Smoke came out of the MPU and when I connect it to the computer, the power light is on, but the usb device is not recognized.

[ASONA.1]

I connected the 5v input of usb-ttl to the 5v output of the MPU, while the mpu was plugged into the computer and suddenly smoke came out. Now I get 2.8V from the 5v output of the MPU, 2.5v from the 3v output. Also in the debug circuit, r4,r10,r11,r14 The ,r9 resistors are short-circuited and the d1 diode drops 2.55 volts (this is a bit weird to me).

1) Do you think the mpu can be reused?

2) I couldn't find the resistor and diode values ​​on the board from the schematic. Can I find their values?

[ASONA.1]

The MPU was plugged into the computer. The USB-TTL was also plugged into the computer. Then I connected the 5v supply input of the USB-TTL to the 5v output of the MPU. The smoke came out and I disconnected it immediately. Now when I plug the MPU into the computer, the power light is on and from the ,5v and 3v outputs. I am measuring the value. However, there is a short circuit in some diodes and resistors in the debug circuit.

[AScha.3]

so , i looked at the circuit and...if your lucky, you killed only D1 .

test:

• disconnect everything from the board;
• solder small piece of wire to D1, both sides, to bypass it.
• now connect CN1 usb to your PC.
• should see ...stlink.
• and never connect again - whatever you did connect. will kill something ...
• >the 5v input of usb-ttl < is in best case a short to gnd. do not use again !

[ASONA.1]

I will try you said but ı want to ask one more thing. There is a 2.55 voltage drop across D1 diode. Is there any change for this.

[AScha.3]

D1 is no more the diode, she or he was before....

you have to replace it . with a new D or just a bridge/bypass .

[ASONA.1]

I did what you said, LD1(ın debugger circuit) blinks when diode is short circuited.

[Piranha]

> Note: 1 Turkish lira=18.85 dollar.:)

Not in my universe. You have to understand the basics of numbers. Anyway the numeric value of the item's price in some particular currency does not express it's universal absolute value.

> The MPU was plugged into the computer.

The word microcontroller (MCU) is written everywhere, but somehow you have managed to not see it. The STM32F4 is an MCU, not MPU. And you are connecting a board to the computer, not an MCU or MPU chip directly.

>the 5v supply input of the USB-TTL to the 5v output of the MPU

This is from where the practical issues start - you have a problem of the basic input/output concepts.

> I can't buy a new microcontroller because it's too expensive here.

Nucleo boards start from 10 EUR. If you have an access to the internet, you can afford it. And Turkey is not in a middle of nowhere...

> I need to get this fixed

Without understanding things there is a high chance of damaging the board even more. You should first learn the basics of electronics, not start with repairing MCU boards.

[ASONA.1]

I was going to connect it to ground instead of 5v, what's the deal with knowing the input output concept. Second, 10 euro may be cheap for you, but not here. Third, I just asked questions, your job is not to judge.

[AScha.3]

so - your job is to judge ? -- who is the judge now ??

[ASONA.1]

I didn't tell you, thank you very very much for your help