--- breadcrumbs: - - /chromium-os/developer-library/guides - ChromiumOS > Guides page_name: twinkie title: USB-PD Sniffer --- [TOC] ## Overview This page describes a USB-PD sniffing dongle with Type-C connectors. The dongle can be supported by Chrome devices as part of a USB-Type C implementation. image image image ## Hardware Capabilities * Sniffing USB Power Delivery traffic on both Control Channel lines (CC1/CC2) * Transparent interposer on a USB Type-C connection * Monitoring VBUS and VCONN voltages and currents (WARNING: VBUS path designed for SPR voltages up to 20V. Not appropriate for use with USB PD 3.1 EPR systems when in EPR mode) * Injecting PD packets on CC1 or CC2 * Putting Rd/Rp/Ra resistors on CC1 or CC2 [image](Twinkie-diagram.png) Complete schematics, layout, and enclosure are attached at the bottom of this page. ## **Firmware Source Code** The firmware is located In the Chromium Embedded Controller repository under *[board/twinkie/](https://chromium.googlesource.com/chromiumos/platform/ec/+/firmware-twinkie-9628.B/board/twinkie/),* the release version is on the firmware-twinkie-9628.B branch : ### **Building Firmware** Within your ChromiumOS chroot, the syntax is: ```none For the impatient, here is a very cut-down version of the detailed instructions.  ``` ```none If anything here gives you trouble, refer to the [official documentation](/chromium-os/developer-guide) instead. ``` ```none ``` ```none ## Install the prerequisite tools ``` ```none goobuntu$   sudo apt-get install git-core gitk git-gui subversion curl ``` ```none goobuntu$   git clone ``` ```none goobuntu$   export PATH=$(pwd)/depot_tools:$PATH ``` ```none ## Check out the sources ``` ```none goobuntu$   mkdir chromiumos && cd chromiumos ``` ```none goobuntu$   repo init -u https://chromium.googlesource.com/chromiumos/manifest.git \ ``` ```none                     -g minilayout -b firmware-twinkie-9628.B ``` ```none goobuntu$   repo sync ``` ```none ## Enter the chroot ``` ```none goobuntu$   cros_sdk ``` ```none ## Install the board-specific compiler toolchain ``` ```none chroot$   ./setup_board --board=falco ``` ```none ## Check out the EC sources ``` ```none chroot$  cros_workon-falco start chromeos-ec ``` ```none chroot$  repo sync ../platform/ec ``` ```none ## Build things ``` ```none chroot$ cd ../platform/ec ``` ```none chroot$  make BOARD=twinkie -j ``` Alternately, you can use the **pre-built firmware** *[twinkie_v1.11.19-9e81762f2.bin](https://storage.googleapis.com/chromeos-vpa/twinkie-20171122/twinkie_v1.11.19-9e81762f2.bin)* attached at the bottom of this page. ### **Flashing Firmware** The USB-PD dongle behaves as a USB DFU device when the ID pin is grounded on the USB micro-B connector. This is done either by plugging an A-A USB cable into an A-to-microB OTG adapter as shown in the photo below or by typing the` dfu` command on the USB console (if you already have a recent firmware, e.g. *v1.11.19*+). Within your ChromiumOS chroot: ```none ./util/flash_ec --board=twinkie ``` or on Ubuntu Linux: ```none sudo apt-get install dfu-util ``` ```none sudo dfu-util -a 0 -s 0x08000000 -D twinkie_v1.11.19-9e81762f2.bin ``` [Programming Twinkie with OTG and A-to-A cables](./twinkie_programming.jpg) if you have entered the DFU mode by using the dfu console command, you need to use the following command to exit it : sudo dfu-util -a 0 -s 0x08000000:force:unprotect -D twinkie_v1.11.19-9e81762f2.bin else plugging the regular USB cable will do it automatically. ## Using the Integrated Command Line over USB The USB-PD dongle exports its internal command-line console as a pair of USB bulk endpoints. On a Linux system, you get the console as a /dev/ttyUSB*n* device. On recent systems (kernel v3.19+), this ttyUSB device should be instantiated automatically, or other systems you can try using the *usbserial* kernel module : ```none echo '18d1 500A' | sudo tee /sys/bus/usb-serial/drivers/generic/new_id ``` If this fails, you might need to run `sudo modprobe usbserial` first. ## Using as a PD Packet Sniffer You can use the opensource [Sigrok](http://sigrok.org) framework to acquire and decode USB Power Delivery traces with the USB-PD dongle. You can then use [Pulseview ](http://sigrok.org/wiki/PulseView)to display them. The patches for the Sigrok hardware driver for the dongle is not in the upstream packages yet. The packages below also include the bleeding edge version of Pulseview which has a convenient "Tabular Decoder Output View". If your machine has an x86_64 processor, you can try the following experimental pre-built packages: - for Ubuntu