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Colby Custom Azumo MIP Smartwatch PCB

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by Andy E

Custom BLE 5.4 smartwatch PCB engineered for the Azumo 11049-06 front-lit reflective MIP LCD, with Qi wireless charging, 150 mAh LiPo battery, haptic vibration motor, and 3-axis tap sensor

smartwatchazumoblenrf52840qi-wireless-chargingpcbwayfusion-360aiflow
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Andy E Publish Colby Azumo 11049-06 BLE Smartwatch project page, README gallery, and page.json bindings e9d1779 13d ago

Colby Azumo 11049-06 BLE Smartwatch PCB

Custom ultra-low-power Bluetooth 5.4 Low Energy (BLE) smartwatch mainboard engineered in Autodesk Fusion 360 with Adom AI Flow to fit inside the Colby 3D watch housing (33.405 mm x 38.361 mm recessed pocket shelf) and mate with zero stress to the official Azumo 11049-06 1.28-inch front-lit reflective Memory-in-Pixel (MIP) display.

Plain-Language Architecture Summary

  1. Exact Display Footprint & Symmetrical Torx Mounting Tabs: The main rectangular PCB body measures strictly 27.46 mm x 30.30 mm to match the Azumo 11049-06 display module footprint. Four symmetrical, mirrored corner mounting tabs with 1.40 mm plated through-holes (H1 to H4) extend to 33.00 mm x 37.41 mm overall and align to the exact 29.7058 mm x 34.1132 mm center-to-center pitch of the four 1 mm mounting posts in the watch housing.
  2. Zero-Stress FPC Ribbon Alignment: Both bottom-contact 0.5 mm pitch ZIF connectors (J1: Hirose FH34SRJ-10S-0.5SH-50 10-pin MIP LCD connector at X = 16.072 mm, Y = 31.210 mm; J2: Hirose FH34SRJ-4S-0.5SH-50 4-pin frontlight connector at X = 8.267 mm, Y = 31.210 mm) are positioned directly on the horizontal centerlines and fold radii of the Azumo display flex tails so both ribbons plug straight in with zero sideways bend or stress.
  3. Wireless Charging & Largest Compatible LiPo Battery: A TDK WR222230-26M8-G (22.0 mm x 22.0 mm x 0.75 mm, 26.8 uH) Qi receiver coil feeds a Texas Instruments BQ51003YFPR Qi v1.2 wireless receiver (5.0 V regulated output) and a Microchip MCP73831T-2ACI-OT linear LiPo charger configured for 100 mA CC/CV charging (R2 = 10.0 kOhm) into a 150 mAh 302025 standard LiPo pouch cell (ASR00003, 20.0 mm x 25.0 mm x 3.0 mm).
  4. Always-On BLE 5.4 Core, Haptics & Tap Control: A Raytac MDBT50Q-1MV2 (Nordic nRF52840 BLE 5.4 SoC with integrated ceramic chip antenna and 1 MB Flash / 256 KB RAM) drives the 2 MHz SPI display bus, reads hardware single/double-tap interrupts over 400 kHz I2C from the STMicroelectronics LIS2DW12TR 3-axis accelerometer (0.38 uA ultra-low-power mode), dims the frontlight LED via low-side MOSFET Q1 (BSS138LT1G + R5 = 39 Ohm), and pulses the Vybronics VZ30C1T8460002L coin vibration motor via low-side MOSFET Q2 (BSS138LT1G) with a BAT54JFILM Schottky flyback clamp (D1).
  5. PCBWay Manufacturing & Black-on-Black Aesthetics: Designed to PCBWay standard design rules (0.15 mm / 0.15 mm min trace/space, 0.30 mm min via drill, 1.0 mm board thickness, 1 oz outer copper, Matte Black solder mask, and Black silkscreen).

1. Live Autodesk Fusion 360 2D Routed & Poured PCB Layout

Live Autodesk Fusion 360 2D PCB Layout showing 100% routed traces, dual GND copper pours, and 20-segment stepped outline

Figure 1: Live Autodesk Fusion 360 2D PCB Editor view of ColbyAzumoSmartwatch showing 100% routed copper (0 airwires, 0 DRC errors), top and bottom GND copper pours (555.5 mm²), and the 20-segment stepped outline with four 1.4 mm Torx mounting holes (H1 to H4).

