More on Segger J-Link and VisualGDB.

In my previous post, I explained the problem of J-Link JTAG drivers being changed by OpenOCD in VisualGDB, and my difficulty in putting back the proper drivers for use by Segger utilities.

Since posting this information to twitter and sysprogs forums, I've learned some interesting (and cool) things:

1) The clever folks at Sysprogs have their own "zadig-like" USB driver tool (strategically called USBDriverTool), that unlike zadig, has a "put back the original drivers" feature:

And can be downloaded (free!) here:

http://visualgdb.com/UsbDriverTool/

2) Additionally - the kind support folks at Segger responded to my email and pointed out that VisualGDB also supports talking to the Segger GDB server directly (instead of using OpenOCD). There's even an excellent example:

https://visualgdb.com/tutorials/arm/stm32/

Note in particular that instead of picking the J-Link device from the OpenOCD Debug method drop-down list, that there's a "J-Link JTAG" debug method also listed!

3) The Segger folks also have an explanation on the J-Link showing up as a BULK device in Windows. This is not a problem I had, but I am including this as relevant:

https://wiki.segger.com/J-Link_shown_as_generic_BULK_device_in_Windows

The screen snips there appear to be from an earlier version of Windows. Additionally, as noted in my proir post - simply selecting "Update Driver" would result in Windows saying that the drivers are already the current ones (even though it does not work). So you may need to delete the drivers before attempting the update when seeing this "BULK" driver issue.

Gizmo Compatibility

I'll be keeping track of my gizmo compatibility here.

See also: https://github.com/gojimmypi/Gizmos

	Atmel ICE	Bus Blaster	Bus Pirate	Olimex ARM-USB-OCD-H	Segger J-Link EDU	ST ST-Link V2	USB-ASP 2.0 (red)
Arduino Uno	-	-	-	(no jtag)	(no jtag)	(no jtag)	-
Arduino Due	-	-	-	(no jtag)	(no jtag)	(no jtag)	-
"Blue Pill" STM32F103C8T6
ESP32	-	-	-	-	-	no	-
ESP8266	-	-	-	-	-	-	-
STM32 Smart V2 STM32F103	-	-	-	-	-	yes	-
Wemos ESP8266	-	-	-	-	-	-	-

JTAG Debugging for ESP32

Notes and information on JTAG Debugging the ESP32 WROOM-32 (aka DevKitC, aka ESP32_Core_Board_V2)

I started off my day thinking I'd take my ESP32 for a JTAG test drive. Searching for pinouts I quickly realized there are known bad pinouts floating around. This was quite a surprise as the ESP32 has been out for well over a year. I wasted a ton of time on that. I'm posting my findings here.

As one might expect - the Adafruit pinout appears to be the most accurate one:



WROOM-32 ESP32 Pinout

 from: https://cdn-shop.adafruit.com/product-files/3269/pinout_wroom_pinout.png

(many thanks to the folks at @esp32net for responding to my tweet and helping to identify correct pinout).

So if you happen to see the pinout on the sparkfun site, the information is WRONG (hopefully they will correct it soon):

https://www.sparkfun.com/news/2017 (bad pinout here!)

I modified a known-good pinout image to create this little reference to easily identity a bad ESP32 pinout. Hint: look for the locations of the GND pins.



Not all online pinouts are accurate. Here's where to find proper GND on ESP32



Really, the ultimate authority is of course the Espressif data sheet:

http://www.espressif.com/sites/default/files/documentation/esp_wroom_32_datasheet_en.pdf

The PDF has this pinout overview, with the functions listed in a table on the following pages of the PDF:

See also the Espressif ESP-IDF docs on GitHub:

https://github.com/espressif/esp-idf/blob/master/docs/openocd.rst

Ok, so once the correct pinout is found - there was a moment of "oh no, all the JTAG pins are not available on my CoreBoard V2 breakout (grumble, grumble I don't want to solder them on)". But no... all good. Who would think that SD2 = TCK?

