ESP32-S3 Watch Design
arrange the schematic by functional group.
Thought for 9 sec
I’ll reorganize the schematic into clearly separated functional blocks, preserve every connection and value, then re-run electrical and geometry checks.
Worked for 13 mins 15 sec
Arranged all 52 schematic components into distinct functional groups: USB/protection, LiPo charging, buck-boost supply, ESP32-S3, I²C peripherals, OLED, and user controls. Connectivity is unchanged, with zero ERC errors, wire collisions, symbol collisions, or label collisions.
Open items
- 15 cosmetic lint warnings remain: three unavoidable pin-alignment kinks, two cross-group resistor-bank warnings, and duplicated distant-ground warnings for the isolated USB block.
Suggested next steps
- Define watch PCB dimensions and display/battery geometry.
- Start four-layer PCB placement with the ESP32 antenna keepout.
- Review placement before routing.
Layout, review and BOM
Start PCB layout
Define placement intent
Review schematic deeply
Check BOM risk
Fix cosmetic warnings
Refine this doc
Ask about this doc
Firmware Getting Started — ESP32-S3 OLED Watch
Toolchain
- ESP-IDF 5.x recommended; Arduino-ESP32 is also compatible.
- Target module: ESP32-S3-MINI-1-N8 (8 MB flash).
- Use native USB Serial/JTAG/OTG on GPIO19/GPIO20.
Pin Map
Table
| ESP32-S3 pin | Function | Net / device |
|---|---|---|
| GPIO19 | USB D- | USB_D_N through ESD and 0Ω link |
| GPIO20 | USB D+ | USB_D_P through ESD and 0Ω link |
| GPIO8 | I2C SCL | OLED, BMI270, MAX17048 |
| GPIO9 | I2C SDA | OLED, BMI270, MAX17048 |
| GPIO7 | IMU interrupt | BMI270 INT1 |
| GPIO10 | Fuel alert | MAX17048 active-low ALERT |
| GPIO11 | Charge status | BQ24074 active-low CHG |
| GPIO4 | User button 1 | Active low |
| GPIO5 | User button 2 | Active low |
| GPIO6 | User button 3 | Active low |
| GPIO0 | BOOT | Active-low boot button; external 10k pull-up |
| EN | RESET | Active-low reset button; 10k/1uF RC |
GPIO35–42 and GPIO45/46 are intentionally unused. GPIO12 is unused because the selected four-wire OLED module does not expose reset.
I2C Devices
- BMI270: 7-bit address 0x68 (SDO tied low).
- MAX17048: 7-bit address 0x36 (datasheet displays write/read bytes 0x6C/0x6D).
- SSD1306 module: commonly 0x3C; scan and confirm the fitted module before initialization.
- Bus speed: start at 400 kHz. One 4.7k pull-up pair is fitted near the MCU.
Initialization Order
- Configure button inputs with pull-ups and wake sources.
- Initialize I2C on GPIO8/GPIO9.
- Probe OLED, BMI270, and MAX17048 addresses.
- Load the Bosch BMI270 configuration blob; configure INT1 for desired active polarity and motion/tap wake.
- Configure MAX17048 alert thresholds and clear pending alert flags.
- Initialize SSD1306 and keep the display off until needed.
- Read charger status on GPIO11.
Native USB
- Hold BOOT low while toggling RESET to force ROM download mode if automatic USB download is unavailable.
- Select USB CDC/JTAG support in ESP-IDF menuconfig or the corresponding Arduino USB mode.
Low-Power Notes
- Turn off OLED pixels before sleep.
- Configure BMI270 low-power motion interrupt as a wake source.
- Use MAX17048 alert for low-battery wake/notification.
- Keep GPIO45/46 untouched during reset because they are strapping pins.
Toolchain
Pin Map
I2C Devices
Initialization Order
Native USB
Low-Power Notes
