My board is burnt or something else?

Thread Starter

ssonel1

Joined Feb 24, 2020
15
While trying to read ADC value over voltage divider I accidentally connected not divided voltage to ADC pin. That was about 10V and with burnt smell I promptly intervene and cut the connection. The board(STM32F4 discovery) was hot but I could touch it. After that I put the ADC pin to true node of voltage divider this time. The program that already flashed, read that value and sent it over UART to computer. There was no problem until few-ten seconds. MCU stopped sending values or maybe reading ADC values. When try to flash another code to test what's wrong, I got error that saying: Flast Timeout. Reset the target and try it again. This is the error I get from keil. I tried connecting with ST-Link too and that gives error again saying: Cannot read memory! Disable Read Out Protection and retry.

Hoping that the problem is not my board is dead it is about software, I tired loading template project that HAL library gives and get same errors.

Is my board dead? or it did something to protect itself so I cannot flash anything?

I am feeling like my pet fish is dead, I hope it's just faint.
 

dl324

Joined Mar 30, 2015
10,763
While trying to read ADC value over voltage divider I accidentally connected not divided voltage to ADC pin. That was about 10V and with burnt smell I promptly intervene and cut the connection.
What was the current capability of what you connected to the ADC input?

If the current forced in to the input was high enough, you could have triggered SCR action in the device. The longer you let that condition persist, the more likely the device was damaged.
 

Thread Starter

ssonel1

Joined Feb 24, 2020
15
What was the current capability of what you connected to the ADC input?

If the current forced in to the input was high enough, you could have triggered SCR action in the device. The longer you let that condition persist, the more likely the device was damaged.
The source of 10V was six or seven series of AA alakaline battery.
 

Thread Starter

ssonel1

Joined Feb 24, 2020
15
More than enough to fry the device.

When you trigger SCR action, current flow can cause the device to melt/burn. If your device isn't completely dead, it's certainly now unreliable. Chalk it up to experience, buy a replacement, and be more careful in the future.
God rest his soul then. But I still have the body. Is there any part that I can use separately. For example can I use debugger part to program other board? I mean the burnt only affects core or all the board? My board is below:(STM32F407vg discovery)
stm.jpg
board.JPG

Thanks for all answers by the way.
 

dl324

Joined Mar 30, 2015
10,763
Is there any part that I can use separately.
Anything other than the microcontroller could still be good. It depends on what the ADC input circuitry is.

If you forward biased an input protection diode, you put more than 9V on the supply for the uC. Anything that couldn't tolerate that voltage is now also suspect.
 

mckenney

Joined Nov 10, 2018
81
For example can I use debugger part to program other board?
Under ordinary circumstances you can use the SWD header and the ST-Link jumpers to program another board. I don't know (50/50?) if your "experience" did anything to the programming chip . Try it before you rely on it.
 
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