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Heaton.John
Heaton.John
Associate II
November 30, 2017
Solved

STM32L432 Nucleo-32 External Power

  • November 30, 2017
  • 7 replies
  • 6977 views
Posted on November 30, 2017 at 21:45

I have developed a program that runs on the STM32L432 Nucleo-32. When I write the program to the demo board using the USB everything works great. When I remove the USB cable and connect 5V/GND to the board, L2 goes red but the program doesn't run (I have the green LED flash). If I plug the USB cable in after powering up the board, the program does start to run. If I run the exact same program on my STM32476 Nucleo-64, the program runs fine (power jumper JP5 set to E5V). There is no mention of additional settings in the manual or datasheet for the STM32432. Any thoughts on this issue? What is the difference in powering the two demo boards?

    This topic has been closed for replies.
    Best answer by Tesla DeLorean
    Posted on November 30, 2017 at 22:17

    Check ST-LINK FW version, seem to recall V2J25 would hold device in reset absent USB

    7 replies

    Tesla DeLorean
    Tesla DeLoreanBest answer
    Guru
    November 30, 2017
    Posted on November 30, 2017 at 22:17

    Check ST-LINK FW version, seem to recall V2J25 would hold device in reset absent USB

    Tips, Buy me a coffee, or three.. PayPal Venmo (See Profile) Up vote any posts that you find helpful, it shows what's working..
    Heaton.John
    Heaton.JohnAuthor
    Associate II
    November 30, 2017
    Posted on November 30, 2017 at 22:41

    Thanks Clive. I did see the previous post on this issue and checked. The board firmware is V2J28 so I was assuming it wasn't a problem on this version.... I just checked the actual voltage and the NRST pin is in fact high (3V) when powered from the USB but when I externally power the board and check NRST, the voltage is only 1.4V. So something is fishy here. Do you know of a version that works for this board? 

    Tesla DeLorean
    Tesla DeLorean
    Guru
    December 1, 2017
    Posted on December 01, 2017 at 00:38

    I think the V2J28 should be fine, haven't dug through the schematic on the board

    Tips, Buy me a coffee, or three.. PayPal Venmo (See Profile) Up vote any posts that you find helpful, it shows what's working..
    Heaton.John
    Heaton.JohnAuthor
    Associate II
    December 8, 2017
    Posted on December 08, 2017 at 15:06

    Just so others may know, there is still a bug in the ST-LINK firmware (DEC 2017) that holds the NRST pin low, so the STM32 can't run. The work around until ST gets it fixed is to use a jumper wire between NRST and 3.3V pins on the header, this allows the chip will run as normal. Another workaround is to power the chip via external 3.3V, which avoids the problem entirely. Of course, then the ST-LINK won't function.

    eBirdman
    eBirdman
    Senior
    May 31, 2018
    Posted on May 31, 2018 at 04:42

    Hi John,  Are you aware if this problem has been fixed by now?

    Heaton.John
    Heaton.JohnAuthor
    Associate II
    May 31, 2018
    Posted on May 31, 2018 at 13:39

    I don't know if its fixed or not. I posted the question directly to ST and they just ignored it. I laid out a PCB myself and powered it via 3.3V, so its not a problem. Good luck

    MJean
    MJean
    Associate
    December 4, 2018

    With the jumper, even 5V or 3.3V, power consumption rise to 80mA !

    I just remove jumper SB9 (between STLINK T_NRST and STM32L432 NRST) and both standalone run or STLINK debug run correctly.

    LGrub.2
    LGrub.2
    Visitor II
    May 29, 2020

    Hello, I had the same issue i.e.

    when powering the stml432kc from the 5V pin only, the program would not start as the reset pin is low

    • st-link version: v2j36m26
    • sb9: connected

    My solution:

    • connect a 150Ohm resistor between RST and 3V3 (the outputs of the arduino nano header)
    • that way, RST is pulled high as long as the ST-LINK chip is not powered on and the program starts.
    • I tried it with 330Ohm and and 6.8k, but that did not work.

    If anybody sees any issues with that solution, I'd be happy to know about it :)

    VNava.1
    VNava.1
    Associate III
    December 9, 2021

    Hello Community! Any news regarding this issue?

    I have the same problem when I supply the NUCLEO F303K8 with +5V or +3V3. If I connect RST pin (CN4 pin3) to the +3V3 pin (CN4 pin14) I can se my project works (example: blinking LED3) but I don't know if from the hardware point of view this is a correct procedure.

    For example, regarding this issue, @MJean​ said in this post

    "With the jumper, even 5V or 3.3V, power consumption rise to 80mA !

    I just remove jumper SB9 (between STLINK T_NRST and STM32L432 NRST) and both standalone run or STLINK debug run correctly."

    Which is the correct solution?

    • A jumper between RST and 3V3 (with or without 150 Ohm resistor)
    • Removing SB9
    • Other solution

    Thank you in advance

    Vincenzo

    JMarc.5
    JMarc.5
    Associate II
    March 28, 2022

    Hello I've got the same issue when powering an F303Ze Nucleo with 5V(It works fine when the USB is connected but the code doesn't start when it's only with 5V).

    Did you find a solution?

    VNava.1
    VNava.1
    Associate III
    March 28, 2022

    Hi! I considered valid the answer given by @MJean​. He said in this post:

    "I just remove jumper SB9 (between STLINK T_NRST and STM32L432 NRST) and both standalone run or STLINK debug run correctly". Also the NUCLEO manual said:

    0693W00000Lw1b3QAB.png 

    You can consider also the possibility to put always high the value of the NRST pin connecting it with a 150 Ohm resistor, but I'm not sure about the correctness of this solution.

    FFUMI.1
    FFUMI.1
    Visitor II
    March 13, 2023

    Hi all, I know it'a bit old, but I'm facing exactly the same problem here, with a L432KC Nucleo-32 board: when powered through the +5V (CN4 pin 4), the board won't boot up. Ok, I've seen a few suggestions here, to solve this problem:

    1) close (on) SB9 jumper

    2) short NRST (CN4 pin 3) with 3V3 (CN4 pin 14)

    3) pull NRST up to 3.3V with a 150 Ohm resistor between RST and 3V3

    Solution 1 is permanent and won't allow programming the board through USB, unless physically reverting the SP9 configuration. So, I would go for 2 or 3, but I'm not sure what is the correct one. Pulling with 150 Ohm is a rather strong pull, similar to a short I'd say, so I wonder if anyone has measured the overall current drain in such a configuration, and if it will make the USB programming still possible.

    I still wonder why ST won't fix the User Manual, explaining that and providing a complete solution for an external power scheme. Is there an Errata around, by chance?

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