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https://github.com/derekmulcahy/xvcpi
Xilinx Virtual Cable Server for Raspberry Pi
https://github.com/derekmulcahy/xvcpi
jtag snickerdoodle xilinx-fpga xilinx-vivado zynq
Last synced: about 1 month ago
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Xilinx Virtual Cable Server for Raspberry Pi
- Host: GitHub
- URL: https://github.com/derekmulcahy/xvcpi
- Owner: derekmulcahy
- License: cc0-1.0
- Created: 2017-04-19T15:14:20.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2022-03-14T02:41:18.000Z (almost 3 years ago)
- Last Synced: 2024-08-02T01:16:31.414Z (5 months ago)
- Topics: jtag, snickerdoodle, xilinx-fpga, xilinx-vivado, zynq
- Language: C
- Size: 290 KB
- Stars: 104
- Watchers: 10
- Forks: 24
- Open Issues: 1
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Xilinx Virtual Cable Server for Raspberry Pi
[Xilinx Virtual Cable](https://github.com/Xilinx/XilinxVirtualCable/) (XVC) is a TCP/IP-based protocol that acts like a JTAG cable and provides a means to access and debug your FPGA or SoC design without using a physical cable.
A full description of Xilinx Virtual Cable in action is provided in the [XAPP1252 application note](https://www.xilinx.com/support/documentation/application_notes/xapp1251-xvc-zynq-petalinux.pdf).
**Xvcpi** implements an XVC server to allow a Xilinx FPGA or SOC to be controlled remotely by Xilinx Vivado using the Xilinx Virtual Cable protocol. **Xvcpi** uses TCP port 2542.
The **xvcpi** server runs on a Raspberry Pi which is connected, using JTAG, to the target device. **Xvcpi** bitbangs the JTAG control signals on the Pi pins. The bitbanging code was originally extracted from [OpenOCD](http://openocd.org).
XVCPI has been revised to use the bcm_host library. This automatically configures the peripheral IO addresses for the various hardware versions of the Raspberry PI SOC. See the [Raspberry Pi Hardware Manual](https://www.raspberrypi.com/documentation/computers/raspberry-pi.html#peripheral-addresses) for detailed information.
# Wiring
Note: The Raspberry Pi is a 3.3V device. Ensure that the target device and the Pi are electrically compatible before connecting. 100 Ohm resistors may be placed inline on all of the JTAG signals to provide a degree of electrical isolation.
JTAG uses 4 signals, TMS, TDI, TDO and, TCK.
From the Raspberry Pi perspective, TMS, TDI and TCK are outputs, and TDO is an input.
The pin mappings for the Raspberry Pi header are:
```
TMS=GPIO25, TDI=GPIO10, TCK=GPIO11, TDO=GPIO9
```
In addition a ground connection is required. Pin 20 is a conveniently placed GND.
The same pins are also used by [Blinkinlabs JTAG Hat](https://github.com/blinkinlabs/jtag_hat). This JTAG Hat accomodates target devices with voltage levels between 1.8V and 5V by using buffers.
Note that the XVC protocol does not provide control of either SRST or TRST and **xvcpi** does not support a RST signal.
# Usage
Start **xvcpi** on the Raspberry Pi. An optional -v flag can be used for verbose output.
The JTAG interface speed can be controlled by specifiying an integer delay after the -d flag.
The maximum speed is dependent on the speed of the Pi, the quality of the connections and the target device.
Delay values from 200 to 1000 work well. Smaller is faster, larger more reliable!
Vivado connects to **xvcpi** via an intermediate software server called hw_server. To allow Vivado "autodiscovery" of **xvcpi** via hw_server run:
```
hw_server -e 'set auto-open-servers xilinx-xvc::2542'
```
Alternatively, the following tcl commands can be used in the Vivado Tcl console to initiate a connection.
```
open_hw
connect_hw_server
open_hw_target -xvc_url :2542
```
Full instructions can be found in [ProdDoc_XVC_2014 3](ProdDoc_XVC_2014_3.pdf).
# Snickerdoodle
The initial purpose of **xvcpi** was to provide a simple means of programming the [Snickerdoodle](http://snickerdoodle.io).
# Licensing
This work, "xvcpi.c", is a derivative of "xvcServer.c" (https://github.com/Xilinx/XilinxVirtualCable)
"xvcServer.c" is licensed under CC0 1.0 Universal (http://creativecommons.org/publicdomain/zero/1.0/)
by Avnet and is used by Xilinx for XAPP1251.
"xvcServer.c", is a derivative of "xvcd.c" (https://github.com/tmbinc/xvcd)
by tmbinc, used under CC0 1.0 Universal (http://creativecommons.org/publicdomain/zero/1.0/).
Portions of "xvcpi.c" are derived from OpenOCD (http://openocd.org)
"xvcpi.c" is licensed under CC0 1.0 Universal (http://creativecommons.org/publicdomain/zero/1.0/)
by Derek Mulcahy.