InkTime-TSC Project
This project presents the design and development of a low-power, multi-functional smartwatch platform. The system is built around the nRF52840 SoC and integrates an E-paper display, motion sensing capabilities, and optimized power management within a compact PCB tailored for wearable devices.
| Cant. | Referințe | Valoare | Capsulă | Descriere | MPN |
|---|---|---|---|---|---|
| 1 | ANT1 | 2450AT18B100E | ANTC3216 | Antennas 2.45GHz | 2450AT18B100E |
| 4 | C1, C2, C17, C18 | 12pF | 0201 | Generic chip capacitor | - |
| 6 | C29, C30, C31, C32, C37, C38 | 1uF | 0201 | Generic chip capacitor | - |
| 1 | IC1 | BQ25180YBGR | 8-DSBGA | Charger IC Li-Ion | Texas Instruments |
| 1 | IC2 | DRV2605YZFR | 9-DSBGA | Haptic Driver | DRV2605YZFR |
| 1 | IC9 | RT6160AWSC | 15-WLCSP | Buck-Boost Regulator | RT6160AWSC |
| 1 | U1 | NRF52840_QF | AQFN-73 | nRF52840 SoC | - |
| 14 | TP1...TP_VREG | Test Point | TP20R | Test pads | - |
Hardware Overview
- Core Processing Unit: nRF52840
The nRF52840 System-on-Chip serves as the central controller, chosen for its strong balance between computational performance and low energy consumption.
Main Characteristics:
ARM Cortex-M4F core with floating-point support Native USB functionality Flexible GPIO configuration supporting SPI and I2C interfaces
Clocking:
32 MHz external crystal for high-speed operation 32.768 kHz crystal for accurate timekeeping during low-power modes
Wireless Capability:
Integrated 2.4 GHz RF frontend paired with a ceramic antenna for Bluetooth Low Energy (BLE) communication 2. Power Management and Charging
The device includes a carefully designed power architecture to support portable operation.
USB-C Port:
Provides 5V input and data connectivity Protected against electrostatic discharge using the USBLC6-2SC6Y
Battery Charging and Regulation:
BQ25180 handles LiPo charging and power path management RT6160 DC/DC converter ensures efficient voltage regulation
Filtering and Stability:
LC filtering network reduces noise and stabilizes supply rails
Battery Monitoring:
MAX17048 fuel gauge communicates via I2C to estimate battery charge level accurately 3. E-Paper Display Module
A 1.54-inch E-paper display is used as the main visual interface, connected through a 24-pin FPC connector.
Driving Mechanism:
A custom boost circuit (using MOSFETs, Schottky diodes, and capacitors) generates the required high voltages
Communication:
SPI interface with dedicated control signals: DC (Data/Command), RST (Reset), and BUSY
Design Motivation:
The display retains the image without continuous power, making it ideal for always-on wearable applications 4. Motion Sensing and Haptic Feedback
IMU Sensor:
BMA421 accelerometer used for motion tracking I2C communication interface Interrupt pins (INT1, INT2) allow the MCU to wake on movement or gesture detection
Haptic System:
DRV2605 driver controls vibration feedback Offloads waveform generation from the MCU for efficient operation 5. User Interface and Debugging
Buttons:
Three physical buttons (Up, Enter, Down) connected to GPIOs for navigation