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