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2 layersBigdot, the printed circuit board in 3D

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

4

README

README.md

librelab::Big Dot

These birds are chirping (CSS) with LoRa!

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:

bash
├── 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:

text
https://unixjazz.org/pub/software/package_librelab_index.json

We 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:

bash
$ BOARD=bigdot make all

If 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.

big-dot-cert-oshw

Happy hw hacking!

Parts

54
QtyValueFootprintReferences
5100nCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC3, C5, C12, C13, C15
3SolderJumper_2_OpenJumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mmJP1, JP3, JP4
210kResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR6, R11
210uCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC10, C14
212pFCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC6, C9
21MResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR3, R4
21kResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR1, R7
22.2uCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC1, C2
24.7kResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR8, R9
2Conn_01x14Connector_PinHeader_2.54mm:PinHeader_1x14_P2.54mm_VerticalJ4, J6
110KResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR10
110uInductor_SMD:L_1206_3216Metric_Pad1.42x1.75mm_HandSolderL1
110uFCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC4
11uCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC11
12.2kResistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR5
132.768kHzCrystal:Crystal_SMD_MicroCrystal_CC4V-T1A-2Pin_5.0x1.9mm_HandSolderingY1
1330Resistor_SMD:R_1206_3216Metric_Pad1.30x1.75mm_HandSolderR2
14,7uFCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC7
14.7uFCapacitor_SMD:C_1206_3216Metric_Pad1.33x1.80mm_HandSolderC8
1ATSAML21E18B-AUTPackage_QFP:TQFP-32_7x7mm_P0.8mmU4
1Conn_01x02Connector_JST:JST_PH_S2B-PH-K_1x02_P2.00mm_HorizontalJ3
1Conn_ARM_JTAG_SWD_10Connector_PinHeader_2.54mm:PinHeader_2x05_P2.54mm_VerticalJ1
1Conn_Coaxialfp:Connector_Coaxial_SMA_edge_combinedJ7
1DMG2301LPackage_TO_SOT_SMD:SOT-23Q1
1D_SchottkyDiode_SMD:D_1206_3216Metric_Pad1.42x1.75mm_HandSolderD1
1FBMH3216HM221NTInductor_SMD:L_1206_3216Metric_Pad1.42x1.75mm_HandSolderFB1
1LEDLED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolderD2
1MCP73831Package_TO_SOT_SMD:SOT-23-5U2
1RFM95W-915S2fp:RFM95WU3
1SW_PushButton_Switch_SMD:SW_SPST_PTS645RESET
1TPS7A05Package_TO_SOT_SMD:SOT-23_HandsolderingU1
1USB_B_MicroConnector_USB:USB_Micro-B_Molex-105017-0001J2
1antennaConnector_Wire:SolderWire-0.75sqmm_1x01_D1.25mm_OD2.3mmJ8
1battLED_SMD:LED_1206_3216Metric_Pad1.42x1.75mm_HandSolderD3
1jumper-openJumper:SolderJumper-2_P1.3mm_Open_RoundedPad1.0x1.5mmJP2

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.