
Freesk8-NRF52-Dongle
FreeSK8/FreeSK8-NRF52-BLE-Hardware
KiCAD Design Files for NRF52 BLE Module - Based on Fanstel 840

Open-source platform for gut–computer interaction research with a wearable sensing system, real-time audio/haptic feedback, and tools for visualization, annotation, and analysis.
OpenGUT is an open-source printed circuit board by OpenGUT, from the OpenGUT/OpenGUT repository on GitHub. It is a 2-layer board of 45.3 × 45.1 mm with 63 parts on 106 nets, routed with 1,378 tracks and 146 vias.
It is built around the BT840F and SJ-3524-SMT-TR. Its parts include 27 capacitors, 11 resistors, 5 diodes, 5 connectors and 4 ICs. It belongs with the wearables boards of this library.
OpenGut is an open-source platform designed to enable research at the intersection of human-computer interaction (HCI), physiology, and interoception. It provides a complete end-to-end system for sensing, analyzing, and interacting with gut activity through a wearable device, software interface, and extensible documentation.
The gut plays a critical role in human physiology and cognition through the gut–brain axis. Despite growing interest in gut-based interaction, existing tools are fragmented, application-specific, and lack accessibility. OpenGut addresses this gap by providing a unified, reproducible, and extensible platform for researchers and developers.
OpenGut consists of three main components:
OpenGut supports multiple modes of operation:
OpenGut has been technically evaluated for:
OpenGut aims to lower the barrier to entry in gut-computer interaction research by providing a fully open, reproducible, and extensible platform for the community.
We welcome contributions from researchers, engineers, and designers interested in advancing gut-based interaction systems.
| Qty | Value | Footprint | References |
|---|---|---|---|
| 8 | 0.1 uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C1, C2, C9, C10, C12, C14, C15, C16 |
| 6 | 10 uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C3, C8, C11, C13, C24, C27 |
| 5 | R | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R1, R3, R5, R6, R11 |
| 4 | LED | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D1, D2, D3, D4 |
| 3 | 1 uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C20, C23, C26 |
| 2 | 0.01 uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C22, C25 |
| 2 | 100 nF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C17, C19 |
| 2 | 2.2 nF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C4, C6 |
| 2 | 2.2 uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C5, C7 |
| 2 | 4.7 k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R8, R10 |
| 2 | 470 | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R2, R4 |
| 1 | 10 k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R7 |
| 1 | 10k | Resistor_SMD:R_0603_1608Metric_Pad0.98x0.95mm_HandSolder | R9 |
| 1 | 1V8 | LT1763CDE-3.3_PBF:DFN-12_DE | U3 |
| 1 | 220 nF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C18 |
| 1 | 3V3 | LT1763CDE-3.3_PBF:DFN-12_DE | U4 |
| 1 | 4.7 uF | Capacitor_SMD:C_0603_1608Metric_Pad1.08x0.95mm_HandSolder | C21 |
| 1 | AMBIENT MIC | Sensor_Audio:Knowles_LGA-5_3.5x2.65mm | MK2 |
| 1 | BODY MIC | Sensor_Audio:Knowles_LGA-5_3.5x2.65mm | MK1 |
| 1 | BT840F | BT840F:XCVR_BT840F | U1 |
| 1 | DAC | Package_SO:TSSOP-20_4.4x6.5mm_P0.65mm | J3 |
| 1 | DEBUG OUT | FTSH-105-01-X-DV-K:SAMTEC_FTSH-105-01-X-DV-K | J4 |
| 1 | IMU | BHI360:XDCR_BHI360 | U2 |
| 1 | LOGO | Logos:AHLAB Logo | G*** |
| 1 | MODE | 430182043816:430182043816 | S2 |
| 1 | MicroSD | 104031-0811:MOLEX_104031-0811 | J2 |
| 1 | OFF | ON | JS102011SAQN:SW_JS102011SAQN | SW1 |
| 1 | P | LED_SMD:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | D5 |
| 1 | RESET | 430182043816:430182043816 | S3 |
| 1 | S2B-PH-K-S_LF__SN_ | S2B-PH-K-S_LF__SN_:JST_S2B-PH-K-S_LF__SN_ | J5 |
| 1 | SJ-3524-SMT | SJ-3524-SMT:CUI_SJ-3524-SMT | J1 |
| 1 | START/STOP | 430182043816:430182043816 | S1 |
The 59 most common of 63 parts.
It measures 45.3 × 45.1 mm and has 2 copper layers, 1 mm thick.
63 parts, built around the BT840F and SJ-3524-SMT-TR. 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 OpenGUT/OpenGUT repository on GitHub, at the commit this page was made from: the board is Hardware/OpenGUT -KiCad/OpenGUT.kicad_pcb and its schematic Hardware/OpenGUT -KiCad/OpenGUT.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 OpenGUT before reusing the design.

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