NODE IO BOARD

NODE IO BOARD

The NODE IO BOARD is an embedded hardware node featuring an ESP32-C3 microcontroller, onboard environmental and motion sensors, USB-C power/data delivery, and external micro-SD card storage. It serves as a compact, all-in-one sensor node designed for IoT applications, environmental monitoring, and motion tracking.

Technical Specifications

1. Main Controller

• MCU: ESP32-C3-MINI-1 / ESP32-C3-MINI-2 module (RISC-V single-core processor).

• Auto-Flash/Reset Circuitry: Dual NPN transistor circuit (DTR/RTS) for automatic bootloader entry and flashing over USB.

• Tactile Switches: Dedicated RESET and BOOT push buttons.

2. Power Supply

• Power Input: USB Type-C Receptacle (USB 2.0 interface) or external 5V input header (J2).

• ESD Protection: Dedicated ESD protection diodes (ESD9B5.0ST5G) across VBUS, D+, and D- lines.

• Voltage Regulation: Onboard LD1117S33TR LDO regulator stepping down 5V (VBUS) to 3.3V for MCU and sensor power rails.

3. USB to UART Bridge

• Bridge IC: CP2102N (QFN-28) USB-to-UART bridge controller.

• Communicates directly with the ESP32-C3 via U0RXD and U0TXD pins.

4. Onboard Sensors & Peripherals

• Environmental Sensor: BME688 gas, temperature, pressure, and humidity sensor connected over I²C (SCL, SDA).

• Inertial Measurement Unit (IMU): BMI323 6-axis IMU connected via I²C (SCL, SDA) with dedicated interrupt lines (BMI_INT1, BMI_INT2).

• MicroSD Card Slot: SPI-driven SD card slot (MEM2067) connected via SPI lines (SPI_CLK, MOSI, MISO, SPI_CS) for local data logging.

Block Diagram Overview

               +-----------------------+
               |  USB-C / 5V Header    |
               +-----------+-----------+
                           |
            +--------------+--------------+
            |                             |
    +-------v-------+             +-------v-------+
    | 3.3V LDO      |             | CP2102N USB-  |
    | (LD1117S33)   |             | to-UART Bridge|
    +-------+-------+             +-------+-------+
            |                             |
            +--------------+--------------+
                           |
                 +---------v---------+
                 |    ESP32-C3       |
                 |  Microcontroller  |
                 +----+----+----+----+
                      |    |    |
       +--------------+    |    +---------------+
       | I2C               | SPI                | Interrupts / Controls
+------v-------+    +------v-------+    +-------v------+
|   BME688     |    |  MicroSD     |    | Boot & Reset |
| Env Sensor   |    | Card Slot    |    |   Buttons    |
+--------------+    +--------------+    +--------------+

Project Design Files

This hardware project was designed in KiCad 10.0:

• NODE IO BOARD.kicad_sch — Schematic source file

• Hardware revision: Rev 1.0