Hardware Requirements

Table of Contents

All Requirements

• 2024 Regs (need to comply with 2026, which are not released) https://www.americansolarchallenge.org/ASC/wp-content/uploads/2023/11/ASC2024-Regs-EXTERNAL-RELEASE-C.pdf

Leader Board

• MCU

• 2x CAN chips and in/out connector pairs

  • Controls CAN

  • Car CAN

• Receive main power/ground

• Receive isolated power/ground

• Supply 1x power/ground for peripheral SOM

Peripheral Board - Pedals

1x: Front-ish middle

• Step down & supply power to (3.3V?)

  • Accelerator pedal

  • Brake pedal

• Read position of accelerator pedal (potentiometer)

• Read if brake pedal is pressed (potentiometer/brake line)

• Sense if pedals are disconnected

Peripheral Board - Lights

5x: Front, Side left, Side right, Back, Canopy

• Supply power to 4x lights

• Interface with 1x blindspot camera

• Send camera output to display [board] (alternative: direct routing from camera to display)

• [Backup GPIO for 2x lights?]

• MOSFETs

Canopy psom

• Current design:

  • Open

    

     

Design Option—cameras

Powering the cameras using a peripheral board vs pi ethernet

• Using Power Over Ethernet (POE)

  • if we use an ethernet connection, we wouldn’t need to connect the cameras to peripheral board at all—would be directly connected to the dashboard (or display?) ethernet cable (pi is connected to wherever the ethernet cable is connected to)

  • would only need the psom to power central brakelight

• Using peripheral board

  • L4 chip (on peripheral board) does not have ethernet

    • if we connect the cameras to the pi, this is not a problem

  • ethernet kinda may not be super stable

  • just need to add power breakouts to lights board

Questions to answer:

• can our psom power the cameras?

• does the raspberry pi 0 connect to ethernet?

  • can attach a HAT to the pi or create an adapter

  • display will need either ethernet connection or some other protocol in order to display cam data

• If we use POE, would we need two lines between each camera and the pi to power the cameras and also send data to the pi the to the display?

  • flow of data: camera sensors → pi 0 → display

• Consider that we need a board for blindspot cameras

• Convert ethernet → pi and from pi → HDMI for display

Peripheral Board - Contactor Board

• does array need precharge - yes, but not our domain

• Need to send ignition message to BPS - software

Design Decisions

Combining Left/Right Lighting boards for the front and back lights

• Separate:

  • 4 wires between left and right psoms

    • CAN H/L

    • Power/ground

• Combined:

  • 4 wires going left/right from board

    • Turn signal

    • Head/tail lights

• Pros to combined:

  • One/two less boards

    • Less soldering

    • Less wiring: Eliminates CAN and power wiring between boards

    • Less boards to order and test

• Cons to combined:

  • Longer power wires

  • More complex board

    • Supply both sides

    • Logic to toggle left or right (maybe not that difficult)

• Justification

  • Overall wire length is similar (Four wires- only difference is CAN vs GPIO)

    • GPIO would likely by 12V and therefore will not suffer a large voltage drop while crossing the width of the car

  • Added capabilities aren’t complex

    • More GPIO,

Powering cameras

Current decision: leaning towards using ethernet to power cameras

Pros to ethernet:

• if we use an ethernet connection, we wouldn’t need to connect the cameras to peripheral board at all—would be directly connected to the dashboard (or display?) ethernet cable (pi is connected to wherever the ethernet cable is connected to)

• would only need the psom to power central brakelight

• can attach a HAT to the pi 0 or use usb to ethernet an adapter

• cable can both power camera and send data ( ? )

Cons to ethernet:

• More work to figure out how to do that (maybe not that hard? idk)

• ethernet stability concerns?

• new wiring requirements

• will need a network switch (can buy or make ourselves)

Relevant Regulations (FSGP/ASC 2024)

8.2.C Supplemental Batteries

8.2.C.1 Supplemental, replaceable batteries carried in the solar car may be used to power: Main Power Switch, driver ventilation fans (if solely used for driver ventilation), telemetry, and the horn. All other systems present on the car must be powered off the main battery.

8.2.C.3 During a battery fault in which the BPS has automatically opened the Main Power Switch, the supplemental battery must be used to power the BPS, BPS Strobe, and BPS Fault Driver Indication. While in such a fault state, the supplemental battery may be used to power any other systems (signal lights, rear view camera, telemetry, etc) that do not provide motive power to the vehicle.

8.6.A Main Power Switch

8.6.A.2 The solar car driver must have overriding control and the ability to turn the power switch off at all times.

8.6.A.3 The power switch control location must be within easy reach of the driver and clearly labeled with the words “POWER”, “ON” and “OFF”. All letters must be 10 mm tall or larger.

8.6.B BPS Fault Dash Indication

The driver is to have an illuminated dash indication of a BPS fault to provide warning of an automatic opening of the Main Power Switch.

8.8.A Sole Control

Any parameter that influences the safe and reliable operation of the vehicle must be under the sole control of the driver

8.8.B Accelerator

Accelerator mechanisms on solar cars must be free moving, and when released, must return to the zero position. Should a pedal accelerator be used, it shall be mounted such that it is operated by the right foot and it shall be located to the driver’s right of the brake pedal (if equipped).

