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Measure environmental data throughout the car, including relative humidity, airflow, and temperature (see data acquisition Data Acquisition SRR for more rationale)

Physical Design

• Each node consists of a main environment board + sensor breakout board

• Main environment board - interfaces with PSOM to provide ADC, I2C, and CAN functionality; connects to breakout board via short (TODO: absolute wire size/constraints after testing) wire

• Sensor breakout board - implements exposed humidity, airflow, and temperature sensors with all passive components and connectors a connector to interface with the main environment board

• Modularity - can pick and choose which sensors to use on each breakout board during assembly

  • Doesn’t require Not all sensors need to be present at every node

Rationale

• Sensor The sensor breakout board needs to be as small as possible to not disrupt airflow in the intake, exhaust, battery box, etc. (according to Cooling/Emech)

• Main The main board has to be at least the size of PSOM + any connector footprints, which is too large to place in the cooling system

  • Decided to break out sensors onto a separate board to balance airflow and data integrity

• Airflow sensor needs an uninterrupted flow of air to measure accurately - no other components can be placed in the line of measurement

• Humidity/Temperature sensors must also be exposed to the environment that’s being monitored

Interface

• Main environment boardwill send all environment

  • Sends environmental data to the

  main Environment Leaderboard

  • Data Acquisition leader board via internal

  Data Acq.

  • EnvironmentCAN

  • Will then be sent over TelemetryCAN to the telemetry module??

  • TODO:

  breakout system

  • TVS for i2c, fuse, connectors

  • pinouts for connectors on board silkscreen if also using for logic analzer debug points

  • possibly need i2c repeater: Need clarification on this

• Sensor breakout board

  • Receives sensor power and ground from the main board

    • All power connections are fused on the main board using PTC (resettable) fuses for overcurrent protection

  • Sends/receives I2C and Analog signals to/from the main board

    • Each I2C line on the main board is protected from ESD (transient voltage spikes) using TVS diodes

• I2C Repeater - https://www.nxp.com/products/interfaces/ic-spi-i3c-interface-devices/ic-bus-repeaters-hubs-extenders/level-translating-ic-bus-smbus-repeater:PCA9509

  • May be needed to reduce noise on I2C signal lines due to a large distance between the main board and the breakout

Context

Location of the board: Several boards will be located throughout the car as outlined below

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