[WIP]PeripheralSOM PCB

GitHub:

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

Dimensions:

40 x 50 mm

Goals:

• A generic board that will take inputs from various sensors and chips, and transfer that data onto a CAN bus
• Intersection of all our MCU board's components
• Remove the need for redesigning complicated MCU, CAN, and buck converter circuits
• Low power

Requirements:

• Use a low-power MCU (STM32L4)
• Able to be daisy-chained via a 5V and CAN line
• Can be powered and power other boards
• Small

Schematic:

https://github.com/lhr-solar/BPS-PeripheralSOMPCB/blob/bom/BPS-PeripheralSOM_SCH.pdf

Power Distribution:

• 
• Takes 5V from an outside source → Isolates it → LDO down to 3.3V
• The left section is voltage protection:
  • The TVS diode prevents voltage spikes
  • The MOSFET is for reverse polarity protection
• These boards will be in very noisy situations, so we isolate the GNDs between the boards

USB:

CAN:

MCU:

• Bypass capacitors
• GND and GNDA filter
• Terminating resistors

SW Pullups:

SPI Protection:

PCB:

https://github.com/lhr-solar/BPS-PeripheralSOMPCB/blob/bom/BPS-PeripheralSOM_PCB.png

MCU:

Improvements:

• 3.3V test points for standalone testing with a 3.3V source