2 layers50.8 × 76.2 mm
Breadboard-1
bicknell/DCC-Mobile-Decoder
DCC Mobile Decoder Reference Implementation Hardware & Software
76 parts14
2 layers50.8 × 76.2 mm
Breadboard-2
bicknell/DCC-Mobile-Decoder14DCC Mobile Decoder Reference Implementation Hardware & Software
- Size
- 50.8 × 76.2 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 75
- Nets
- 58
- Pads
- 201
- Tracks, vias
- 409, 53
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 6 (file 20211014)
- Created
- 8 Nov 2022
- Updated
- 18 Mar 2024
Overview
Breadboard-2 is an open-source printed circuit board by bicknell, from the bicknell/DCC-Mobile-Decoder repository on GitHub. It is a 2-layer board of 50.8 × 76.2 mm with 75 parts on 58 nets, routed with 409 tracks and 53 vias.
It is built around the STM32G031F8P6, SE8633X2-HF and BSS138K, with the 1N5819WS, DTC143ZCA and PMV55ENEAR among its other parts. Its parts include 28 resistors, 14 diodes, 13 transistors, 8 capacitors and 5 connectors. It belongs with the STM32 boards of this library.
Main components
9
STM32G031F8P6
TSSOP-20-40℃~+85℃ 1.7V~3.6V 12bit 18 32 Bit 64KB 64MHz 8KB ARM Cortex-M0+ Built-in+External FLASH TSSOP-20 Microcontrollers (MCU/MPU/SOC) ROHSSTMicroelectronicsMicrocontrollers (MCU/MPU/SOC)
SE8633X2-HF
SOT-23-20℃~+85℃@(Ta) 1 1.8uA 200mA 3.3V 60V 700mV@(100mA) 70dB@(1kHz) Fixed、Adjustable Positive Short Circuit Protection、Thermal Shutdown SOT-23 Voltage Regulators - Linear, Low Drop Out (LDO) Regulators ROHSSeaward ElecVoltage Regulators - Linear, Low Drop Out (LDO) RegulatorsBSS138K
SOT-231 N-channel 1.5Ω@10V 1V 2.2pF 25pF 400mA 417mW 60V 650pC@4.5V 9.7pF N-Channel SOT-23 MOSFETs ROHSElecSuperMOSFETs
1N5819WS
SOD-3231 Independent 1A 25A 40V 500uA@40V 600mV@1A SOD-323 Schottky Diodes ROHSGuangdong HottechSchottky DiodesDTC143ZCA
SOT-23-55℃~+150℃ 1 NPN (Pre-Biased) 1.3V 100mA 12 200mW 250MHz 300mV@5mA,0.25mA 500mV@100uA,5V 50V 6.11kΩ 80 NPN SOT-23 Digital Transistors ROHSJiangsu Changjing Electronics Technology (CJ)Digital TransistorsPMV55ENEAR
SOT-23-55℃~+150℃ 1 N-channel 1.19W 19nC@10V 2.7V 3.1A 36pF 49pF 60V 60mΩ@10V 646pF N-Channel SOT-23 MOSFETs ROHSNexperiaMOSFETs
SSM3J356R,LF
SOT-23F1 P-Channel 1W 25pF 2A 2V 330pF 400mΩ@4V 40pF 60V 8.3nC@10V P-Channel SOT-23F MOSFETs ROHSToshibaMOSFETs
RC2512JK-7W100RL
2512-55℃~+155℃ 100Ω 200V 2W Thick Film Resistor ±200ppm/℃ ±5% 2512 Chip Resistor - Surface Mount ROHSYAGEOChip Resistor - Surface Mount
XL-3227SURSYGC
SMD-4P,3.2x2.7mm-30℃~+85℃ 120° 2.1V、2.1V 20mA 3.2mm x 2.7mm square LED 50mW、50mW 55mcd、135mcd 565nm~575nm、620nm~630nm 570nm、620nm Common Anode Red, Yellow Green Top-mount Water Clear SMD-4P,3.2x2.7mm LED Indication - Discrete ROHSXINGLIGHTLED Indication - Discrete
README
hardware/decoders/Wired-N-1A-2-1/README.mdWired-N-1A-2-1
About
The Wired-N-1A-2-1 design is a basic 1A N-Scale decoder based off the Breadboard-1 reference design.
- 1A Capacity
- 2 Functions (FOF, FOR)
- ICSP programming exposed via pads.
- Components on top side only enabling cheap fabrication.
3D Render
Actual size 9mm x 18mm:
Intended Use Case
Used for any hard wired N/Z scale application, from locomotives that do not support drop in decoders, to passenger car and caboose lighting operations.
Schematic
View the schematic: Wired-N-1A-2-1.pdf
Supporting CALCULATIONS.md discussions how component values were determined.
Schematic Walkthrough
Power Supply
Power from the two rails is fed into a bridge rectifier made up of four discrete diodes D11-D14. As DCC is a square wave, the output is nearly but not quite continuous DC power with low ripple. That power is split off to drive the motor and functions directly, labeled as Vdrive. A linear regulator U11 is used to generate +5v for the micro-processor, and has two support capacitors.
The project requirements for this design are to operate from 6v to 30v of input.
