JLink is not able to detect STM32L476

Posted on August 26, 2015 at 17:10

Hi horaira, 

Please try to connect under Reset.

-Syrine-

Posted on August 26, 2015 at 18:59

Is it known issue or we are doing something wrong ?

Well in some sense, you're removing all power from the chip and expecting it to function normally. Connecting via SWD/JTAG takes some time, one technique is to hold the device in reset while connecting, another is to put the device in System Loader mode to stop your code running. Finally there are DBGMCU settings you can use to keep the connection alive, review the documentation for specifics.

Posted on September 23, 2015 at 18:05

Thanks cliv1,

Problem is that we are not able to flash using j-Link Commander

jlink.exe -device ......

as mentioned by you , when we are trying to hold reset and then flash its happening.

But we don't want this behavior as in automation build environment no one will be there to hold reset button, I am surprised that why JLink is not using reset pin to reset and halt the device ?

Something like

with Pre–reset — applies a hardware reset(HW RESET) before connecting to the device.

under Reset — holds the hardware reset(HW RESET) signal active while connecting to the device. You may use this option when the user program mistakenly disables the JTAG/SW interface. 

Posted on September 23, 2015 at 18:44

Do you have NRST connected on the interface?

You'll have to discuss the J-Link functionality with Segger.

You could also consider other programming alternatives, and test fixturing.

Posted on September 24, 2015 at 16:14

Yes, the nRST is connected on Interface

We are using J-Link LITE CortexM

Connected Pins are

VMCU

SWDIO

SWCLK

SWO

nRESET

We are stuck,

In UM08001 , It seems there is option for STM32 Devices specially to overcome this situation but I don't know how to use it

5.8.2.4 Type 3: Connect under Reset

J-Link connects to the target while keeping Reset active (reset is pulled low and

remains low while connecting to the target). This is the recommended reset strategy

for STM32 devices. This reset strategy has been designed for the case that communication with the core is not possible in normal mode so the VC_CORERESET bit can not be set in order to guarantee that the core is halted immediately after reset.

Posted on September 29, 2015 at 11:58

Dear Clive1,

I posted this in SEGGER forum http://forum.segger.com/index.php?page=Thread&postID=8830#post8830

 This is only with STM32L476 or Other Series also have similar behaviour, If yes, How it is being managed ?

If we are using ST-Link then this misbehavior is not seen

Thanks in advance.