2. High-Resolution 2D Board Layout Export

High-resolution 2D board layout export showing top red copper, bottom blue copper, 112 vias, and 40 placed components

Figure 2: Direct 300 DPI board export from Fusion Electronics showing all 40 placed components, zero-stress bottom-edge FPC connectors J1 and J2, antenna keepout along the top edge for U1 (MDBT50Q-1MV2), and readable silkscreen labels.

3. Live Autodesk Fusion 360 Schematic Layout (5 Functional Blocks)

Live Autodesk Fusion 360 Schematic Editor showing the 5 functional blocks: Core, Input, Output, Monitor, and Test

Figure 3: Live Autodesk Fusion 360 Schematic Editor view of ColbyAzumoSmartwatch organized into 5 clean functional blocks (Core, Input, Output, Monitor, and Test) with custom chip-outline symbols and explicit net labels.

4. High-Resolution Full Schematic Sheet Export

High-resolution schematic sheet export of the 5 functional circuit blocks

Figure 4: Full-sheet schematic export (ColbyAzumoSmartwatch.sch) detailing the BLE 5.4 core (U1), Qi wireless receiver (U2 + L_COIL1), 100 mA LiPo charger (U5 + BT1), 3.3 V low-Iq LDO (U3), Azumo MIP LCD and frontlight connectors (J1, J2), haptic motor driver (M1, Q2, D1), tap sensor (U4), and test points (TP1 to TP9).

5. Complete 3D Populated Watch Assembly (Isometric Top & Display Stack)

Isometric 3D render of the fully populated smartwatch PCB assembly with translucent Azumo 11049-06 MIP display and FPC ribbons

Figure 5: Complete 3D populated assembly (Colby_Azumo_Smartwatch_Full_Assembly.step / .glb) showing the Azumo 11049-06 MIP display module seated above the matte-black PCB with both polyimide flex cables looping smoothly into J1 and J2.

6. Complete 3D Populated Watch Assembly (Underside: 302025 LiPo & Qi Receiver Coil)

Underside 3D render of the fully populated smartwatch assembly showing the 302025 LiPo pouch cell and 22x22mm TDK wireless charging coil

Figure 6: Underside view of the complete 3D assembly showing the 150 mAh 302025 LiPo battery (20.0 mm x 25.0 mm x 3.0 mm with Kapton collar) and the 22.0 mm x 22.0 mm TDK WR222230-26M8-G wireless charging receiver coil nested cleanly inside the watch pocket envelope.

7. DC Copper Current Density Solve (adom-fields)

adom-fields DC current density distribution map showing 20 A/mm2 peak current density against the 60 A/mm2 limit

Figure 7: Finite-volume DC current density map (adom-fields) across VBAT (120 mA), V_WCHG (100 mA), and VDD_3V3 (40 mA). Peak copper current density is 20.0 A/mm², providing a 3x safety margin below the 60.0 A/mm² limit with 0.000 W copper Joule loss.

8. Coupled 3D Electro-Thermal Steady-State Map & Transient SPICE Waveforms

adom-fields coupled 3D thermal steady-state map showing +21 C peak rise in still air during active Qi wireless charging

Figure 8: Coupled 3D steady-state thermal map (adom-fields) under simultaneous Qi wireless charging and active operation (0.22 W total IC dissipation). Peak temperature rise is +21.0 °C in still air (+15.0 °C in moving air), well inside the +25.0 °C budget.

Selected Bill of Materials (All 8 Part Groups Approved)

