6 layers17 × 10.9 mm
6 layers17 × 10.9 mm
DCC / Railcom decoder (NEM651, single sided), WS28xx
- Size
- 17 × 10.9 mm
- Copper layers
- 6
- Thickness
- 0.8 mm
- Parts
- 53
- Nets
- 51
- Pads
- 169
- Tracks, vias
- 382, 61
- Pours
- 5
- Routed
- Yes
- KiCad
- KiCad 10.0 (file 20260206)
- Created
- 31 May 2026
- Updated
- 9 Jul 2026
Overview
D24 is an open-source printed circuit board by git4dcc, from the git4dcc/RTB_D24 repository on GitHub, published under the Apache-2.0 licence. It is a 6-layer board of 17 × 10.9 mm with 53 parts on 51 nets, routed with 382 tracks and 61 vias.
It is built around the AVR64DA32-E/PT, PMZB200UNEYL and BAS3007ARPPE6327HTSA1, with the BC847BDW1 and BC857BDW1 among its other parts. Its parts include 25 resistors, 9 connectors, 6 capacitors, 6 transistors and 3 ICs.
Main components
5
AVR64DA32-E/PT
TQFP-32(7x7)-40℃~+125℃ 1.8V~5.5V 10bit 12bit 24MHz 27 512Byte 64KB 8 Bit 8KB AVR Built-in FLASH TQFP-32(7x7) Microcontrollers (MCU/MPU/SOC) ROHSMicrochip TechnologyMicrocontrollers (MCU/MPU/SOC)
PMZB200UNEYL
SOT-883-3-55℃~+150℃ 1 N-channel 1.4A 2.7nC@4.5V 250mΩ@4.5V 30V 350mW 89pF 950mV 9pF SOT-883-3 MOSFETs ROHSNexperiaMOSFETs
BAS3007ARPPE6327HTSA1
Bridge rectifier 30V/900mA in SOT143-4 package.Infineon TechnologiesUncategorised
BC847BDW1
SOT-363-55℃~+150℃ 100MHz 100mA 150 2 NPN 250mV 380mW 45V 5uA 6V NPN SOT-363 Bipolar (BJT) ROHSonsemiBipolar (BJT)BC857BDW1
SOT-363-55℃~+150℃ 100MHz 100mA 2 PNP 220 250mW 45V 4uA 5V 650mV PNP SOT-363 Bipolar (BJT) ROHSonsemiBipolar (BJT)
README
README.mdRTB_D24
My Homebrew D24 is a single-sided DIY mobile decoder featuring a NEM-651 connector. While it shares the exact same dimensions as the D16, it offers additional AUX channels and supports WS28xx LED connections. It is fully designed for integration into the RTB digital control ecosystem.
User Guides
- User Guide - DE
- User Guide - EN
The decoder has the following features,
- NEM-651 connector
- DCC
- DCC-A automatic logon
- DCC-R protocol extension
- Service Mode Programming
- Railcom
- Channel 1/2
- POM, xPOM
- DYN: Speed, QoS, Track-voltage, Motor-current, AUX-current, Temp, Distance travelled
- Single sided
- Dimension: 17 x 11 mm
- 7-20V track voltage
- heartbeat LED
- adjustable max motor current (default 300mA)
- adjustable max AUX current (default 500mA)
- over temp protection
- Function output: LV/LR/AUX1/AUX2 (dimmable, 1.4kHz) open drain
- Function output: AUX3/AUX4/AUX5/AUX6/AUX7 logic level (5V)
- AUX3/AUX4 can be configured to drive WS28xx chips
- optional external buffer capacitor (max. 1500uF)
- <10mA idle power consumption
- Firmware update over main tracks via DCC-R protocol
Hardware
The current PCB layout uses SMD footprints with 0.5mm pitch and mainly 0402 parts. Reflow soldering is recommended, handsoldering will be difficult.
Note: The '5V zone' silk text can be misleading as the above test point is not 5V source but rather the UPDI interface.
PCB
- 6-layer PCB, FR4, 17 x 11 x 0.8mm (single sided)
- CPU: AVR64DA32
- Motor bridge: DRV8231
- Connector: NEM-651
Kicad
Dependency
:yellow_circle: Requires my Kicad project library RTB_SamacSys in the same directory tree.
