ESP8266 programming and debug via J-Link ??

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Joined: Fri Jan 22, 2016 3:11 am

ESP8266 programming and debug via J-Link ??

Postby gigel » Fri Jan 22, 2016 5:26 am

Is it possible, and if yes, did anyone succeed in programming and debugging ESP8266 using a J-Link via either JTAG or SWD?

I am using a Sparkfun Thing board ( ... _Thing.pdf ), and writing code from within MS Visual Studio + GDB, debug method via XtensaOCD or OpenOCD.

I attached a Segger J-Link ( ) to the Sparkfun Thing board, but can't detect the CPU core.

JTAG signal TMS ==> ESP8266 pin 14
JTAG signal TDI ==> ESP8266 pin 12
JTAG signal TCK ==> ESP8266 pin 13
JTAG signal TDO ==> ESP8266 pin 15 (after removing R17 pull-down on SparkFun Thing board)
JTAG signal RST ==> ESP8266 pin RST (DTR line on SparkFun Thing board)

Btw, why is GPIO15/MTDO pulled down on the SparkFun Thing board?

I would appreciate any guidance on this topic.


Posts: 25
Joined: Fri Oct 24, 2014 7:58 pm

Re: ESP8266 programming and debug via J-Link ??

Postby ESP_Sprite » Mon Jan 25, 2016 5:19 pm

GPIO15 is pulled down because it is a bootstrap pin that changes the boot mode of the ESP.

What software are you using, and are you sure this software supports the Xtensa LX106 core in the ESP8266?

Posts: 140
Joined: Mon Oct 27, 2014 10:40 am

Re: ESP8266 programming and debug via J-Link ??

Postby Espressif_Kelly » Wed Feb 03, 2016 11:09 am

Dear gigel,

Current ESP8266EX does not support the hardware debug tools,like JTAG. So you need to debug by log print.

BTW, we are planning to realize JTAG funtiocn on ESP8266EX.


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Joined: Tue May 02, 2017 11:03 pm

Re: ESP8266 programming and debug via J-Link ??

Postby dev01 » Tue May 02, 2017 11:06 pm

Are there any new developments regarding HW debugging with JLink?

rajkumar patel
Posts: 12
Joined: Fri Mar 03, 2017 8:20 pm

Re: ESP8266 programming and debug via J-Link ??

Postby rajkumar patel » Fri Jun 30, 2017 2:14 pm

hi esp_team,

which is powerful tool or method for esp8266 debugging?

for esp32 there's no issue as xtesnsa addr2line tool is tracing back with great accuracy for reset cause from dump file but this isn't the case with my esp8266 WROOM2 module. sometimes i get the cause and most of the time i left unanswered while going for this tool for esp8266.

but finding rootcause of board reset is my prime requirement.
i'm not sure whether i should go for GDBSTUB or openOCD for hardware debugging. is any of this going to help me anyway?
that would be great for me and plenty of others if you share your suggestions on this.
i'm totally a newbie to this debugging thing.


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