cores for separate tasks:
- Core 0: Signal Processing & Management
- DCC edge detection and packet decoding.
- Configuration Variable (CV) management using persistent flash storage.
- Service Mode (Programming Track) logic and acknowledgment pulse generation.
- Core 1: Motion Control
- PID Controller: A discrete-time PID motor controller implementation utilizing based on a bilinear transform formula.
- Back-EMF Feedback: ADC sampling during PWM-off cycles.
- Adaptive Control: Gain scheduling for $K_P$ and a startup controller (feed-forward) to overcome static friction.
Hardware Revisions
USB Version
Optimized for ease of use; supports UF2 drag-and-drop flashing and serial logging.
Legacy Version
Revision without USB, one sided assembly, flashed via SWD.
Getting Started
To get started, you will first need the hardware. The different options for acquiring a board are outlined here.
For the software, you have a few options: you can either build it from source or use the ready-to-flash binaries built by the CI pipeline on each release. Flashing the firmware can be done via SWD or, if you are using the USB hardware version, simply by dragging and dropping the file using your regular file explorer.
License
- Software: MIT License
- Hardware: CERN Open Hardware Licence Version 2 - Permissive
Parts
68| Qty | Value | Footprint | References |
|---|---|---|---|
| 9 | 100n | Capacitor_SMD:C_0402_1005Metric | C2, C6, C7, C10, C11, C12, C14, C15, C16 |
| 9 | Conn_01x01 | TestPoint:TestPoint_Pad_D1.5mm | J5, J6, J7, J8, J9, J10, J11, J12, J13 |
| 9 | Conn_01x01 | TestPoint:TestPoint_Pad_D2.0mm | J1, J2, J4, J14, J15, J16, J17, J18, J21 |
| 5 | 1k | Resistor_SMD:R_0402_1005Metric | R4, R5, R10, R13, R15 |
| 5 | Si1308EDL | Package_TO_SOT_SMD:SOT-323_SC-70 | Q1, Q2, Q3, Q4, Q5 |
| 4 | 10u | Capacitor_SMD:C_0603_1608Metric | C3, C5, C17, C18 |
| 4 | 6k8 | Resistor_SMD:R_0402_1005Metric | R8, R9, R12, R14 |
| 3 | 10u | Capacitor_SMD:C_0402_1005Metric | C8, C9, C13 |
| 2 | 10p | Capacitor_SMD:C_0402_1005Metric | C1, C4 |
| 2 | 27 | Resistor_SMD:R_0402_1005Metric | R6, R7 |
| 2 | 5k1 | Resistor_SMD:R_0402_1005Metric | R2, R3 |
| 2 | Conn_01x01 | TestPoint:TestPoint_Pad_1.5x1.5mm | J19, J20 |
| 1 | 1N5819WS | Diode_SMD:D_SOD-323_HandSoldering | D1 |
| 1 | 200 | Resistor_SMD:R_0402_1005Metric | R11 |
| 1 | BDR6133 | RP2040-Decoder_Additional_Footprints:SOIC-8-1EP_3.9x4.9mm_P1.27mm_EP2.41x3.3mm_ThermalVias | U4 |
| 1 | DNF | Resistor_SMD:R_0402_1005Metric | R1 |
| 1 | KMB24F | Package_TO_SOT_SMD:TO-269AA | D2 |
| 1 | LED | LED_SMD:LED_0603_1608Metric | D3 |
| 1 | MIC5200-3.3YS | Package_TO_SOT_SMD:SOT-223 | U1 |
| 1 | RP2040 | Package_DFN_QFN:QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm | U3 |
| 1 | USB_C_Receptacle_USB2.0_16P | Connector_USB:USB_C_Receptacle_GCT_USB4105-xx-A_16P_TopMnt_Horizontal | J3 |
| 1 | W25Q64JVSSIQ | RP2040-Decoder_Additional_Footprints:SOIC-8_5.23x5.23mm_P1.27mm | U2 |
| 1 | X322512MSB4SI | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm | Y1 |
| 1 | YTS1T0162AWJ00 | RP2040-Decoder_Additional_Footprints:SW_Push_1P1T_NO_Vertical_Wuerth_434133025816 | SW1 |
More from gab-k/RP2040-Decoder
1Similar boards
- 2 layers99.1 × 99 mm
XDuinoRail Debug
chatelao/xDuinoRail-Decoder
The friendly decoder development plattform for model railroad tinkers.
170 partsAGPL-3.0 - 6 layers30 × 20.1 mm
XDuinoRails Thor M
xDuinoRails/xDuinoRails_Thor
Make a Seeed XIAO board a mtc21 decoder, all the electronics needed is on this little board: - mtc21/plux16 compatible connector - DC Motor - 2x Functions - DCC / DCC-ACK / RailCom
46 parts1 - 2 layers17.5 × 38 mm
Tps6292
ABaboshin/IoTrains
The existing systems in the market are either with old roots (DCC) or not opensource (Märklin). More then that they were built over 20 years ago and therefore have historical restrictions.
19 partsMIT - 2 layers90 × 67 mm
- 2 layers65 × 45 mm
- 2 layers21 × 51 mm
Orphkicad
adammakesthingsdev/Orpheus-Pico-Kicad
Kicad files and JLCPCB production gerbers for Orpheus Pico
43 parts13 - 2 layers154.7 × 79.5 mm
Illuminati
Enderman8843/illuminati
illuminati is a precession drafting triangle with many inbuilt microprocessor and wifi
66 parts1 - 2 layers358.8 × 134.9 mm
Rheneium
Enderman8843/Rhenium
Rhenium is a Keyboard that is powered by RP2040 microprocessor that uses a USB-C,
213 parts1
Questions
How big is the RP2040-Decoder PCB?
It measures 25 × 20 mm and has 4 copper layers, 1.61 mm thick.
What parts does the RP2040-Decoder use?
68 parts, built around the RP2040, BDR6133, W25Q64JVSSIQ and MIC5200-3.3YS. 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.
Where can I download the RP2040-Decoder KiCad files?
From the gab-k/RP2040-Decoder repository on GitHub, at the commit this page was made from: the board is KiCad/USB/RP2040-Decoder.kicad_pcb and its schematic KiCad/Legacy/RP2040-Decoder.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the RP2040-Decoder design in my own project?
Its repository states no licence, so its author keeps all rights: ask gab-k before reusing the design.