USB PD monitor implemented in a Tang Nano 9K FPGA board. USB-PD packet data is decoded from the CC pins and then sent out the FPGA as UART TX data. The Tang Nano 9K's USB-to-UART bridge (software FTDI FT2232C running on the BL702 IC) can be accessed with Python to see the packet data. The only physical connections needed are CC1, CC2 and their ground pins. The Tang Nano 9K is powered by the USB connection to the host computer. Using the 1.8V pins, this FPGA board is able to monitor the USB-PD messages on the CC pins without any levelshifters.

See fpga/src/tang_nano_9k_generic.cst for pins used. 3.3V buffered CC1 and CC2 outputs are available to veiw with a logic analyzer (I highly recommend the $12 Saleae clones on Amazon.com, as sigrok pulseview has full USB PD decoding). I also have a 3.3V buffered "uart_tx_buf" signal which can connect to a logic analyzer or another serial-to-usb adapter.

Tang Nano 9k board Info: https://wiki.sipeed.com/hardware/en/tang/Tang-Nano-9K/Nano-9K.html

I used the eLabBay USB C passthrough breakout board: https://elabbay.myshopify.com/products/usb3-1-cm-cf-v1a-usb3-1-type-c-male-to-female-pass-through-breakout-board

Here are some captures from Sigrok's Pulseview using my HiLetgo $12 logic analyzer:

D0 is the buffered 3.3V version of the CC pin data. D1 is the 3.3V uart_tx_buf that the FPGA sends to the USB-to-UART bridge IC on the Tang Nano board. Pulseview is able to fully decode the 3.3V CC pin data.