Firmware
Filename structure: { pcb }{ code }{ version }.hex
Example: D16F0001.hex
| Description | |
|---|---|
| pcb | Name of matching hardware (D24) |
| code | Type of code contained (R=rom, B=bootloader, F=flash, U=bld update, P=UPDI factory code) |
| version | Release version (####) |
Images
| top | bottom |
|---|---|
 |  |
YouTube
Some YouTubes to see the D24 decoder in action.
This project is intended for hobby use only and is distributed in accordance with the Apache License 2.0 agreement.
Parts
53| Qty | Value | Footprint | References |
|---|---|---|---|
| 6 | 10k | Resistor_SMD:R_0402_1005Metric | R11, R13, R15, R18, R19, R20 |
| 5 | Conn_01x01 | RTB:Solder_Pad_1.0x1.0mm | J1, J3, J4, J5, J6 |
| 4 | 33k | Resistor_SMD:R_0402_1005Metric | R7, R8, R10, R12 |
| 4 | 4.7k | Resistor_SMD:R_0402_1005Metric | R1, R4, R5, R6 |
| 4 | PMZB200UNEYL | RTB:PMZB200UNEYL | Q2, Q3, Q5, Q6 |
| 3 | 10u/6.3V | Capacitor_SMD:C_0402_1005Metric | C1, C3, C13 |
| 3 | 220k | Resistor_SMD:R_0402_1005Metric | R17, R34, R35 |
| 2 | 2.2 | Resistor_SMD:R_0402_1005Metric | R9, R22 |
| 2 | 9.1k | Resistor_SMD:R_0402_1005Metric | R36, R37 |
| 1 | 100 | Resistor_SMD:R_0603_1608Metric | R14 |
| 1 | 1k | Resistor_SMD:R_0402_1005Metric | R21 |
| 1 | 1u | Capacitor_SMD:C_0402_1005Metric | C6 |
| 1 | 1u/35V | Capacitor_SMD:C_0603_1608Metric | C4 |
| 1 | 22 | Resistor_SMD:R_0402_1005Metric | R3 |
| 1 | 22u/25V | Capacitor_SMD:C_0805_2012Metric | C7 |
| 1 | 3.3k | Resistor_SMD:R_0402_1005Metric | R2 |
| 1 | AVR-64DA32 | Package_DFN_QFN:VQFN-32-1EP_5x5mm_P0.5mm_EP3.1x3.1mm | U1 |
| 1 | BAS3007ARPPE6327HTSA1 | RTB:BF998215 | D3 |
| 1 | BC847BDW1 | Package_TO_SOT_SMD:SOT-666 | Q1 |
| 1 | BC857BDW1 | Package_TO_SOT_SMD:SOT-666 | Q4 |
| 1 | DRV8231ADSGR | RTB:SON50P200X200X80-9N | IC1 |
| 1 | LED pink | LED_SMD:LED_0402_1005Metric | D1 |
| 1 | NCP730BMT500TBG | Package_SON:WSON-6-1EP_2x2mm_P0.65mm_EP1x1.6mm_ThermalVias | IC2 |
| 1 | NEM651 | Connector_PinHeader_1.27mm:PinHeader_1x08_P1.27mm_Horizontal | J2 |
| 1 | NSR20F40NXT5G | RTB:NSR20F40NXT5G | D2 |
| 1 | TestPoint | TestPoint:TestPoint_Pad_D1.0mm | TP1 |
| 1 | WS28xx GND | RTB:Solder_Pad_1.0x1.0mm | J8 |
| 1 | WS28xx data | RTB:Solder_Pad_1.0x1.0mm | J7 |
| 1 | WS28xx power | RTB:Solder_Pad_1.0x1.0mm | J9 |
Questions
How big is the D24 PCB?
It measures 17 × 10.9 mm and has 6 copper layers, 0.8 mm thick.
What parts does the D24 use?
53 parts, built around the AVR64DA32-E/PT, PMZB200UNEYL, BAS3007ARPPE6327HTSA1 and BC847BDW1. 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 D24 KiCad files?
From the git4dcc/RTB_D24 repository on GitHub, at the commit this page was made from: the board is D24.kicad_pcb and its schematic D24.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the D24 design in my own project?
Its repository publishes it under the Apache-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).
Similar boards
- 6 layers14 × 8 mm
- 6 layers15.3 × 11.4 mm
- 4 layers50.9 × 15.5 mm
- 4 layers76 × 11 mm
- 6 layers15.2 × 9.5 mm
- 4 layers160.8 × 12 mm
- 4 layers17.3 × 15.3 mm