Focal Fossal (20.04 LTS) ```none cd $(mktemp -d) wget https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_20.04/libsigrok4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_20.04/libsigrokcxx4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_20.04/libsigrokdecode4_0.5.3-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_20.04/sigrok-cli_0.7.1-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_20.04/pulseview_0.5.0~git20200910+1acc207a-1_amd64.deb sudo dpkg -i *.deb sudo apt-get install -f ``` - for Ubuntu Bionic Beaver (18.04 LTS) ```none cd $(mktemp -d) wget https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_18.04/libsigrok4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_18.04/libsigrokcxx4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_18.04/libsigrokdecode4_0.5.3-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_18.04/sigrok-cli_0.7.1-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/ubuntu_18.04/pulseview_0.5.0~git20200910+1acc207a-1_amd64.deb sudo dpkg -i *.deb sudo apt-get install -f ``` - for Debian Buster (stable) or ChromeOS Crostini container ```none cd $(mktemp -d) wget https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/debian-buster/libsigrok4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/debian-buster/libsigrokcxx4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/debian-buster/libsigrokdecode4_0.5.3-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/debian-buster/sigrok-cli_0.7.1-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/debian-buster/pulseview_0.5.0~git20200910+1acc207a-1_amd64.deb sudo dpkg -i *.deb sudo apt-get install -f ``` - for Rodete ```none cd $(mktemp -d) wget https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/rodete/libsigrok4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/rodete/libsigrokcxx4_0.5.2-2+twinkie_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/rodete/libsigrokdecode4_0.5.3-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/rodete/sigrok-cli_0.7.1-1_amd64.deb \     https://storage.googleapis.com/chromeos-vpa/twinkie_20201028/rodete/pulseview_0.5.0~git20200910+1acc207a-1_amd64.deb sudo dpkg -i *.deb sudo apt-get install -f ``` If you want to do a full build from sources of sigrok and pulseview with Twinkie support, now the USB PD protocol decoder is now upstreamed in libsigrokdecode (and sigrok-cli / pulseview are working out-of-the-box). You only need to add the Chromium Twinkie hardware driver in libsigrok : [last version of the patch applying on libsigrok-0.5.2](https://github.com/vpalatin/libsigrok/commit/8147e36b8ffa48a23cf898332c351f6a6d85484b) [plus the VBUS support](https://github.com/vpalatin/libsigrok/commit/97a7e9cbb3126aa5329b96a2f017e682b9036d8f) A recipe to do this build is written down in [Build Sigrok and Pulseview from sources](/chromium-os/developer-library/guides/hardware-schematics/twinkie/build-sigrok-and-pulseview-from-sources). ### Capturing traces with the Sigrok tool ```none sigrok-cli -d chromium-twinkie --continuous -o test.sr ``` ### Real-time decoding of USB PD packets while capturing ```none sigrok-cli -d chromium-twinkie --continuous -P usb_power_delivery:cc=CC1:fulltext=yes -P usb_power_delivery:cc=CC2:fulltext=yes -A usb_power_delivery=text ``` ### Displaying and decoding PD traces ```none pulseview test.sr & ``` Add the **USB PD** decoder from the Decoders menu, then edit the instantiated decoder to select the appropriate CC line. [image](./pulseview_3packets.png) [image](./pulseview_zoom_packet.png) [image](./pulseview_VBUS_V.png) [image](./pulseview_VBUS_V_A.png) ### Experimental VBUS analog traces As shown on the pictures above, you can try to capture the VBUS analog voltage and current along with the CCx lines traffic. This feature is still *experimental and might have negative side effects* on your PD packets capture ! Capturing VBUS voltage only and CCx traffic: ```none sigrok-cli  -d chromium-twinkie:analog_channels=1 --continuous -o testvbusV.sr ``` Capturing VBUS voltage and current and CCx traffic: ```none sigrok-cli  -d chromium-twinkie:analog_channels=2 --continuous -o testvbusVA.sr ``` then you can display the .sr files in Pulseview. ## Using as a Power Sink 1. Use the tw sink command. Exit sink mode by using the reboot command. 2. When a power source is detected, the dongle negotiates a power contract, activating the green LED for 5V, the red LED for 20V, or the blue LED for other voltage. 3. You can change the maximum negotiated voltage with the following command in the dongle USB shell: pd 0 dev 12 This example sets a limit of 12 V.