arnv15/HelixCustom Devboard
Devboard is an open-source printed circuit board by arnv15, from the arnv15/Helix repository on GitHub. It is a 2-layer board of 37 × 75 mm with 49 parts on 71 nets, routed with 437 tracks and 28 vias.
It is built around the RP2040, ESP32-C3-WROOM-02-H4 and W25Q128JVSIQ, with the AP2112K-3.3TRG1 and SK6812MINI-E among its other parts. Its parts include 20 capacitors, 9 resistors, 5 connectors, 4 ICs and 4 switches. It belongs with the microcontroller boards boards and the ESP32, RP2040 and RISC-V boards of this library.
My take on an Arduino — a custom development board built around the Raspberry Pi RP2040, designed from schematic through to a fully routed, manufacturable PCB.
Helix is a hand-designed development board built to learn the fundamentals of circuit design. It's built around a full RP2040 microcontroller, with a voltage regulator, USB-C connector, crystal oscillator, external flash memory, two rows of GPIO pins (ESP-style, breadboard-friendly), and external UART pins for connecting to a motor controller.
The longer-term goal of the project is to use Helix as the MCU for an SO-101 robotic arm, which is controlled over a UART connection.
See JOURNAL.md for the full build log, including design decisions, DRC fixes, and lessons learned along the way.
Designing the schematic
Finished schematic design
Starting the PCB layout
Routing the main components
Finished routing both layers
Fixing DRC errors
Cleaning up silkscreen and warnings
Adding a filled ground zone
Part selection and BOM
Parts were sourced using the BOM below, with manufacturing and assembly done through JLCPCB (many of the components are too small to hand-solder without a hot plate).
| Designator | Footprint | Qty | Comment |
|---|---|---|---|
| C22,C8,C9,C5,C3,C7,C6,C4,C19,C10,C17,C20 | C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | 12 | 0.1uF |
| J3,J5 | PinHeader_1x18_P2.54mm_Vertical | 2 | Conn_01x18_Pin |
| U3 | SOIC-8_5.3x5.3mm_P1.27mm | 1 | W25Q128JVS |
| R2,R1 | R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | 2 | 5.1K |
| Y1 | Crystal_SMD_3225-4Pin_3.2x2.5mm_HandSoldering | 1 | 12 MHz |
| C21,C18,C1,C2 | C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | 4 | 10uF |
| SW4 | SW_Push_SPST_NO_Alps_SKRK | 1 | ESP_BOOT |
| R5,R6 | R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | 2 | 1K |
| U5 | SOT95P285X140-5N | 1 | AP2112K-3.3TRG1 |
| J4 | PinHeader_1x03_P2.54mm_Vertical | 1 | Conn_01x03_Pin |
| R4,R3 | R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | 2 | 27 |
| C16,C15 | C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | 2 | 33pF |
| U4 | ESP32-C3-WROOM-02 | 1 | ESP32-C3-WROOM-02 |
| SW3 | SW_Push_SPST_NO_Alps_SKRK | 1 | ESP_RESET |
| R7,R8,R11 | R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | 3 | 10K |
| J2 | PinHeader_1x03_P2.54mm_Vertical | 1 | UART_Conn |
| C23,C11 | C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | 2 | 1uF |
| SW2 | SW_Push_SPST_NO_Alps_SKRK | 1 | Run |
| U1 | QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm | 1 | RP2040 |
| SW1 | SW_Push_SPST_NO_Alps_SKRK | 1 | FLASH_RESET |
| J1 | USB_C_Receptacle_HRO_TYPE-C-31-M-12 | 1 | USB_C_Receptacle_USB2.0_14P |
| D2,D1 | SK6812MINI-E_fixed | 2 | SK6812MINI-E |
Full BOM available at Production/BOM.csv.
| Qty | Value | Footprint | References |
|---|---|---|---|
| 12 | 0.1uF | Capacitor_SMD:C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | C3, C4, C5, C6, C7, C8, C9, C10, C17, C19, C20, C22 |
| 4 | 10uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C2, C18, C21 |
| 4 | MountingHole | MountingHole:MountingHole_3.2mm_M3 | H1, H2, H3, H4 |
| 3 | 10K | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R7, R8, R11 |
| 2 | 1K | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R5, R6 |
| 2 | 1uF | Capacitor_SMD:C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | C11, C23 |
| 2 | 27 | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R3, R4 |
| 2 | 33pF | Capacitor_SMD:C_0402_1005Metric_Pad0.74x0.62mm_HandSolder | C15, C16 |
| 2 | 5.1K | Resistor_SMD:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R1, R2 |
| 2 | Conn_01x18_Pin | Connector_PinHeader_2.54mm:PinHeader_1x18_P2.54mm_Vertical | J3, J5 |
| 2 | SK6812MINI-E | footprints:SK6812MINI-E_fixed | D1, D2 |
| 1 | 12 MHz | Crystal:Crystal_SMD_3225-4Pin_3.2x2.5mm_HandSoldering | Y1 |
| 1 | AP2112K-3.3TRG1 | AP2112K-3.3TRG1:SOT95P285X140-5N | U5 |
| 1 | Conn_01x03_Pin | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J4 |
| 1 | ESP32-C3-WROOM-02 | RF_Module:ESP32-C3-WROOM-02 | U4 |
| 1 | ESP_BOOT | Button_Switch_SMD:SW_Push_SPST_NO_Alps_SKRK | SW4 |
| 1 | ESP_RESET | Button_Switch_SMD:SW_Push_SPST_NO_Alps_SKRK | SW3 |
| 1 | FLASH_RESET | Button_Switch_SMD:SW_Push_SPST_NO_Alps_SKRK | SW1 |
| 1 | RP2040 | Package_DFN_QFN:QFN-56-1EP_7x7mm_P0.4mm_EP3.2x3.2mm | U1 |
| 1 | Run | Button_Switch_SMD:SW_Push_SPST_NO_Alps_SKRK | SW2 |
| 1 | UART_Conn | Connector_PinHeader_2.54mm:PinHeader_1x03_P2.54mm_Vertical | J2 |
| 1 | USB_C_Receptacle_USB2.0_14P | Connector_USB:USB_C_Receptacle_HRO_TYPE-C-31-M-12 | J1 |
| 1 | W25Q128JVS | Package_SO:SOIC-8_5.3x5.3mm_P1.27mm | U3 |
It measures 37 × 75 mm and has 2 copper layers, 1.6 mm thick.
49 parts, built around the RP2040, ESP32-C3-WROOM-02-H4, W25Q128JVSIQ and AP2112K-3.3TRG1. 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 arnv15/Helix repository on GitHub, at the commit this page was made from: the board is Production/Devboard.kicad_pcb and its schematic Production/Devboard.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Its repository states no licence, so its author keeps all rights: ask arnv15 before reusing the design.
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