WIFI-JTAG

ESP8266 (ESP-12) for $4 as WiFi JTAG adapter. This could be the simplest, the cheapest and the slowest JTAG adapter. This WIFI-JTAG needs openocd to work, but I also offer a standalone LibXSVF-ESP JTAG.

Note: Some time has passed so dependencies changed both at ESP8266 TCP stack and openocd, so this project might not work out of the box (as it did before :-).

Here's arduino code for ESP8266 which listens to TCP port 3335 and talks remote_bitbang protocol with OpenOCD http://openocd.org over WiFi and usb-serial port version of the same, for use with any arduino (without WiFi).

It can upload SVF bistream over WiFi network to the FPGA. more on http://www.nxlab.fer.hr/fpgarduino/linux_bitstreams.html

Tested and working on FPGA boards TB276 (Altera Cyclone-4) and TB299 (Xilinx Spartan-6)

interface remote_bitbang
remote_bitbang_port 3335
remote_bitbang_host jtag.lan
jtag newtap tb276 tap -expected-id 0x020f10dd -irlen 10
init
scan_chain
svf -tap tb276.tap project.svf
shutdown

OpenOCD log of remote_bitbang JTAG adapter made with Arduino ESP8266.

Warn : Adapter driver 'remote_bitbang' did not declare which transports it allows; assuming legacy JTAG-only
Info : only one transport option; autoselect 'jtag'
adapter speed: 1000 kHz
Info : Initializing remote_bitbang driver
Info : Connecting to jtag.lan:3335
Info : remote_bitbang driver initialized
Info : This adapter doesn't support configurable speed
Info : JTAG tap: tb276.tap tap/device found: 0x020f10dd (mfg: 0x06e, part: 0x20f1, ver: 0x0)
Warn : gdb services need one or more targets defined
   TapName             Enabled  IdCode     Expected   IrLen IrCap IrMask
-- ------------------- -------- ---------- ---------- ----- ----- ------
 0 tb276.tap              Y     0x020f10dd 0x020f10dd    10 0x01  0x03
shutdown command invoked
Info : remote_bitbang interface quit

What works for one FPGA, doesn't neccessary work for the other. For example, it didn't work for Lattice ECP3 LFE3-150EA.

TCP-Serial

By simply pressing ENTER in telnet session Wifi-jtag will enter tcp-serial bridge mode, thus allowing remote serial communication to FPGA over WiFi. Serial break may be issued with ctrl-@ at start of telnet session. Serial break resets FPGArduino F32C CPU and enters bootloader, which can accept a hex or binary executable file.

telnet jtag.lan 3335
ctrl-]
telnet> mode char
ctrl-@
mi32l>
mi32l>
mi32l>

virtual serial port:

socat -d -d pty,link=/dev/ttyS5,raw,echo=0  tcp:xilinx.lan:3335

sending ascii file over tcp. (executable compiled hex file). For serial break to enter bootloader before upload, first char of the file should be a null char (ascii 0 aka \0)

socat -u FILE:blink.cpp.hex TCP:jtag.lan:3335

Pinout

The pinout with standard TXD and RXD:

TDO=14, TDI=16, TCK=12, TMS=13, TRST=4, SRST=5, TXD=1, RXD=3, LED=15

Alternate serial pinout can be defined at compile time:

TXD=15, RXD=13

PIN	nodemcu	ESP-12	ESP-201	wire	TB276 10-pin	TB299 14-pin
GND	GND	GND	GND	black	10	1,3,5,7,9,11,13
TMS	D0	GPIO16	XPD	violet	5	4
TCK	D5	GPIO14	1014	yellow	1	6
TDO	D6	GPIO12	1012	green	3	8
TDI	D7	GPIO13	1013	blue	9	10
VCC	3V3	VCC	3.3V	red	4	2
TXD0	D10	TXD or GPIO1	TX	orange	RXD 133	RXD 94
RXD0	D9	RXD or GPIO3	RX	white	TXD 129	TXD 97
GND		GPIO15 or NC	1015	15k
VCC		EN or CH_PD	CHIP_EX	15k
VCC		GPIO0 or NC	100	15k
VCC		GPIO2 or NC	102	15k
VCC		REST	RST	15k

Warning: Some ESP-12 modules and breakout boards have GPIO4 and GPIO5 swapped and wrong labeling for them. If it doesn't work, try swapping GPIO4 and GPIO5. See ESP8266 family pinouts: http://www.esp8266.com/wiki/doku.php?id=esp8266-module-family

Avoid connecting GPIO 0, 2, 15 (and 16 on some ESP) to target FPGA, as those pins need to be at some default state during first second of power on for ESP8266 to boot firmware. If it doesn't boot, they need to be disconnected during first second of powering up the ESP8266.

