Due Dates:

• Requirements/Considerations - 4/7/2025

• Component Selection - 4/26/2025

• Initial Schematic - 7/2/2025

• Initial Layout - 7/10/2025

• Rev. A Ordered - 8/25/2025

• Firmware/Testing - 10/1/2025

  • breadboard sensors to verify correct resistances etc

Description/Purpose

Controls speed of water cooling pump and two fans. Additionally, interprets data from temperature sensors and flowrate sensor to send over CarCAN.

Requirements

• Pump (1x)

  • https://www.rigidhvac.com/store/products/12v-24v-pump-reservoir-combo-65mm

  • Receive FG signal and send PWM signal to/from pump

  • Requires +24V input (9.5W)

  • Selected because there’s basically no 24V PC pumps

• Fan (2x)

  • https://www.mouser.com/ProductDetail/Orion-Fans/OD1225-24HBXE10A?qs=Jm2GQyTW%2Fbi2e5YFByfBgA%3D%3D

  • 4 pin fans (+24V, TACH, PWM, GND)

  • Send PWM signal from fan control IC to NMOS based on TACH output

  • Selected w/ PTN for 24V + air volume

• Temperature sensors (2x)

  • https://koolance.com/sen-ap008b-coolant-temperature-sensor-brass-10k-ohm

  • 10k thermistor, use ADC to convert

  • Placed on the radiator

• Flow rate sensor (1x)

  • https://www.vegetronix.com/Products/Flow-Sensors/VG-FLOW-0_5/

  • 3 pin (+12V, GND, Flow_Out)

  • Flow_Out drives PMOS to get 3.3V frequency to psom

  • BSP fittings for less fluid leakage

  • Selected because decent documentation and versatile Vin

• Mechanical

  • Packaging

    • Enclosure contains pump board + pump

    • Coordinate with Nitish on ptn

  • All Connections (includes internal to enclosure)

    • **Recrimp all electronics to be fitted with MX150s

    • CarCANIn (1x2)

    • CarCANOut (1x2)

    • Flowrate (1x3)

    • Pump (1x4)

    • Temp1 (1x2)

    • Temp2 (1x2)

    • Temp3 (1x2)

    • Fan1 (1x3)

    • Fan2 (1x3)

    • LVPower (1x2)

    • 3.3VIn (1x2) - only for revA + internal to enclosure

    • 5VIn (1x2) - only for revA + internal to enclosure

    • PSOM - internal to enclosure

Application Note

how does this board integrate with others + any harnessing/bringup considerations. anyone should be able to read this and integrate this board into the electrical system

Context

Location of the board: Back left near radiator + battery

External Connection List

Main

Rev A Schematics + Layout + 3D model

Rev A Screenshots

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Rev B Schematics + Layout + 3D model

Rev B Screenshots

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Circuit Components

all uniques (non-passives) in BOM + rationale for selection

• Fan control IC (1x)

  • https://ww1.microchip.com/downloads/aemDocuments/documents/MSLD/ProductDocuments/DataSheets/EMC2301-2-3-5-Data-Sheet-DS20006532A.pdf

  • Communicates with psom over I2C

  • Selected to remain consistent with BPS leader fan control

• PSOM pins used:

  • Fans

    • FAN_SCL - PB6

    • FAN_SDA - PB7

    • SMBALERT - PB12

  • Temp Sensors

    • TEMP1 - PA4 (ADC)

    • TEMP2 - PA5 (ADC)

  • Flowrate Sensors

    • FLOW1 - PB3

    • FLOW2 - PA2 (not used on car)

  • Pump

    • TACH_PSOM - PA11

    • PWM_PSOM - PB15

  • Debug LEDs

    • Pump - PA0

    • Fan - PA6

    • Fan Chip - PB14

    • Temp - PA12

    • Status - PB0

Firmware

Drivers

High-Level (Block Diagram)

Rev B Testing Plan

• ✅ Phase 0: Blinky + LED testing

  • ✅ Test LED driver to make sure LED turns on when directed

  • ✅ Baseline to help with future debugging

• ✅ Phase 1: Temp testing

  • ✅ Write temp driver - include non blocking print statements

  • ✅ Vary thermistor temp with heat gun/breathing on it

• ✅ Phase 2: Fan testing

  • ✅ Verify hardware is correct by testing fan with waveform generator + logic analyzer

  • ✅ Firmware mostly done by Ravi already, just need to call fan chip driver correctly

• ✅ Phase 3: Pump testing

  • ✅ Start by trying to use the fan chip to control speed

  • If that doesn’t work, switch to psom

    • it worked! might write a psom driver eventually tho jic

• ✅ Phase 4: Flowrate testing

  • ✅ Test flowrate circuitry with waveform generator + logic analyzer

  • ✅ Once hardware is working, add firmware

    • adapter is the wrong size… will talk to ptn at workday to figure out next steps

      • still working on getting a new one… will write driver and test with air instead

      • new adapter secured, but it leaks hehe

  • ✅ Verify accuracy by comparing output to (pump max flowrate)*(pwm duty cycle)

• Phase 5: CAN

  • ✅ Loopback mode using embedded sharepoint test

  • ✅ Loopback mode using actual CAN IDs

  • Send CAN messages

    • ✅ Temp - still need to change dbc to be 32b per temp (milicelsius)

    • Flowrate

    • Fans

  • Receive CAN messages

    • BPSL temp

    • Car speed (?)

• Phase 5: Control loop

  • Once drivers + hardware is verified, work with ptn to tune control algorithm

  • Figure out what’s the optimal temp to maintain + fault threshold

    • Temp threshold = 45˚C

    • Needs empirical testing but cooling will likely also depend on car speed