2 layers159.5 × 30 mm
Type f
google/mozc-devices
Circuit diagrams and firmware source code for Gboard DIY keyboards
25 parts3kApache-2.0
2 layers22.4 × 52.2 mm
Saml21-narrow dbu v1
brucebiotech/dbucmsis-dap compatible multi-target debug adapter
- Size
- 22.4 × 52.2 mm
- Copper layers
- 2
- Thickness
- 1.6 mm
- Parts
- 25
- Nets
- 48
- Pads
- 149
- Tracks, vias
- 361, 46
- Pours
- 2
- Routed
- Yes
- KiCad
- KiCad 8.0 (file 20240108)
- Created
- 8 Jun 2025
- Updated
- 27 Nov 2025
Overview
Saml21-narrow dbu v1 is an open-source printed circuit board by brucebiotech, from the brucebiotech/dbu repository on GitHub. It is a 2-layer board of 22.4 × 52.2 mm with 25 parts on 48 nets, routed with 361 tracks and 46 vias.
It is built around the A3B-10PA-2DS(51). Its parts include 10 capacitors, 6 connectors, 4 resistors, 4 ICs and 1 diode. It belongs with the SAM D and SAM boards of this library.
Main components
1README
hardware/README.mdtarget hardware
The target hardware is yours to design. It just needs to incorporate the SAML21 and botstrap programming connector somewhere, e.g as done in the schematic and PCB in the hardware folder.
Your board
.-------------------------------------------------------.
| Your CPUs here... |
| |
---. .------. cmsis-dap |
USB|---|SAML21|------+-----+-----+-----+-----+-----. |
---' | |-. | | | |
| `------' | |0 |1 ... |n |
| SWD| | .-+-. -+-. .-+-. |
---. | | |CPU| |CPU| |CPU| |
--|------' | | | | | | | |
---' | `-+-' `-+-' `-+-' |
| | | | | |
| `----+-----+-----+-----+-----+-----' |
| uarts |
`-------------------------------------------------------'dbu bootstrap
An option would be to put a standard 10-way debug pin header on the target board.
As this connector is not used in the normal development workflow of the target, this is an example hardware for bootstrapping that saves the cost and real estate of adding the 10-pin header.
The bootstrap dbu is connected to a traget using an edge connector on the target's PCB. The particular details of this connection are detailed as J4 on the KiCad schematic and PCB hardware files.
You then need a second, bootstrap dbu to attach to the dbu on the target, e.g.
Note that this board has a break-away section for the AVX edge connector. Usually you would detach this section and connect the two parts with the 10-pin right angle pin header.
Parts
25| Qty | Value | Footprint | References |
|---|---|---|---|
| 7 | 1uF | fizkit-fpdu-v1a:0402 | C2, C3, C4, C5, C6, C9, C10 |
| 2 | 0.1uF | fizkit-fpdu-v1a:0402 | C7, C8 |
| 2 | 5k1 | io:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R3, R4 |
| 2 | TLV75733 | fizkit-fpdu-v1a:SOT23-5 | U2, U3 |
| 1 | 009159010801906 | io:blocks-edge-10-socket | J6 |
| 1 | 10uF | fizkit-fpdu-v1a:0402 | C1 |
| 1 | 1k | io:R_0402_1005Metric_Pad0.72x0.64mm_HandSolder | R2 |
| 1 | 680k | fizkit-fpdu-v1a:0402 | R1 |
| 1 | A3B-10PA-2DS(51) | project:PinHeader_2x05_P2.00mm_Vertical | J5 |
| 1 | A3B-10PA-2DS(51) | project:PinHeader_2x05_P2.00mm_Horizontal | J7 |
| 1 | Bootstrap SWD - D.N.P. | project:2X5-SMD-UNSHROUDED | J2 |
| 1 | PRTR5V0U2-S | fizkit-fpdu-v1a:SOT143B | U4 |
| 1 | SAML21E17 | fizkit-fpdu-v1a:TQFP32-08 | U1 |
| 1 | SWD-EDGE | io:blocks-edge-10-plug | J4 |
| 1 | USB_C_Receptacle_USB2.0 | io:USB_C_Receptacle_GCT_USB4105-xx-A_16P_TopMnt_Horizontal | J1 |
| 1 | ~ | io:LED_0603_1608Metric_Pad1.05x0.95mm_HandSolder | LED1 |
Questions
How big is the Saml21-narrow dbu v1 PCB?
It measures 22.4 × 52.2 mm and has 2 copper layers, 1.6 mm thick.
What parts does the Saml21-narrow dbu v1 use?
25 parts, built around the A3B-10PA-2DS(51). 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 Saml21-narrow dbu v1 KiCad files?
From the brucebiotech/dbu repository on GitHub, at the commit this page was made from: the board is hardware/saml21-narrow-dbu-v1.kicad_pcb and its schematic hardware/saml21-narrow-dbu-v1.kicad_sch. PCBKit opens the board in the browser, with nothing to install.
Can I use the Saml21-narrow dbu v1 design in my own project?
Its repository states no licence, so its author keeps all rights: ask brucebiotech before reusing the design.
Similar boards
- 2 layers113.5 × 95.1 mm
Sweep high
davidphilipbarr/Sweep
Sweep - a small promicro based keyboard inspired by the Ferris.
25 parts2.1k - 2 layers75 × 30 mm
- 2 layers58.4 × 114.3 mm
PicoPedal
hackclub/OnBoard
💡 Join 1,000 teenagers and make your first PCB with a $100 grant!
25 parts915 - 2 layers54 × 15 mm
Xyp gpib
xyphro/UsbGpib
Versatile, cheap and portable USB to GPIB converter (USBTMC class based)
25 parts690MIT - 2 layers50 × 76 mm
- 2 layers237.5 × 102.9 mm
Storage
jes/scamp-cpu
A homebrew 16-bit CPU with a homebrew Unix-like-ish operating system.
25 parts301Unlicense - 2 layers43.3 × 21 mm
