STM32F746ZG JTAG Connection Failed

[brianrooz]

Hello,

I have two Nucleo-STM32F746ZG development boards daisy-chained together via their JTAG pins (refer to below diagram). When connecting a JLink Plus debug probe to the microcontrollers and attempting to debug the second development board in the daisy chain (Device #1), the connection fails and times out; I am only able to debug the first development board (Device #0) since JTAG assumes a single device to be connected by default, if not configured otherwise. Furthermore, when attempting to run the JLink Commander software, I cannot connect to either development board. I am using Visual Studio as my IDE/debug interface.

I've tried:

• Adaptive clocking
• Slowing down the clock speed (from 4000 kHz down to 100 kHz)
• Running "-jtagconf 4, 1" in the JLink Commander software to program/debug Device #1. The programs responds with "Cannot connect to target".
• Setting "-jtagconf 4, 1" in my launch.json file for Visual Studio to program/debug Device #1. This yields a connection timeout.
• Setting "-jtagconf 0, 0" in my launch.json file for Visual Studio to program/debug Device #0. This also yields a connection timeout.
• Deleting the "-jtagconf" setting in my launch.json file. This allows me to program/debug Device #0.

Connection Diagram:

 

Can the development boards be programmed/debugged while in a daisy-chain configuration? Is there something wrong with my hardware connections?

EDIT 1:

In the JLink Commander software, I specified my devices as "ARM7" cores instead of "STM32F746ZG" microcontrollers, and got a bit further. Connecting to the hardware now shows that four devices are found: two CoreSight JTAG-DPs (IRLen: 4) and two Unknown Devices (boundary scans, IRLen: 5). But the error I am now getting is "Error: CPU-TAP not found in JTAG Chain". Any idea what is missing from my configuration?

Reference picture:

EDIT 2:

I've played with a few more settings within the JFlash software, and have verified that my hardware setup is correct. I believe this is now a configurations issue with JFlash. I will mark this question as closed.

[Amel NASRI]

Hi @brianrooz​ ,

>> I believe this is now a configurations issue with JFlash. I will mark this question as closed.

Could you please answer your own question putting your findings (preferable to share the solution when found) and select your reply as a best answer?

This is the best way to close a question.

-Amel

[brianrooz · Accepted solution]

Hello all,

I've found that that my version of JFlash was out of date, and did not support JTAG flashing with the STM32 family of microcontrollers. JFlash version 7.60b and all newer versions will support STM32 JTAG.

Thanks again!