Micro-controller
A PIC18F06Q40 processor is used in this design due to it's avaialbility in a 3mm x 3mm VQFN-20 package. PIC processors require minimal support components. C21 is a local bypass capacitor that is placed closed to the power pins. C23 and R11 form a hold up circuit for MCLR which must be kept high during normal operation. If MCLR drops, the chip will reset.
Particular notes on this part:
- This design does not use a Vref pin.
H-Bridge
The H-Bridge controls the current to the motor. It is driven by a PWM signal generated by the micro-controller. The software generates 4 PWM signals, P1A-P1D, which are used to control speed and direction.
The H-bridge is simply 4 high power MOSFETs arranged in an H configuration. This design uses two discrete dual MOSFET chips each with 1 PNP and 1NPN MOSFET, which is a common arrangement. Resistors are placed on the gate inputs to prevent inrush from damaging the micro-controller.
External diodes are omitted on this design to save space, the body diode of the MOSFET must do the job.
In order to calculate BackEMF, a 100nf capacitor C31 is added to reduce signal noise. The resistors R35 and R36 then reduce the voltage to an appropriate level for the analog input of the micro-controller. By monitoring this voltage the micro-controller can calculate the load.
Functions
This design supports functions F0F, F0R, F1-F6.
Functions F0F, F0R, and F1-F6 are designed to be connected to external device in a "common anode" configuration.
Vdrive power is provided as a common anode source at both ends of the board. The MOSFET connects to ground when turned on by the micro-processor. A resistor is provided on the gate of each MOSFET to manage inrush current.
External Connectivity
MA & MB are the two motor connection solder pads.
RL & RR are the left and right rail solder pads.
F0F, F0R, & F0-F6 are the function solder pads.
CA are the Common Anode solder pads.
MCLR, +5, GND, PGD, PGD make up the ISCP connection points.
Parts
75| Qty | Value | Footprint | References |
|---|---|---|---|
| 10 | 330R | Resistor_SMD:R_0805_2012Metric | R55, R56, R61, R62, R71, R72, R73, R74, R75, R76 |
| 8 | 3K | Resistor_SMD:R_0805_2012Metric | R59, R81, R82, R83, R84, R85, R86, R87 |
| 8 | White LED | LED_SMD:LED_0805_2012Metric | D61, D62, D81, D82, D83, D84, D85, D86 |
| 7 | BSS138K | Package_TO_SOT_SMD:SOT-23 | Q31, Q71, Q72, Q73, Q74, Q75, Q76 |
| 6 | 10K | Resistor_SMD:R_0805_2012Metric | R31, R32, R51, R52, R53, R54 |
| 5 | 1N5819 | Diode_SMD:D_SOD-323 | D11, D12, D13, D14, D15 |
| 4 | 10uF | Capacitor_SMD:C_0805_2012Metric | C12, C13, C51, C52 |
| 2 | 01x06 | Connector_PinHeader_2.54mm:PinHeader_1x06_P2.54mm_Vertical | J1, J2 |
| 2 | 100nF | Capacitor_SMD:C_0805_2012Metric | C21, C22 |
| 2 | 22K | Resistor_SMD:R_0805_2012Metric | R57, R58 |
| 2 | DTC143ZCA | Package_TO_SOT_SMD:SOT-23 | Q53, Q54 |
| 2 | PMV55ENEAR | Package_TO_SOT_SMD:SOT-23 | Q55, Q56 |
| 2 | SSM3J356R,LF | Package_TO_SOT_SMD:SOT-23 | Q51, Q52 |
| 1 | 01x02 | Connector_PinHeader_2.54mm:PinHeader_1x02_P2.54mm_Vertical | JP41 |
| 1 | 01x05 | Connector_PinHeader_2.54mm:PinHeader_1x05_P2.54mm_Horizontal | J3 |
| 1 | 01x05S | Connector_PinSocket_2.54mm:PinSocket_1x05_P2.54mm_Horizontal | J5 |
| 1 | 01x07 | Connector_PinHeader_2.54mm:PinHeader_1x07_P2.54mm_Vertical | J4 |
| 1 | 100R | Resistor_SMD:R_2512_6332Metric | R41 |
| 1 | 4.7uF | Capacitor_SMD:C_0805_2012Metric | C23 |
| 1 | 4R7 | Resistor_SMD:R_0805_2012Metric | R11 |
| 1 | DNP | Capacitor_THT:CP_Radial_D10.0mm_P2.50mm_P5.00mm | C11 |
| 1 | R/G LED | LED_SMD:LED_RGB_1210 | D87 |
| 1 | SE8633X2-HF | Package_TO_SOT_SMD:SOT-23 | U11 |
| 1 | STM32G031F8P6 | Package_SO:TSSOP-20_4.4x6.5mm_P0.65mm | U21 |
The 71 most common of 75 parts.
Questions
How big is the Breadboard-2 PCB?
It measures 50.8 × 76.2 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Breadboard-2 use?
75 parts, built around the STM32G031F8P6, SE8633X2-HF, BSS138K and 1N5819WS. 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 Breadboard-2 KiCad files?
From the bicknell/DCC-Mobile-Decoder repository on GitHub, at the commit this page was made from: the board is hardware/reference/Breadboard-2/Breadboard-2.kicad_pcb and its schematic hardware/decoders/Atlas-N-1A-2-GP40-1/Atlas-N-1A-2-GP40-1.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Breadboard-2 design in my own project?
Its repository states no licence, so its author keeps all rights: ask bicknell before reusing the design.
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