Why Nucleo F746ZG showing LD5 (Over current) on when running simple LED blink code? Also controller heating is more

[Cjosh.1]

Hello i am using Nucleo F746ZG board. When i run simple LED blink code with below code its not showing LD5 (Over current) on.

#include "mbed.h"
 
// Blinking rate in milliseconds
#define BLINKING_RATE 500ms
int main() {
  // Initialise the digital pin LED1 as an output
  DigitalOut led(LED1); // Green Color
  while (true) {
    led = !led;
    ThisThread::sleep_for(BLINKING_RATE);
  }
}

But when i changed code given below LD5(Over Current) blinking. and also controller heating is too much.

#include "mbed.h"
 
// Blinking rate in milliseconds
#define BLINKING_RATE 500ms
int main() {
  // Initialise the digital pin LED1 as an output
  DigitalOut led(LED1); // Green Color
  while (true) {
    led = !led;
  }
}

Reason behind checking this code is my main code was showing Over current LED ON, so i changed code to LED Blink, and found this issue. Looks like Nucleo board having issue for continuous operation. I have Connected SD card Module with SDMMC CN8 , when i remove SD card module from SDMMC its not showing over current.Can someone please help?

[KnarfB]

No, Nucleo boards dot get overloaded by a blinky program. If you see the correct LED blinking, check the connection with " SD card Module with SDMMC CN8" (not sure what this is) or show the relevant schematics.

hth

KnarfB

[Cjosh.1]

Hello @KnarfB​ Thanks for looking onto this thread.

Yes you are right. simple LED blink code with SD card interface with the board not creating this issue. I have asked detailed question with my schematic from which i am facing overcurrent and overheating issue. Please check this thread(https://community.st.com/s/question/0D53W00000e04i8SAA/nucleo-overcurrent-and-overheating-issue). Thank you

[KnarfB]

Yes, I have seen your new post. Nucleo power supply via VIN+GND is, in general, not a problem.

There are only 2 more pins connected, so you can find out what happens by doing some U/I measurements at those external connections.

Quick notes: the relay should not disconnect cartridge GND. When GND open, the cartridge VPH is still connected and this mighht do bad things via FIRE1.

The relay should perhaps be driven by a proper driver, including a freewheel diode, not a logic level converter.

Don't know the specs of the relay and the cartridge though, so I may be wrong.

hth

KnarfB

[Cjosh.1]

Hy @KnarfB​ I can give specification details about relay and cartridge if it helps to identify my issue. below are the details

Relay: I am using relay similar to this(https://components101.com/switches/5v-single-channel-relay-module-pinout-features-applications-working-datasheet). And relay board already having freewheel diode. Image attached 

Cartridge: Cartridge typical supply voltage is 11v. Image attached 

[KnarfB]

Okay, the relay seems haveing its driver included. My other remarks still apply.

hth

KnarfB

[Cjosh.1]

Yes @KnarfB​ thank you. we are still trying to find issue for over current and over heating, because duration is so short that we are not able to analyse issue, nucleo board controller just over heated in short period of time and not giving much time to analysis. So looking for help.

[KnarfB]

I would start measuring when the Nucleo board is not plugged.

What is the voltage at FIRE1 pin when the relay is open?

If everything is safe, connect one GPIO pin, then the other.

And so on...

[Cjosh.1]

When there is no supply via relay then all cartridge pins are at 0v including FIRE1 that we have measured. We have also interfaced transistors in between controller GPIO and cartridge to prevent this issue.

There are not only two pins connected to controller controller. about 10 pins connected to cartridge from controller (similar way showing in schematic). And all these pins are depended on each other. Now thinking to use opto-isolators to prevent board.

[Cjosh.1]

Hello @KnarfB​ Just quick question, What is the maximum output current sum of all I/O and control pins of Nucleo F746ZG board?

In stm32-F746ZG datasheet Table 15. Current characteristics mentioned rating is 120 mA. So in nucleo board sum of GPIO and control pins current have max current rating of 120 mA? that may create issue.