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Design Notes
Modular Sensor System Architecture
  • Main controller: Arduino Nano ESP32
  • Shared bus: 3.3V I2C
  • Peripheral node representations: Modulino Buttons and Modulino Pixels modeled as I2C-addressable functional blocks
  • External connector: Qwiic JST-SH 4-pin daisy-chain interface
  • Additional sensor interface: dedicated 3-wire E3JK retro-reflective sensor input block
Bus Rules
  • Logic level: 3.3V only
  • Shared pull-ups: 4.7k on SDA and 4.7k on SCL to 3.3V
  • Qwiic pin order: GND, 3.3V, SDA, SCL
Addressing Plan
  • Keep each node on a unique I2C address
E3JK Sensor Power Architecture
  • The E3JK retro-reflective laser sensor is treated as a strict 12V field device in this project.
  • The sensor power domain is separate from the Arduino and Qwiic logic domain.
  • J2 is the field wiring connector for the E3JK block.
  • J2 pin mapping: Pin_1 = +12V sensor supply, Pin_2 = GND, Pin_3 = sensor output.
  • Net 12V_SENSOR powers only the E3JK connector supply pin and its local bypass capacitor.
  • Net 3V3 powers only the Arduino Nano ESP32, the I2C bus pull-ups, and the Qwiic/Modulino logic domain.
  • Grounds are shared so the sensor output has a defined reference to the MCU input stage.
E3JK Sensor Signal Conditioning
  • The E3JK output is not routed directly into the MCU.
  • The raw field output net is E3JK_OUT_12V.
  • R3 is the top resistor of the divider from E3JK_OUT_12V to the MCU-facing node.
  • R4 is the bottom resistor of the divider from the MCU-facing node to GND.
  • Divider values: R3 = 27kΩ and R4 = 10kΩ.
  • Expected MCU input voltage at 12V sensor output:
    • Vout = 12V x 10k / (27k + 10k)
    • Vout = 3.243V
  • The conditioned net is E3JK_OUT_3V3 and it connects to Arduino Nano ESP32 pin D2.
  • This divider keeps the MCU input within the 3.3V logic domain while preserving a direct digital indication from the sensor.
Local Decoupling
  • C1 is a 100nF bypass capacitor from 12V_SENSOR to GND at the sensor connector.
  • This capacitor is local to the field connector and supports the dedicated 12V sensor domain.
Integration Notes
  • The existing I2C Modulino architecture remains unchanged on SDA and SCL.
  • The E3JK interface is isolated functionally from the I2C bus and only adds one GPIO input on the controller.
  • No Qwiic or Modulino signals are exposed to the 12V sensor domain.
Notes
  • The Modulino nodes are represented by functionally equivalent I2C devices available in the library so the bus architecture, addressing, and connector scheme can be captured in the schematic.

    Modular Sensor System Architecture

    Bus Rules

    Addressing Plan

    E3JK Sensor Power Architecture

    E3JK Sensor Signal Conditioning

    Local Decoupling

    Integration Notes

    Notes

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    Design Notes

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Arduino Nano ESP32 Modulino Hub

Arduino Nano ESP32 Modulino Hub thumbnail
Modular 3.3V Arduino Nano ESP32 controller with I2C-connected Modulino Buttons and LED Pixels nodes plus Qwiic JST-SH daisy-chain connector.

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