pico-xvc

This project implements a Raspberry Pico based Xilinx Virtual Cable (XVC). It allows using Raspberry Pico as a JTAG adapter for programming Xilinx FPGAs.

It is derived from the excellent pico-dirtyJtag project.

A special shoutout goes to https://github.com/tom01h for crazily improving the performance of this project - thank you!

The pinout is as follows (it maches the pin names of the target device's JTAG port, in other word - you DON'T need to swap TDI and TDO pins like you would do with the interfaces like SPI or UART):

Pin name	GPIO
TDI	GPIO16
TDO	GPIO17
TCK	GPIO18
TMS	GPIO19
GND	Pin 23

Note: The Raspberry Pico is a 3.3v device. Ensure that the target device and the Pico are electrically compatible before connecting them.

Compatibility tests

The project has been verified to be working with the following hardware and software combinations:

Programmer Board	Firmware	Target	Software	Date
Raspberry Pi Pico	xvc-pico	EBAZ4205 'Development' FPGA Board	Vivado 2021.1	August 2021
Raspberry Pi Pico	xvc-pico	EBAZ4205 'Development' FPGA Board	Vivado ML Standard 2023.1	May 2023
Raspberry Pi Pico W	xvc-pico-wifi	Unknown	Vivado v2023.1 (64-bit)	April 2024
Raspberry Pi Pico	xvc-pico	Coolrunner II XC2C64A (Matrix Glitcher)	Xilinx ISE 14.7 (Linux x64)	August 2024

Building pico-xvc (for Linux users)

Shortcut: Upload the pre-built xvcPico.uf2 file to the Raspberry Pico Board. Done - skip to the next section.

Install dependencies:

sudo apt install cmake gcc-arm-none-eabi libnewlib-arm-none-eabi \
  libstdc++-arm-none-eabi-newlib git libusb-1.0-0-dev build-essential \
  make g++ gcc

mkdir ~/repos
cd ~/repos

git clone https://github.com/raspberrypi/pico-sdk.git
cd pico-sdk; git submodule update --init

cd ~/repos
git clone https://github.com/kholia/xvc-pico.git

Build the host-side daemon:

cd ~/repos/xvc-pico/daemon
cmake .
make
sudo ./xvcd-pico  # run on the host computer, turn on the pico board before

Build the Raspberry Pico's firmware:

cd ~/repos/xvc-pico/firmware
export PICO_SDK_PATH=${HOME}/repos/pico-sdk
cmake .
make -j4

Windows Notes

Grab xvcd-pico.exe from the builds folder of this repository itself.

You need to install the libusbK driver with Zadig (https://zadig.akeo.ie/).

OR

You can install the WinLibUSB driver from USB Drive Tool Application (https://visualgdb.com/UsbDriverTool/).

Credit goes to https://github.com/benitoss/ for these instructions.

Usage

On the host computer with the Raspberry Pi Pico connected, run the XVC Daemon Server.

./xvcd-pico

In Vivado, select the Add Xilinx Virtual Cable (XVC) option in the Hardware Manager and mention the IP address and the Port of the host computer.

Tips

If you see the End of startup status: LOW error message in Vivado, check the FPGA power supply's voltage and current ratings.

I found Maker Pi Pico Base really helpful for debugging GPIO stuff.

This URL says that Xilinx Virtual Cable (XVC) protocol allows (local or remote) Vivado to connect to a target FPGA for debug leveraging standard Xilinx standard debug cores like Integrated Logic Analyzer - ILA, Virtual Input/Output - VIO, and others. ILA works fine over our Raspberry Pico JTAG adapter. Vitis stuff is also supported.

Rough Performance Stats ("Speed")

If cost and ease-of-availability are the driving constraints (at the cost of speed), then this project is 'usable' and can probably suffice. If higher programming speed is a requirement, I recommend using xc3sprog or openFPGALoader with an FT2232H board.

This project might be one of the cheapest, most energy-efficient Vivado-Compatible JTAG programmers. I use this project as my "daily driver" now ;)

Writing ebaz4205_top.bit (371.6 KiB) takes only ~2.5 seconds now - thanks to tom01h. Don't overestimate the speed of human programmers and Vivado though ;)

$ time ./openFPGALoader -c xvc-client --port 2542 --file-type bin ebaz4205_top.bin
empty
detected xvcServer version v1.0 packet size 12288
freq 6000000 166.666667 166 0
a6 0 0 0
Open file DONE
Parse file DONE
load program
Load SRAM: [==================================================] 100.00%
Done
./openFPGALoader -c xvc-client --port 2542 --file-type bin ebaz4205_top.bin  0.00s user 0.01s system 0% cpu 7.389 total

It seems openFPGALoader is a lot slower than Vivado in programming devices via XVC!?

Writing corescore_0.bit (2 MiB) which uses ~100% FPGA LEs takes around ~9 seconds.

Flash FPGA without Vivado

./openFPGALoader -c xvc-client --port 2542 --file-type bin ebaz4205_top.bin

USB UARTs

Connect Pico's hardware UART pins to FPGA's UART.

#define UART_TX_PIN 0
#define UART_RX_PIN 1

Set UART of FPGA to 115200 baud rate.

Note: /dev/ttyACM(n) will appear when Pico's USB is connected.

Related Ideas / Projects

• https://github.com/kholia/xvcpi
• https://github.com/kholia/xvc-esp32
• https://github.com/kholia/xvc-esp8266
• https://github.com/phdussud/pico-dirtyJtag/
• https://github.com/kholia/Colorlight-5A-75B
• https://github.com/fusesoc/blinky#ebaz4205-development-board