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Explore Google Chromium USB Type-C example designs using GoArks USB – C Thru

Explore Google Chromium USB Type-C example designs using GoArks USB – C Thru
by Rajaram Regupathy on 03-12-2016 at 12:00 pm

One of the early adopters of USB Type-C and USB Power Delivery is Google for their Chromium projects. More interestingly Google shared the complete design of the USB Type-C products in public domain right from schematic to source code of the solutions. This article explores how to use USB C-Thru board to explore Google’s designs there by enabling you to develop custom USB Type-C design of your own.
This article enables you to make your own Google USB-PD Sniffer aka “Twinkie” using USB C-Thru and a STM32 development board for just 65$ in 3 steps

Hardware requirements:

[LIST=1]

  • USB C-Thru (www.goarks.com) from https://www.crowdsupply.com/goarks/usb-c-thru
  • STM32F072B development kit from distributor. (http://www.mouser.in/search/ProductDetail.aspx?R=0virtualkey0virtualkeySTM32F072B-DISCO)

    Step – 1: Preparing software and firmware binary for Google’s USB PD Sniffer


    Figure 1: List of USB Type-C design examples from Chromium website

    Step – 2: Setting up Hardware STM32F072B-DISCO with USB C-Thru
    Having setup the necessary software and flashing the board with firmware, let us explore how to setup the hardware to build a Twinkie.


    Figure 2: Schematic of Twinkie indicating CC pins

    • Now connect pins PA1(grey), PA3(orange) and ground(black) from the STM32 board to USB C-Thru( PA1 to CC1, PA3 to CC2) as shown in the Figure-3 below:


    Figure 3: Schematic of Twinkie indicating CC pins

    • This setup gives you a part of the Twinkie design that is sufficient to act as a USB PD sniffer.

    Step – 3: Start sniffing USB PD data with homemade sniffer
    With USB C-Thru board and STM32 discovery board we have the sniffer ready to get deployed for debugging. In the example setup I am using a laptop with a USB Type-C charger and USB-C Thru based Sniffer connected to my Ubuntu PC.

    • Using a USB2.0 mini cable connect the STM32 development board to the host PC in which the Google’s USB PD sniffer software was setup (Step 1). A “lsusb” on the host PC shows the USB PD Sniffer as shown in the Figure-4 below:


    Figure 4: Enumeration of STM32 development board as Twinkie device

    • Plug USB C-Thru to the laptop and the USB Type-C Charger to the receptacle end of the USB C-Thru as shown in Figure-5 below:


    Figure 5: Google’s USB Type-C example design Twinkie implementation usingUSB C-Thru and STM32

    Conclusion

    This article provided a quick walk through of how to use USB C-Thru board with an existing development kit and make your own USB Type-C example design. You can explore other Chromium USB Type-C design examples in similar manner with few wire wrapped electronics or a breadboard setup.

    You can order USB C-Thru ( www.goarks.com ) from https://www.crowdsupply.com/goarks/usb-c-thru and write to us for any clarifications at info@goarks.com


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