#638 – Building AR Headsets with Aedan Cullen

Welcome, Aedan Cullen!

• Chris first learned of Aedan from his 2022 Hackaday talk about building an AR system
• AR is “Augmented Reality”, but that term is different depending on the company / headset (think “magic leap” vs “google glass”)
• Got into AR because of robotics, he had be doing software around SLAM and CV
• Interacting with objects in 3D space
• The first board he was working with was the Jetson TK1
• Magic Leap’s “Lightpack” had a Tegra in it
• Apple’s new Vision Pro is more like VR with passthrough (and creepy eyes!)
• Being able to wear an AR unit all day
• Resolution matters
• What is it worth spending power on in a headset?
• The previous rev used the AllWinner D1 RISCV and can support one camera
• Which way should you point a camera on a pair of glasses?
• MIPI DSI outputs and DSP processing
• Lots of SIPs available for high density designs
• Octavo makes SIPs out of other companies’ silicon.
• Jason and Robert from BeagleBoard talked about Octavo when they were on the show
• ECX337 from Sony needs 10V
• Torex power modules helped save space too by being stacked on top of the inductor
• Sony uses LVDS (FPDlink) and not MIPI
• Offloaded processing to a phone or computer
• Power
• Wi-Fi vs bluetooth
• New goal is to minimize power during processing, now it’ll be efficiency around WiFi and Display
• With OLEDs you can selectively turn on pixels
• Goal for the battery is 8 hours for “all day”
• What is Aedan’s “requirements space” and what’s driving it?
• Cost has become a concern for new boards
• Using an assembly house to have one known-good assembly board
• What’s on the new board?
  • The new display has MIPI DSI
    • The display doesn’t support 2 lane DSI out of the box
    • Displays are sometimes configurable in terms of how many lanes with registers
    • What do the lanes refer to? Each pair (“Data lane”) is a differential pair
    • Most displays will do 4 lanes (8 conductors) at 1Gbps
    • “Giganibbles per second”
    • Silicon backplane with OLED on top
    • ViewTrix
  • The processor is the NXP iMX RT500
    • “This is design is made for Garmin”
    • Aedan is coding it in Zephyr
    • Drivers are in MCUexpresso
    • DCnano display driver in Zephyr
    • no GPU driver in Zephyr
    • 2D GPU in the chip
  • WiFi module is the same as the past rev, the Si Labs WFM200S
    • Sending compressed data over the WiFi link
  • Mechanical
    • Tweaking displays and 3D printed mounts
    • Prism
    • Flex cables
    • XReal / NReal
    • Using your brain as the combiner
• Zach from Voidstar
• Aedan just went to the Augmented World Expo in May. “No one was wearing an AR display around the conference”
• Vision for the future
• Follow Aedan online
  • GitHub
  • Twitter