How debug when using NUCLEO-L476RG with X-NUCLEO-LPM01A using a debug probe?

Clark Sann · ‎2021-01-09

I after removing the SB's and jumpers I have attached the NUCLEO board to the LP01A. Of course, this completely detached the STLINK embedded on the Nucleo board. I would like to continue debugging while on the board. I see the SWD signals are on CN7/13 and 15.

If I purchased a STLink debug probe, either STLINK V2 or V3, how would I connect it to the board?

Which version is better?

How many leads do I need to hook up?

I have done a lot of development with the STM boards but I have always used the embedded STLINK and have never used a debug probe.

I am pretty sure that to get accurate power measurements I would need to remove the debug probe after downloading the firmware. Right?

KnarfB · ‎2021-01-10

Hi Clark,

disclaimer: I don't have a X-NUCLEO-LPM01A, sorry. But, a minimal connection for debugging are just SWCLK, SWDIO and GND. So it should be possible to use the on-board SWD link by closing the jumpers (and prepare the SBs for measurment as you did). This works even if you have physically detached the ST-LINK (which I have done with a Nucleo F401-RE board) and connect the 3 wires.

The only debug features you are loosing are hardware reset (SB12 NRST is open) and SWO debug print output (SB15 SWO is open), virtual COM Port which are not strictly needed.

If you (still) want to buy a probe: anything will do. V3 is newer and potentially faster (USB 2.0 full speed), differences are listed here

Overview of ST-LINK derivatives - STMicroelectronics

If you use more than one USB (ST-LINK + board power supply) be careful that they all share the same GND, i.e. USB ports from the same PC/laptop.

hth

KnarfB

Clark Sann · ‎2021-01-10

Thank you for your detailed answer.

Clark Sann · ‎2021-01-26

I have removed all the jumpers and solder bridges to effectively disconnect the STLink from my board. I have not physically separated the STLink from the MCU board. I have then connected the 3 wires for SWCLK, SWDIO, and GND. I cannot get it to work. I find if I hold the reset button down it gets further along the path to connect but it still doesn't finish. I have found that I also need to connect 3V3 to the STLink, otherwise the debug printout shows 0V. And because I have to hold the reset button down, it appears to me that I also need NRST hooked up, but as far as I can tell the NRST pin is not brought out to the pins on the Nucleo board. ARGGG!

Out of desperation I have also purchased a V3Set. That has helped. With it I have connected SWCLK, SWDIO, Vcc, and GND. If I hold the reset button at the time I establish STlink connection, I can get it to connect and program the board, but only if I use STProgrammer. I cannot get it to work with STMCubeIDE.

I've been working on this for 48 hours and this is the best I can do so far.

Can someone tell me how to connect up either the STLink V3Set or the attached STLink to the board (with the relevant jumpers removed so it does not draw any power)

and get it to work so I do not have to hold the reset button down and so I can use CubeIDE?

Kraal · ‎2021-01-27

Hi,

Regarding the NRST pin, it is brought out to the Arduino connector CN6 pin 3 and to the Morpho connector CN7 pin 14.

Best regards.

Clark Sann · ‎2021-01-27

Thank you. I have found when I use SWCLK, SWDIO, NRST, and GND, everything works great. I’ve read that adding Vdd will help the programmer also.

KnarfB · ‎2021-01-27

> I’ve read that adding Vdd will help the programmer also.

Some probes want Vdd input from the target to detect the target and adjust voltages. Other probes (mainly cheap clones) *supply* Vdd to the target. Be careful when connecting.