Project Specification — Wearable Industrial Safety Monitor
Requirements
- 2-layer PCB, approximately 70 mm x 50 mm, rounded corners.
- Bottom layer used primarily as a continuous GND plane.
- Compact wearable industrial safety monitor.
- MCU: STM32C011 microcontroller/module.
- WiFi: ESP8266 module connected over UART.
- Sensors: MPU6050 over I2C, BME280 over I2C, MAX4466 microphone analog output to MCU ADC.
- Outputs: RGB LED with current-limiting resistors; vibration motor driven by 2N2222 NPN transistor and flyback diode.
- Inputs: SOS pushbutton and reset pushbutton.
- Power: single-cell LiPo input through JST connector, AP7361 3.3 V regulator, regulator input/output capacitors, IC decoupling capacitors.
- I2C pull-ups: 4.7 kΩ to 3.3 V on SDA and SCL.
- Layout: separate analog microphone area from digital/RF area, keep ESP8266 antenna clearance free, manufacturable routing.
Initial Architecture
VBAT from JST connector feeds AP7361-33 LDO. 3V3 powers STM32C011, ESP8266 module, MPU6050, BME280, MAX4466, and RGB LED channels. STM32C011 is the central controller; ESP8266 is a UART WiFi coprocessor. MPU6050 and BME280 share the I2C bus with one pull-up pair. MAX4466 analog output is routed to an STM32 ADC-capable pin. RGB LED channels and vibration motor driver are controlled by GPIO/PWM-capable outputs.
Assumptions
- ESP8266 peak current requires a regulator/power path capable of at least 500 mA with adequate bulk capacitance; AP7361 variant should be selected/rated accordingly.
- The ESP8266 module will be placed at a board edge with its PCB antenna facing outward and with copper/component keepout under/in front of the antenna.
- STM32C011 pin assignment will use common GPIO names and be verified against the selected package/module pinout before manufacturing.