NUCLEO-F411: need to reset the board to make the program to start

[AMAL01]

Hello,

NUCLEO-F411RE JP5 in E5V reset

When my F411RE board is powered with 5V, I have to press the reset button to start it. Why doesn't it start? Thank you for your help.

[mƎALLEm]

Hello @AMAL01 and welcome to the ST community,

Did you refer to UM1724 ? this section?:

[Ozone]

> When my F411RE board is powered with 5V, ...

What do you mean here exactly ?
Through the USB / ST-Link, or a 5V header pin ?
Check the user manual what power supply methods are allowed and what conditions apply.
Here a section from a Nucleo-32 manual of mine :

> Why doesn't it start?

How do you know it's 'started' or 'not started' ?

[AMAL01]

Hello,

I have a display I2C.

[AMAL01]

Hello,

Power supply to CN7-6 (E5V)

JP5 to E5V (left)

JP1 not connected

I do not want to connect the USB (CN1)

[Ozone]

Consider you have a problem in your code.

Such LCD displays often require several hundreds of milliseconds to ramp up their internal voltage regulators to turn the display on. You will need to wait for a respective "ready" signal from the display, or at least wait the recommended time.
Check the display datasheet, these documents usually contain a relatively detailed description of the initialisation sequence.

A MCU reset of the Nucleo resets only the F411 MCU, not the display.
But now the LCD initialalisation has finished, and the board "starts".

[AMAL01]

Hello,
I'm still certain it's a reset issue.

On my system, I have an I2C display and a serial connection (RS232).
When powered on with E5V, the display doesn't appear, and the RS232 COM port doesn't work. If I connect via USB, it works fine.

It might be a stabilization issue (3.6V) during a reset.

Regards,