I should mention that "ESP32_Core_Board_V2" is the same as "ESP32-DevKitC"

Resources available here:

http://espressif.com/en/products/hardware/esp32-devkitc/resources

In particular the PDF of schematic found in "ESP32 Development Board Reference Design":

http://espressif.com/sites/default/files/documentation/esp32_development_board_reference_design.zip

found in the zip buried in this directory:

ESP32_Development_Board_Reference_Design\ESP32-DevKitC(ESP32_Core_Board_V2)\01_Schematic

I took a variety of sources and copy/pasted into a new pinout diagram for myself:

This one is the whole dev board and includes the 20 pin JTAG header, and my (arbitrary) color code:

ESP32-WROOM32 Pinout for ESP32 DevKitC / ESP32_Core_Board_V2

https://raw.githubusercontent.com/gojimmypi/ESP32/master/images/myESP32%20DevKitC%20pinout.png

So these days, I've been really enjoying the JTAG capabilities of the Sysprogs VisualGDB:

http://visualgdb.com/download/

They have a tutorial for ESP32 JTAG here:

https://visualgdb.com/tutorials/esp32/

Online tutorials are really awesome. I wonder how long it would have taken me to figure out Step 7 on my own! ha! (issue with Visual Studio/ESP-IDF framework and optimization default problem: who would have guessed?)

But that tutorial is using the Sparkfun ESP32 Thing, and mine is the Adafruit ESP32 Core Board V2, mentioned above.

Note: Although the Sparkfun apparently has an LED on GPIO5 - according to the schematics, the only LED on this board is the power LED - so don't expect it to blink - unless you are having really serious power problems! ;) But the sample code does indeed control GPIO5.

There's a recommended max of 6mA per pin on ESP32, with and absolute max of 12mA (read: you could still damage or shorten life). Many LED's run at 20mA and drop 1.8V. At (3.3V - 1.8) =  1.5; this means you should be using at least a (1.5/0.006) = 250 or 270 ohm resister for only 6mA. This may not result in a very brightly illuminated LED.

Here are a couple of hookup pics:



JTAG connections for ESP32





JTAG connections to Segger J-Link for ESP32



For information on VSCode debugging of ESP32, see this post.

My success tweet: https://twitter.com/gojimmypi/status/842861378801086464

Visual Studio 2017 source code for ESP32 JTAG Tutorial:

https://github.com/gojimmypi/ESP32/tree/master/ESP32-JTAG-VisualGDB

As a bonus, the tutorial is based on freeRTOS (I think all of the ESP32 code is using that). There's a pretty good UDemy FreeRTOS class that I'm taking:

https://www.udemy.com/mastering-rtos-hands-on-with-freertos-arduino-and-stm32fx/

Where to buy:

https://www.amazon.com/dp/B01N0SB08Q

https://www.adafruit.com/product/3269

https://www.olimex.com/Products/IoT/ESP32-CoreBoard/

See also: http://esp32.net/  (this site is so comprehensive, I should say "start here first!")

VisualGDB vgagent.exe went missing - Norton thinks it is a virus

This morning my VisualGDB starting giving me problems with weird error messages about a missing file called vgagent.exe

Rather than fuss with it, I decided might as well re-install - as I noticed there was an incrementally newer version available. So I downloaded VisualGDB-5.2r8-trial.msi (the previous one I downloaded was VisualGDB-5.2r7-trial.msi from January) from the Sysprogs VisualGDB download page.

All installed successfully and I was able to resume my attempts at getting my Segger JTAG to debug the ESP8266 (which I did!)

After taking a break for a few hours, when I returned Norton Anti-virus had popped an alert that it had detected Heur.AdvML.B 

and this screen snip of the prior removal of the same-name file just yesterday:

googling Heur.AdvML.B and there appears to be many suspect bait-and-infect links (so be careful when clicking).

There's also a thread on the Norton forum that questions whether these are false positives:

https://community.norton.com/en/forums/heuradvmlb-detected-false-positive-or-not

I've posted this question on the syslogs forum (hopefully it is indeed simply a false positive).