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changes.mady.by.user Lakshay Gupta

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changes.mady.by.user Lakshay Gupta

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https://github.com/lhr-solar/BPS-LeaderDaughterBoard

Dimensions:


Goals:

  • This PCB will act as the main control unit for BPS
  • It will interface with the LeaderSOM PCB
  • Control Fans and Contactors

Old vs New Design:

2022-2024 BPS Leader2024 - 2026 BPS Leader
Only supports
  • Supports 2 wire fans
  • Supports 1 Contactor + Sense pins
  • IsoSPI interface to communicate with peripherals
  • Supports 2, 3, and 4 wire fans via I2C
  • Supports 3 Contactor + Sense pins
  • CAN Interface to communicate with peripherals
  • Receives input from the Ignition Switch

Requirements:

  • Interface with three Contactors
  • Add connectors for the LeaderSOM
  • Control a fault light
  • Control multiwire fans
  • Can interface with the Orion to control the fans

Schematic:

  • Contactors:
    • The circuit for each Contactor is the same
    • Image Added
    • Contactor_EN is a GPIO signal that controls a driver to turn on the Contactor
    • Contactor_Sense is a signal that indicates the state of the Contactor
    • D2 is a multi-diode package that acts as voltage clipping for the MCU. This will prevent signals above 3.3V from entering the MCU
  • Fan Control:
    • Orion Interface:
  • Ignition:
    • The Ignition switch uses 12V logic levels, so if we tried to put the 12V signals into our 3.3V logic MCU it would destroy the MCU
    • Image Added
  • Strobe Light:
    • As per regulations, we must have an external light to indicate to the outside that a BPS fault has occurred
    • FAULT is a GPIO signal (3.3V) from the MCU that controls a driver for the 12V light
    • D1 indicates whether or not the driver is on
    • Image Added

PCB:

  • The board is the same width as the LeaderSOM since connectors on all the sides of the LeaderSOM, and for size standardization we chose to only extend in one direction 
    • Image Added
  • All 12V nets were turned into pours
    • Contactors draw a lot of current at startup
  • Special care must be made to ensure that the right of the board is accessible since there is an SD card and Micro-USB cable  
    • Image Added
  • The bottom of the LeaderSOM has a 12V connector and both CarCAN connectors
  • The left of the LeaderSOM has the internal CAN connectors

Improvements:

  • Power Systems will add a fourth Contactor for BPS to control so a fourth Contactor circuit will need to be added
  • Add fault LEDs to the board at the bottom
  • Board layout was made in imperial (not standard) and multiple things are unaligned