8.8.C Cruise Control

If the solar car is equipped with cruise control, it can only be activated by the driver. The cruise control must be designed to automatically deactivate when the brake controls are manually actuated by the driver, or when the car is shut off.

8.8.D Reverse

The solar car must be able to be driven backwards under its own power with the driver seated in the normal position.

9.4 Lighting

All lights required in this regulation shall be at least as bright as the reference standard defined below from 30 m away throughout the required viewing angles as defined below. Inspection for the viewing angles and light intensity can be conducted at any point within the defined distance and view angles. All positions are to the center of the light emitting portion of the light.

9.4.A Daytime Running Lights

9.4.A.1 Position: shall be located at least 600 mm apart (at least 400 mm apart if the car is less than 1300 mm wide), at least 250 mm above the ground, and at a distance no further back than 200 mm from the absolute front of the vehicle.

9.4.A.2 Color: white

9.4.A.3 Viewing Angle: 10° upwards, 10° downwards, 20 ° outwards, and 20° inwards

9.4.A.4 Operation: The Daytime Running Lights shall operate whenever driving is possible (motor power is enabled). It is permissible to disable the running light while the co-located front turn indicator is in operation. The turn indicator has the priority in operation.

9.4.B Front Turn Indicators

9.4.B.1 Position: shall be located at least 600 mm apart (at least 400 mm apart if the car is less than 1300 mm wide), at least 350 mm above the ground, and at a distance no further back than 175 mm from the absolute front of the vehicle.

9.4.B.2 Shall flash between 60 and 120 pulses per minute

9.4.B.3 Color: amber

9.4.B.4 Viewing Angle: 80° from center in outwards, 45° from center in inwards (see Figure 1), 5° down, and 15° up from horizontal.

9.4.B.5 Operation: If the co-located Daytime Running Light is not disabled during turn indicator operation, the turn indicator shall be visible with the running light on.

9.4.C Side Marker Turn Indicators

9.4.C.1 Position: shall be mounted on each side of the vehicle between 500 and 1800 mm rearward from the absolute front of the vehicle and within 400 mm of the extreme outer edge of the car.

9.4.C.2 Shall flash between 60 and 120 pulses per minute

9.4.C.3 Color: amber 9.4.C.4 Viewing Angle: 5° down and 15° up from horizontal, horizontal visibility as shown in Figure 1:

Open

9.4.D Rear Brake Lights

9.4.D.1 Position: shall be located within 400 mm of the extreme outer edge of the car on each side, at least 600 mm apart (400 mm if the car is less than 1300 mm wide), at least 350 mm above the ground, and at a distance no further forward than 200 mm from the absolute rear of the vehicle.

9.4.D.2 It is permissible to have one set of lights per side of the car which operate as both the brake lights and turn indicators. The turn indicator operation has the priority in operation.

9.4.D.3 Color: red 9.4.D.4 Viewing Angle: 45° from center outwards and inwards, 5° down, and 15° up from horizontal.

9.4.D.5 Operation: Brake lights should operate if and only if the driver presses the brake pedal or regenerative braking is active.

9.4.E Rear Turn Indicators

9.4.E.1 Position: shall be located within 400 mm of the extreme outer edge of the car on each side, at least 600 mm apart (400 mm if the car is less than 1300 mm wide), at least 350 mm above the ground and at a distance no further forward than 200 mm from the absolute rear of the vehicle.

9.4.E.2 It is permissible to have one set of lights per side of the car which operate as both the brake lights and turn indicators. The turn indicator operation has the priority in operation.

9.4.E.3 Shall flash between 60 and 120 pulses per minute

9.4.E.4 Color: amber (if separately equipped from Rear Brake Lights)

9.4.E.5 Viewing Angle: 80° from center outwards, 45° from center inwards, 5° down, and 15° up from horizontal.

9.4.F High Mounted Center Brake Light

9.4.F.1 Position: Viewed from behind the solar car, the lateral position of the light shall coincide with the visual center of the solar car (see the examples in the following diagram). The top of the lamp shall be less than 150mm below the highest point of the car, and the bottom of the lamp shall be higher than the top of the rear brake lights.

9.4.F.2 Color: red

9.4.F.3 Viewing Angle: 10° from center in both left and right, and 10° up and 5° down from horizontal

9.4.H Emergency Hazard

The front turn indicators, side marker turn indicators, and rear turn indicators shall be able to be activated simultaneously and flash in sync as an Emergency Hazard signal.

9.5.E Rear Vision

9.5.E.1 All solar cars must be equipped with a rear-view system that at all times will allow the driver to see a vehicle 15 m directly behind the solar car and up to 30° off center. The system must provide the driver with a single reflex type image and must operate without driver input. The driver will be required to identify the direction of an arrow with a 200 mm thick brush stoke on a 1 m2 board held about 1 m off the ground.

9.5.E.2 If equipped: the camera and view screen shall be fixed in position such that road bumps and vehicle vibration will not alter the viewing angles.

9.5.E.3 If equipped: the view screen shall be positioned such that the driver shall be able to see the view screen while seated in normal driving position.

Questions

• Exterior e-stop

• Will the display and dashboard each be their own boards?

• Are long GPIO power wires okay?

  • 12V is okay across long distances, though 5V and 3.3V may suffer