

Bigdot
librelab::Big Dot board
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 54
- Nets
- 44
- Pads
- 204
- Tracks, vias
- 513, 57
- Pours
- 5
- Routed
- Yes
- KiCad
- KiCad 7 (file 20221018)
- Created
- 19 Feb 2021
- Updated
- 2 Mar 2025
Overview
Bigdot is an open-source printed circuit board by unixjazz, from the unixjazz/bigdot repository on GitHub. It is a 2-layer board with 54 parts on 44 nets, routed with 513 tracks and 57 vias.
It is built around the MCP73831, RFM95W-915S2 and DMG2301L, with the FBMH3216HM221NT among its other parts. Its parts include 15 capacitors, 11 resistors, 7 connectors, 4 ICs and 3 diodes. It belongs with the SAM D and SAM boards of this library.
Main components
4MCP73831
UncategorisedMicrochip TechnologyRFM95W-915S2
LCC-16_16X16mmLCC-16_16X16mm New Arrivals ROHSHopeRF Micro-electronicsUncategorisedDMG2301L
SOT-23-55℃~+150℃ 1 P-Channel 1.2V 1.5W 150mΩ@2.5V 20V 3A 5.5nC@4.5V P-Channel SOT-23 MOSFETs ROHSDiodes IncorporatedMOSFETsFBMH3216HM221NT
1206-40℃~+125℃ 1 20mΩ 220Ω@100MHz 4A ±30% 1206 Ferrite Beads ROHSTaiyo YudenFerrite Beads
README
README.mdlibrelab::Big Dot

A SAML21-based board kit for your environmental sensing projects!
Description
In this repository you will find the design and firmware files for librelab::Big Dot, our libre hardware kit for low-energy LoRa applications. The content in this repo is organized in the following way:
├── arduino-core (support files)
├── board (main board design)
├── board-ext (extension board design)
├── bootloader (firmware files)
├── docs (user documentation)
└── examples (applications)Installation
Arduino support
To install the support files for librelab::Big Dot on Arduino, just include the following line in the field 'Additional Boards Manager URL' (under 'Preferences' menu) of your Arduino IDE:
https://unixjazz.org/pub/software/package_librelab_index.jsonWe are using the Arduino SAMD core (v1.6), but forked and modified by MattairTech to add support for the chip SAML21. You will need Arduino 1.8.13 or superior to use this core with our board.
This core has been tested on Linux (64-bit), Windows 10, and Mac OS 10.15 (64-bit only). If you need further instructions on how to install the Arduino core, follow this link.
RIOT-OS support
If Arduino is not suitable for your project, you can use better alternatives. All the paths lead to the same destination (when it comes to our finitude as species), but some are more direct than others. You may want to use RIOT-OS! Our board is supported and the support can be found here.
To use RIOT-OS with librelab::Big Dot, just pass its name to make:
$ BOARD=bigdot make allIf you are new to RIOT-OS, make sure to follow the tutorials.
Prototyping
If you do not have a Big Dot at hand, you can use a SAML21 Xplained board for testing purposes. The information on how to flash the bootloader we use can be found in the bootloader directory. For your convenience, we also included pre-compiled firmware files in this repository as well.
We recommend the usage of the UF2 bootloader included in the bootloaders directory: bigdot-uf2.bin.
Project info
Big Dot was developed at librelab, School of Data Science (UVA) with funding from the "Network Public Spaces" (NPS) project between 2020-2021. Since then, it has been run as an independent project by Open Hardware enthusiasts.
License
All the documentation is released as CC-BY-4.0-International. All the hardware code is released under CERN-OHL-v2 Strongly Reciprocal. All software code is released under GPL v3, unless marked otherwise on the source file headers. See LICENSE and AUTHORS files for further information.
Big Dot is Open Source Hardware-certified.

Happy hw hacking!
Parts
54| Qty | Value | Footprint | References |
|---|---|---|---|
| 5 | 100n | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C3, C5, C12, C13, C15 |
| 3 | SolderJumper_2_Open | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP1, JP3, JP4 |
| 2 | 10k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R6, R11 |
| 2 | 10u | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C10, C14 |
| 2 | 12pF | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C6, C9 |
| 2 | 1M | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R3, R4 |
| 2 | 1k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R1, R7 |
| 2 | 2.2u | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C1, C2 |
| 2 | 4.7k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R8, R9 |
| 2 | Conn_01x14 | Connector_PinHeader_2.54mm:PinHeader_1x14_P2.54mm_Vertical | J4, J6 |
| 1 | 10K | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R10 |
| 1 | 10u | Inductor_SMD:L_1206_3216Metric_Pad1.42x1.75mm_HandSolder | L1 |
| 1 | 10uF | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C4 |
| 1 | 1u | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C11 |
| 1 | 2.2k | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R5 |
| 1 | 32.768kHz | Crystal:Crystal_SMD_MicroCrystal_CC4V-T1A-2Pin_5.0x1.9mm_HandSoldering | Y1 |
| 1 | 330 | Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolder | R2 |
| 1 | 4,7uF | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C7 |
| 1 | 4.7uF | Capacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolder | C8 |
| 1 | ATSAML21E18B-AUT | Package_QFP:TQFP-32_7x7mm_P0.8mm | U4 |
| 1 | Conn_01x02 | Connector_JST:JST_PH_S2B-PH-K_1x02_P2.00mm_Horizontal | J3 |
| 1 | Conn_ARM_JTAG_SWD_10 | Connector_PinHeader_2.54mm:PinHeader_2x05_P2.54mm_Vertical | J1 |
| 1 | Conn_Coaxial | fp:Connector_Coaxial_SMA_edge_combined | J7 |
| 1 | DMG2301L | Package_TO_SOT_SMD:SOT-23 | Q1 |
| 1 | D_Schottky | Diode_SMD:D_1206_3216Metric_Pad1.42x1.75mm_HandSolder | D1 |
| 1 | FBMH3216HM221NT | Inductor_SMD:L_1206_3216Metric_Pad1.42x1.75mm_HandSolder | FB1 |
| 1 | LED | LED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolder | D2 |
| 1 | MCP73831 | Package_TO_SOT_SMD:SOT-23-5 | U2 |
| 1 | RFM95W-915S2 | fp:RFM95W | U3 |
| 1 | SW_Push | Button_Switch_SMD:SW_SPST_PTS645 | RESET |
| 1 | TPS7A05 | Package_TO_SOT_SMD:SOT-23_Handsoldering | U1 |
| 1 | USB_B_Micro | Connector_USB:USB_Micro-B_Molex-105017-0001 | J2 |
| 1 | antenna | Connector_Wire:SolderWire-0.75sqmm_1x01_D1.25mm_OD2.3mm | J8 |
| 1 | batt | LED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolder | D3 |
| 1 | jumper-open | Jumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mm | JP2 |
The 49 most common of 54 parts.
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Questions
What parts does the Bigdot use?
54 parts, built around the MCP73831, RFM95W-915S2, DMG2301L and FBMH3216HM221NT. 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 Bigdot KiCad files?
From the unixjazz/bigdot repository on GitHub, at the commit this page was made from: the board is board/board.kicad_pcb and its schematic board-ext/wifi_shield.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Bigdot design in my own project?
Its repository states no licence, so its author keeps all rights: ask unixjazz before reusing the design.