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2.6 Pressure Sensor PCB

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John-Paul Chouery edited this page Aug 28, 2024 · 2 revisions

Overview

This project focuses on designing a PCB for the MS583730BA01-50 pressure sensor, which is used in the AUV to determine the depth. The sensor captures pressure, temperature, depth, and altitude, but we primarily use it for depth measurement.

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Choosing Components

Pressure Sensor: MS583730BA01-50

  • Pinout:

    • Power: Connect to the 3.3V output of an LDO.
    • Ground: Connect to the ground plane.
    • SCL (I2C Slave Clock): Connect directly to the MCU’s dedicated I2C pin.
    • SDA (I2C Slave Data): Connect directly to the MCU’s dedicated I2C pin.

  • Connection to MCU:

    • The pressure sensor connects to an MCU on a separate board that powers and communicates with this PCB.
    • Connector: Use a 4-pin Molex Micro-Fit connector (part number: 43045-0427) for Power, Ground, SCL, and SDA connections.

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Power Regulation: LDO (Low Dropout Regulator)

  • Problem: The pressure sensor requires a 3.3V power input, but the input voltage to the PCB is 5V.
  • Solution: Use an LDO (Low Dropout Regulator) to step down the voltage.
  • LDO Choice: TPS78001DDCT
    • Function: Converts 5V input to 3.3V output (3V3).
    • Reference Circuit: Refer to the LDO's datasheet for the reference circuit to connect passive components.

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Note: The internal reference voltage (VFB) of the LDO is 1.1216V typical. Use this value to calculate the resistors required for your circuit.

I2C Pull-up Resistors

  • Resistors for I2C: The I2C communication lines (SCL and SDA) require pull-up resistors to function correctly.
    • Value: Typically, 4.7kΩ or 10kΩ resistors are used for I2C pull-up.
    • Placement: Place one resistor between SCL and 3.3V, and another between SDA and 3.3V.

Datasheets

Importance of Reading Datasheets:

  • Always refer to the datasheets to understand the specifications, pinouts, and recommended circuits for components.
  • Datasheets provide essential details, such as maximum ratings, operating conditions, and application notes, which are crucial for designing reliable circuits.

Starting the Project

Project Setup in Altium Designer

  • A sample PCB layout is available in the Altium workspace. Access it to guide your design.
  • File Naming: Save your PCB design in the Altium workspace of McGill Robotics in the AUV folder. Use the naming format: AUV_Tutorial_Pressure_Sensor_PCB_[Your Initials].

Design Instructions

  • Schematic Design: Begin by placing the MS5837 pressure sensor, LDO, I2C pull-up resistors, and all necessary passive components.
  • Routing:
    • Follow best practices for trace routing and component placement.
    • Ensure that the 3.3V and 5V power lines are properly routed and decoupled with capacitors.

Submission Instructions

  • Check Components: Double-check all component placements, labels, and connections.
  • Submission: Once the PCB design is complete, submit it as per the file naming guidelines mentioned above.

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