References

The design concerns referenced here are mainly paraphrased/pulled from these sources:

• 2024 - 2026 Electrical PDR Presentations

Please reference these for the actual comments made on PDR.

Blindspot Sensor

• As far as driver safety is concerned, two side cameras may make more sense than blindspot sensors (or perhaps a combination of both!)
• If planning to still do blindspot sensors, do not consider cost a factor at all (since this is a pretty safety critical element)
• Testing will need to be done in different light conditions + glare –  be careful about infrared
• Perhaps even upgrading the backup camera will help with this

Lights

• Make sure that light power isn't supplied by the peripheral boards –  they're only capable of 1W maximum and are mainly meant for sensors
  • As long as the power itself comes from an external source (e.g. supplemental battery) and is only driven by the peripheral boards, it would be fine

Power Draw

• I'd like to try to limit power draw as much as possible on this new design, and our previous power draw (measured 2/17/24) was ~18.5W
  • If we can stay in this range or maybe even get lower than this, it would be good. 1W is provided as an upper bound on each SOM, but with smart firmware we can lower this further
  • This may be tough especially considering blindspot sensors, new display, and possibly even side cameras.

Motor Consideration

• Investigate https://www.h3x.tech/#hpdm-30 as a possible motor/MC alternative since we have a partnership with them
  • No, too much power

Steering Wheel Buttons

• Nathan Lee 100% does not like the idea of using the quick disconnect again due to integration issues, so we may have to come up with something else
• Consider a peripheral board on the steering wheel to interface with the buttons, that just spits shit out over CAN to leader. This makes # of wires to steering wheel go from like 8 to like 4
• Button placement and steering wheel design needs to be ironed out with ergo as soon as possible (i.e. whenever ergo is done with current gen stuff)
  • Horn button needs to be considered & integrated
  • chase car radio button placement needs to be considered (communicate with dataacq). this should be a completely independent circuit since it's just a button that clips onto the steering wheel and plugs into the walkie talkie

Display

• Define display requirements such as:
  • Minimum brightness
  • Viewing angle
  • Glare
• Our definite requirements for right now are probably:
  • 7 inch
  • Not much more power draw than the Nextion (which was 1.25W) 
• The Waveshare + RPI display was ~3.1W total and the Riverdi display was ~4.05W iirc
• A lot of displays exist that could be less power draw in that they have their own internal control unit
  • Instead of leader → RPI → display, it could be leader → display where the display does all the control of pixels and stuff on its own (think Nextion)
  • Another bit of reasoning for this is that the RPI runs full linux, whereas we only need an embedded RTOS really if we're just using it as an interface for the display (full linux is unnecessary)
• See https://www.buydisplay.com/
• Options (communication via SPI):
  
  • 500 nits, 3.15W: https://www.buydisplay.com/spi-1280x400-7-84-inch-ips-tft-lcd-module-optl-capacitive-touch
  • 600 nits, 3W: https://www.buydisplay.com/7-inch-1024x600-ips-tft-touch-display-module-with-i2c-spi-for-arduino

Horn

• Find horn that's low power draw THAT MEETS REGULATION REQUIREMENTS
  • The regs requirements are our main constraining factor on limiting power draw of this. We need a certain volume level of sound iirc
  • Lakshay's horn: https://www.amazon.com/SoundOriginal-Universal-Motorcycle-Electric-Waterproof/dp/B072QBNTSM

Backup Camera

• Verify our current backup camera is viable
  
  • The regs require a way for the driver to always view behind the car. We accomplish this with a backup camera, so this is critical requirement.
  • Tested on 3/2/2024 and it does work but the display is not good at all viewing angles. Need to check with ergo on how this might look in reality.

Data Acq Optimal Speed

• Originally, data acquisition was going to send us an optimal speed to go at a regular interval. Controls was going to add this information to the display for the driver to use.
• Idea is no longer feasible due to data acq processing their information on the cloud and not on a board in the car.

Array Precharge

• Array does need precharge!
• Mostly a power systems problem

Peripheral Board Voltage Drop

See 2024 Controls Post-PDR Review: Peripheral Board CAN Voltage Drop.

Design Decisions

1. Using side cameras instead of blind spot sensors - Aiden again! (Thank u)
   1. Auxiliary Display
      1. Decided on separate display that will switch inputs when blinkers are pressed
      2. Peripheral Board required - same peripheral SOM, different daughter, DISPLAY DAUGHTER
   2. Communication protocol – interfacing with HW
      1. Are we able to display the video?
   3. Third display for side cameras 
      1. Power draw concerns
      2. Integration of side camera into main display requires less power draw
   4. More research on camera
      1. Noise tolerant video! 
2. Main Display
   1. 500 nits, 3.15W: https://www.buydisplay.com/spi-1280x400-7-84-inch-ips-tft-lcd-module-optl-capacitive-touch - long boi display
   2. Will also show backup camera on one side permanently - same camera as side cameras (3 of the same)
   3. Peripheral Board required
3. Steering Wheel
   1. Peripheral Board required
   2. Takes all the buttons in and outputs onto CAN
4. Peripheral Boards
   1. 4 Peripheral SOMS
      1. 2x normal peripheral daughter - steering wheel & lights
      2. 2x display daughters - one for each display
5. Horn
   1. https://www.amazon.com/SoundOriginal-Universal-Motorcycle-Electric-Waterproof/dp/B072QBNTSM
6. Electronic brake and regen still needs to be revisited
   1. Requires significant testing with functional car!!
   2. Would regen/blended braking all the time be beneficial?
7. CAN Topology
   1. Option 1
8. Pedal hardware issue detection
   1. Sense pins
   2. Use Pull Down Resistor