ST-Link/V2 and ST-Link/V2-1 issue

[Fahad Mirza]

Posted on June 21, 2017 at 18:03

I have a custom board with STM32L051 on it. I am using an example from ST (I-Cube_lrwan). For some reason, once I load the firmware I cannot access the MCU anymore using ST-Link Utility and ST-Link/V2. It always throw 'Cannot connect to target'. But if I press the reset button before I press 'Connect' (in ST-Link Utility) and release the button right after I press 'Connect' , ST-Link/V2 can find my MCU.

But... when I use ST-Link/V2-1 from a Nucleo Board, it works perfectly. To me, its like ST-Link/V2-1 can reset the MCU properly where ST-Link/V2 cannot for some reason.

Can anyone suggest me what should I do if I want to use ST-Link/V2, in my case?

#st-link

[Bogdan Golab]

Posted on June 21, 2017 at 22:50

I would try to upgrade the ST-LINK firmware first. Use the build-in ST-Link capability to do it. Sometimes you will need to reconnect the usb cable to enter the programming mode.

[Olivier GALLIEN]

Posted on June 22, 2017 at 10:07

Hi

fahadmirza

‌

Do you select 'Connect under reset' mode in ST-Link Utility ?

Does you firmware enter any low power mode or change SWD GPIO settings which can explain you can't reconnect with a normal system reset ?

Olivier

[Bogdan Golab]

Posted on June 22, 2017 at 15:05

Sometimes you need to connect to the device under reset.

I am talking about upgrading the firmware on ST-LINK programmer (not the target MCU).

[Fahad Mirza]

Posted on June 22, 2017 at 18:34

Hello

Golab.Piotr

,

It has the updated FW. At least that's what ST-Link is showing me (FW ver: V2.JS7 STM32+STM8 Debugger). Nucleo ST-Link FW version is V2.JM17 STM32 Debug+Mass storage

Hi

GALLIEN.Olivier

‌,

Yes, the HW goes to low power mode (STOP mode) and change the SWDIO and SWCLK pins to analog. I did get the warning on ST-Link Utility ('Device is disconnected') right after I flash FW. For a long period of time I thought this was the problem and that's why I was using the external RESET button to flash my MCU.

But... the ST-Link from Nucleo can access my MCU, with low-power and changed pin configuration. That's why I was wondering what are the differences between these two ST-Links

N.B. My Nucleo board has ST-Link/V2-1 (that's what datasheet says) and the separate programmer is ST-Link/V2. And I am using 'Connect under reset'.

[Olivier GALLIEN]

Posted on June 23, 2017 at 10:23

For a connect under reset the ST-LINK drive the NRST signal of the MCU. 

On Standalone V2 probe the CN3.15 is driven and should be connected to NRST of your MCU.

Is it the case ? 

[Fahad Mirza]

Posted on June 23, 2017 at 18:51

I am not sure which pin is CN3.15. The ST-Link I have is shown below. RST is connected with my MCU's NRST.

I hope I am not having issues because it is not made by ST. Do you think that's a possibility?

[Tesla DeLorean]

Posted on June 23, 2017 at 22:24

http://www.st.com/content/ccc/resource/technical/document/user_manual/65/e0/44/72/9e/34/41/8d/DM00026748.pdf/files/DM00026748.pdf/jcr:content/translations/en.DM00026748.pdf

 

The use of NRST you indicate should suffice.

You are likely to lose connectivity if you allow the CPU to go into a low power/sleep mode, try defining 

LOW_POWER_DISABLE

DISABLE_IRQ();

/* if an interupt has occured after __disable_irq, it is kept pending * and cortex will not enter low power anyway */ if (State == LOWPOWER) {&sharpifndef LOW_POWER_DISABLE LowPower_Handler();&sharpendif } ENABLE_IRQ();

[Olivier GALLIEN]

Posted on June 26, 2017 at 10:26

Hello

Mirza.Fahad

‌

Seems this probe is not working properly.

May I suggest you to get ST Standalone probe or keep using Nucléo STLINK/V2-1 ?

Br,

Olivier

[David SIORPAES]

Posted on June 26, 2017 at 11:55

I had very similar issues with that knock off ST-Link. As far as I can tell the RST pin is driven only when used in SWIM more (for STM8), not SWD.

I'd suggest you reflash the thing with

https://github.com/x893/CMSIS-DAP

and remap the RST signal from PB0 to PB6.