TRST and SRST are reset signals usually used for ARM debugging. Most FPGA don't need them. LED may be left unconnected too. WiFi-JTAG board can be directly powered from JTAG connector.

We recommend ESP-12 or nodemcu as they have plenty of free GPIO. They need external usbserial to flash them, see next section "Flashing".

"nodemcu-devkit" board has onboard 3.3V serial over micro usb: https://github.com/nodemcu/nodemcu-devkit but if TXD/RXD need to be used to communicate with FPGA then TXD must be GPIO15 and manually disconnected during power up.

ESP-201 works too. uploads f32c bitstream in half a minute.

Flashing

To flash firmware into ESP8266 connect 3.3V USBSERIAL adapter:

USBSERIAL	wire	ESP-12	ESP-201
GND	black	GND	GND
GND	1k	GPIO15	1015
VCC	1k	EN or CH_PD	CHIP_EX
VCC	red	VCC 3.3V	3.3V
RXD	orange	TXD	TX
TXD	white	RXD	RX
DTR	green	GPIO0	100
RTS	yellow	REST	RST

Compiling

Precompiled binary is available in bin/

Default SSID is "jtag" and password "12345678" (without quotes), adapter will act as access point.

It has to be compiled to change SSID and PASSWORD and to select access point or client mode.

To compile from source you need ESP8266 Arduino. Download from http://arduino.cc and unpack arduino-1.6.5 or higher. Then add support for ESP8266

Here is the github project https://github.com/esp8266/Arduino use ESP8266 Arduino (stable, Jul 23, 2015),

Automatic installation using JSON is avaialble in File->Default Settings->Additional Boards Manager URLs enter:

http://arduino.esp8266.com/stable/package_esp8266com_index.json

Select pull down menu Tools->Board->Board Manager and instal ESP8266 (cca 30MB). Read more on https://github.com/arduino/Arduino/wiki/Unofficial-list-of-3rd-party-boards-support-urls#list-of-3rd-party-boards-support-urls

Select pull down menu Tools->Board->Board Manager and instal ESP8266 (cca 30MB).

If you have ESP-12 or old nodemcu, choose board "Generic ESP8266 Module" or "NodeMCU 0.9 (ESP-12)".

If you have ESP-12E, ESP-201 or new nodemcu, choose board "NodeMCU 1.0 (ESP-12E)"

Speed

JTAG upload is slow because OpenOCD creates network traffic with short packets of 1-3 bytes sending to and from WiFi-JTAG. Watch the traffic:

tcpdump -A port 3335

Switching direction from receive to transmit takes time 1-300 ms.

Time uploading FPGArduino https://github.com/f32c

750KB SVF file to TB276 (Altera Cyclone-4)
WiFi esp8266/arduino     : 0:27 minutes
Serial 230400 baud       : 4:20 minutes

1.4MB SVF file to TB299 (Xilinx Spartan-6)
WiFi esp8266/arduino     : 0:24 minutes

Reliability

Firmware is useable but not completely stable. After one JTAG TCP connection, it is good to wait few seconds for the sockets to close properly before next connection. It may sometimes stop responding when just connected to WiFi access point even if JTAG is not used. We recommend to power it on just before use.

Improvement

There is much room for improvement of course: network protocol from OpenOCD could be optimized to allow longer packets, buffering, compression (instead of sending same sequence many times), use some hardware optimization in the ESP8266 like SPI as JTAG accelerator, or SVF player approach from JTAGWhisperer.

LUA (not useable)

LUA version of the above does the same protocol but in practice it will not work for longer transfers, only boundary scan. TCP disconnects within a minute. It is here just as a proof-of-concept.

Similar JTAG projects:

Xilinx virtual cable in ESP nodemcu LUA https://github.com/wzab/esp-wifi-xvc http://forums.xilinx.com/t5/Configuration/Problems-with-XVC-plugin-both-in-ISE-Impact-and-in-Vivado/m-p/631321

JTAG SVF player https://github.com/sowbug/JTAGWhisperer

Xilinx virtual cable https://github.com/gtortone/esp-xvcd https://github.com/Xilinx/XilinxVirtualCable https://github.com/tmbinc/xvcd

FT232R bitbang http://vak.ru/doku.php/proj/bitbang/bitbang-jtag

JTAGduino https://github.com/balau/JTAGduino