Ref MPN Manufacturer Function / Package Qty DigiKey PN Mouser PN LCSC PN
U1 MDBT50Q-1MV2 Raytac (Nordic) nRF52840 BLE 5.4 Module (10.5 x 15.5 mm) 1 1914-MDBT50Q-1MV2CT-ND 993-MDBT50Q-1MV2 C5118826
U2 BQ51003YFPR Texas Instruments Qi v1.2 5V Wireless Power Receiver (DSBGA-28) 1 296-37313-1-ND 595-BQ51003YFPR C86784
U3 TLV75533PDBVR Texas Instruments 3.3V 500mA Low-Iq (25 uA) LDO (SOT-23-5) 1 296-50411-2-ND 595-TLV75533PDBVR C404027
U4 LIS2DW12TR STMicroelectronics 3-Axis Tap/Double-Tap Accelerometer (LGA-12) 1 497-17014-1-ND 511-LIS2DW12TR C189615
U5 MCP73831T-2ACI-OT Microchip 100 mA Single-Cell LiPo Charger (SOT-23-5) 1 MCP73831T-2ACI-OTCT-ND 579-MCP73831T-2ACIOT C424093
J1 FH34SRJ-10S-0.5SH-50 Hirose 10-Pin 0.5mm ZIF Display FPC Connector 1 HF110CT-ND 798-FH34SRJ10S05SH50 C283651
J2 FH34SRJ-4S-0.5SH-50 Hirose 4-Pin 0.5mm ZIF Frontlight FPC Connector 1 HF104CT-ND 798-FH34SRJ4S0.5SH50 C283649
L_COIL1 WR222230-26M8-G TDK 26.8 uH Qi Receiver Coil (22.0 x 22.0 x 0.75 mm) 1 445-173602-ND 810-WR222230-26M8-G C2990942
BT1 ASR00003 TinyCircuits 150 mAh 3.7V 302025 LiPo Battery (20 x 25 x 3 mm) 1 1568-1457-ND 474-ASR00003 C2985411
M1 VZ30C1T8460002L Vybronics 8 mm Coin Haptic Vibration Motor (8.0 x 3.0 mm) 1 1670-1021-ND 490-VZ30C1T8460002L C495932
Q1, Q2 BSS138LT1G onsemi 50V 200mA N-Ch MOSFET (SOT-23-3) 2 BSS138LT1GOSCT-ND 863-BSS138LT1G C8492
D1 BAT54JFILM STMicroelectronics 40V 300mA Schottky Flyback Diode (SOD-323) 1 497-3328-1-ND 511-BAT54JFILM C8598
C1, C2 GRM155R61A106ME44D Murata 10 uF 10V X5R Ceramic Capacitor (0402) 2 490-10474-1-ND 81-GRM155R61A106ME44 C15849
C3..C7 GCM155R71H104KE02D Murata 100 nF 50V X7R Ceramic Capacitor (0402) 5 490-5915-1-ND 81-GCM155R71H104KE2D C1525
R1, R2, R6 CRCW040210K0FKED Vishay Dale 10.0 kOhm 1% Thick Film Resistor (0402) 3 541-10.0KLCT-ND 71-CRCW040210K0FKED C25744
R3, R4 CRCW04024K70FKED Vishay Dale 4.70 kOhm 1% I2C Pull-Up Resistor (0402) 2 541-4.70KLCT-ND 71-CRCW04024K70FKED C25900
R5 CRCW040239R0FKED Vishay Dale 39.0 Ohm 1% Frontlight LED Resistor (0402) 1 541-39.0LCT-ND 71-CRCW040239R0FKED C25111
R7 CRCW04021M00FKED Vishay Dale 1.00 MOhm 1% EXTMODE Pull-Down (0402) 1 541-1.00MLCT-ND 71-CRCW04021M00FKED C26083

Manufacturing & 3D CAD Deliverables

  • Complete 3D Populated Watch Assembly (STEP): Colby_Azumo_Smartwatch_Full_Assembly.step (contains all 71 3D bodies including the 4-tab stepped PCB, Azumo 11049-06 display CAD, flex cables, 302025 LiPo battery, TDK wireless coil, vibration motor, tap sensor, FPC connectors, and all SMDs for physical clearance verification in Fusion 360).
  • Interactive 3D Assembly Model (GLB): Colby_Azumo_Smartwatch_Full_Assembly.glb (authored with toggleable adomLayer groups and component hover tooltips).
  • PCBWay Turnkey Manufacturing Archive (ZIP): Colby_Azumo_Smartwatch_PCBWay.zip (contains all Gerber layers GTL, GBL, GTS, GBS, GTO, GBO, GTP, GBP, GKO, Excellon drill XLN, Pick-and-Place centroids ColbyAzumoSmartwatch-cpl.csv, BOM ColbyAzumoSmartwatch-bom.csv, and PCBWay_Fabrication_Notes.txt specifying Matte Black solder mask and Black silkscreen).
  • Project Engineering Datasheet (PDF): docs/colby-smartwatch-datasheet.pdf (embedded below).
  • AI Flow Run Report & Live Clips: AI Flow Run Report and Live Action Clips.