GNSS Alarm Clock
About the GNSS Alarm Clock PCB
GNSS Alarm Clock is an open source Microchip SAM PCB design by KrHaaland, published on GitHub. It is a 4-layer board measuring 80 × 50 mm, with 146 components from 40 distinct parts.
Its main chip is the ATSAMD51J19A-AUT, from the Microchip SAM family. Other key parts include the TPA2016D2RTJR, PRTR5V0U2X_C2827688, NPM1300-QEAA-R7, L86-M33 and RV-3028-C7. By type, the board carries 56 resistors, 34 LEDs, 28 capacitors, 14 ICs, 5 connectors and 5 switches.
It belongs with the rf & radio and power & battery designs in this gallery.
From the project
GNSS-synchronized alarm clock — custom SAMD51J20A board with nPM1300 Li-ion power (USB-C), offline timezone+DST from coordinates, LVGL 9 on a 428x142 TFT, WAV alarm tunes over USB, battery-backed RTC
Firmware for the custom SAMD51 alarm-clock board (Adafruit Metro M4 compatible), designed in HARDWARE/ (KiCad). Two board revisions share one firmware:
- v2 (current) — SAMD51J20A, nPM1300 PMIC with Li-ion charging and USB-C, LM3671 3.3 V + TPS61023 5 V boost, battery-backed RTC, MCU core on its internal buck regulator. See HARDWAREV2.md and ADR-0014/0015. Default build: metrom4j20. - v1 (prototype) — SAMD51J19A, LTC3226 + supercaps (design in HARDWAREOLD/). Build: adafruitmetrom4. The firmware detects the PMIC at runtime and degrades gracefully either way.
Main components on the GNSS Alarm Clock
GNSS Alarm Clock bill of materials (BOM)
146 components, 40 distinct parts — part numbers from the project's BOM.
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | TPA2016D2RTJR | TPA2016D2 | U1 |
| 1 | PRTR5V0U2X_C2827688 | PRTR5V0U2X | U2 |
| 1 | NPM1300-QEAA-R7 | nPM1300 | U3 |
| 1 | L86-M33 | L86-M33 | U4 |
| 1 | RV-3028-C7 | RV-3028-C7 | U5 |
| 1 | TPS61023DRLR | TPS61023 | U6 |
| 1 | LIS3DH | LGA-16_3x3mm_P0.5mm_LayoutBorder3x5y | U7 |
| 1 | 25Q128 | SOIC-8_5.3x5.3mm_P1.27mm | U8 |
| 1 | 74LVC1G17 | SOT-23-5 | U9 |
| 3 | IRLML6344TRPBF | IRLML6344 | U10, U11, U12 |
| 1 | LM3671MFX-3.3/NOPB | LM3671MFX-3.3 | U14 |
| 1 | ATSAMD51J19A-AUT | ATSAMD51J19_TQFP | U18 |
| 1 | 32.768 | Q13FC13500005 | X1 |
| 1 | USB4110GFA | USB4110-GF-A | J1 |
| 1 | SWD-Connector_3220-10-0100-00 | SWD-Connector | J3 |
| 1 | B8B-XH-A | B8B-XH-A | J4 |
| 2 | B2B-PH-K-S | B2B-PH-K-S | J6, J7 |
| 5 | TS-1187A-B-A-B | TS-1187A-B-A-B | SW1, SW2, SW3, SW4, SW5 |
| 34 | OR-PL020W | OR-PL020W | LED1, LED2, LED3, LED4, LED5, LED6, LED7, LED8 +26 |
| 1 | 2.2uH | VLCF4020T-2R2N1R7 | L1 |
Show 20 more
| Qty | Part | Footprint | Refs |
|---|---|---|---|
| 1 | 1µH | YXMAA0412-1R0M-ANP | L2 |
| 1 | 10uH | L_1008_2520Metric | L4 |
| 3 | 22µF | C_0805_2012Metric | C1, C3, C4 |
| 3 | 1uF | C_0805_2012Metric | C2, C5, C26 |
| 13 | 10uF | C_0805_2012Metric | C6, C7, C8, C9, C10, C11, C12, C16 +5 |
| 1 | 4.7uF | C_0805_2012Metric | C13 |
| 3 | 100nF | C_0805_2012Metric | C14, C15, C27 |
| 2 | 220uF | CP_Elec_6.3x5.7 | C18, C21 |
| 2 | 10pF | C_0805_2012Metric | C24, C25 |
| 1 | 10μF | C_0805_2012Metric | C29 |
| 4 | 1M | R_0805_2012Metric | R1, R8, R9, R10 |
| 2 | 100KΩ | R_0603_1608Metric | R4, R12 |
| 1 | 732KΩ | R_0603_1608Metric | R5 |
| 2 | 4.7K | R_0805_2012Metric | R6, R7 |
| 1 | 100k | R_0805_2012Metric | R13 |
| 3 | 470Ω | R_0805_2012Metric | R15, R54, R56 |
| 7 | 10KΩ | R_0805_2012Metric | R16, R18, R55, R57, R58, R63, R68 |
| 34 | 80Ω | R_0805_2012Metric | R20, R21, R22, R23, R24, R25, R26, R27 +26 |
| 1 | 1kΩ | R_0805_2012Metric | R66 |
| 1 | 100kΩ | R_0805_2012Metric | R67 |
GNSS Alarm Clock design files
The KiCad project lives in the KrHaaland/GNSS_Alarm_Clock repository on GitHub; these links point at the commit this page was built from.
GNSS Alarm Clock: common questions
What microcontroller does the GNSS Alarm Clock use?
The GNSS Alarm Clock is built around the ATSAMD51J19A-AUT, from the Microchip SAM family.
How big is the GNSS Alarm Clock PCB?
The GNSS Alarm Clock measures 80 × 50 mm, has 4 copper layers and is 1.6 mm thick.
How many components are on the GNSS Alarm Clock?
146 components, from 40 distinct parts, with part numbers taken from the project's own BOM. The full bill of materials is listed on this page.
Where can I download the GNSS Alarm Clock design files?
From the KrHaaland/GNSS_Alarm_Clock repository on GitHub, which has the KiCad layout, the schematic and the BOM; the links under Design files point to each one.
Can I use the GNSS Alarm Clock design in my own project?
The repository has no license, so all rights stay with KrHaaland. Use it as a reference, and ask the author before reusing the design.
Can I test firmware for the GNSS Alarm Clock without the hardware?
Yes. HardLabs builds a simulation of the board from its netlist and BOM, so you can run and debug Microchip SAM firmware against it before you order a PCB.
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