#515 – Embedded Linux with Jay Carlson

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Welcome Jay Carlson!

• The new article “So you want to build an embedded Linux system” is 35,000 words. Why not a book?
• Friend of the show Drew Fustini was on embedded last week talking about building Linux
• Jason and Robert from BeagleBoard.org on TAH
• “I’m your classic electrical engineer”
• For the aforementioned article, Jay designed 10 boards with different application microprocessors.
• Took 3 hours on the software side
• Tweeted about baremetal vs linux

The difference between bare-metal and embeded Linux development:
Bare-metal: read documentation and write your own code.
Embedded Linux: read code and write your own documentation.

— ᴊᴀʏ ᴄᴀʀʟsoɴ (@jaydcarlson) October 7, 2020

• Device tree
• Operating system
• Object files in C
• POSIX
• A33
• UBoot, Yocto, Buildroot
• Building for the A33
• Git repo
• Olinuxino A33 board
• Erik Larson on the Contextual Electronics Podcast
• Want a good exercise for learning the build system? Change where the UART is located
• What if they don’t know linux?
• “I just break stuff and cycle around and keep trying”
• Twitter thread about linux shell commands
• V3S Allwinner
• Hackaday podcast talked about the 0.8mm pitch parts
• Using higher grade parts to get more margin on (memory) parts
• $50 bucks and a weekend
• “Just try it”
• 10 breakout board with parallel board
• Adding a new driver
• NUC980 internal RAM
• Student stories
  • Spotify daemon
  • Networking is “free”
  • SDIO wifi module for $0.60
  • Set top box example
• Jay and Chris discuss a theoretical project, like a sous vide with a cap touch screen
• How big is the screen? With most of the 10 boards shown, they’d be OK up to 5″
• Newer displays have MIPI
• Most parts are older and have parallel interfaces (which can be an EMI risk)
• MP1 and A33 only have MIPI
• LVDS
• Video of the QT5 demo
• iMX8 is another category of layout
• Robert Ferenec course
• NUC
• Research lab at Univ Neb – Lincoln
• Occult tracking of pigs
• When do you switch down to a micro?
• STM32F7
• Power considerations
• $1 microcontroller article
• When should you use an RTOS?
• For most programs running on Linux, Jay recommends to wrap it in a while 1 loop.
• “Linux benefits from the whole human race”
• Combining low power and high power systems. Sometimes Jay will send data over USB (if he needs high speed transfer) or set up SPI/I2C for direct control.
• MP1 and AM335x have built in micros
• Listener questions!
• “Have any vendors contacted him to use his designs as a devkit or just permission to promote it? He mentioned working with one on GitHub for bug fixes but I think that was it.”
  • Ran a verison without serpentine traces
  • Overclocking the memory chip to try and break it
  • Vendors should use a 0.1″ form factor
• “What CAD package did he use for all of those boards?”
  • Altium
• What core elements does he try to address in the class, and as embedded systems change where does he see intro course work going?
  • Intro embedded systems class
  • Working on a platform to learn embedded systems
  • Jay talked extensively about engineering education on Embedded.fm episode 303
• Which of the three pinmux tools (NXP, TI or ST) did Jay like the most?
  • All similar
• Assume I now working hardware (an iMX6ULL series board) as a base I can work upon. After what complexity point should I consider using this embedded linux system in a project?
• Any luck interfacing with current smartphones cameras?
  • Camera modules will be raw output over MIPI
• Do you see embedded linux, combined with something like etherCat or modbusTCP, as a viable replacement for PLC machines?
  • This is the type of application the AM335x is targeted at
• How much did he use the dev board from each part before making its own board ?
  • Not much. Most went straight to proto. THe STM32MP1 dev board stinks as a SBC.
• Hard RealTime Linux for safety applications. Why is it a good idea and why it’s a horrible idea?
• How good are different silicon vendors about upstreaming their kernel patches?
  • What is upstreaming?
  • Smart cameras and rear cameras example
  • Quectel module with Android
• Why Lincoln, Nebraska?
• Yes Man
• Jay now works for Virtual Incision, a surgical robot company located in Lincoln.

You can find Jay via his website JayCarlson.net. You can also find him on twitter at @jaydcarlson.

Thanks to our Patrons for sponsoring today’s episode. You can become one of them by going to Patreon.com/TheAmpHour. A special thanks to our corporate sponsor Binho.