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Fatal error-NO MCU found?

rj
Associate II
Posted on February 11, 2012 at 21:44

Last night I was working with my STM32L and everything was working properly. I had loaded some code to flash the leds. I had the board set up on a bread board and was using the the external 3v power supply pins to power a separate circuit.

After about an hour working with the circuit, I went to go back and load some code onto the board, but now  I am coming up with  this when I try to download and debug: ''Fatal error: No MCU found''. I am a little bit bewildered as to why this is happening. I checked the the ST-link drivers and re installed them to no avail. Did I  fry the board with too much amperage going into the external 3v? My circuit is using approx. 12mA. I checked the voltage off the 3v pin and its still reading fine.

I  happen to own a new board, so I plugged that into my pc alone without  the external circuit I was building... and it worked fine, was able to download my code onto the board

Any suggestions on what is happening here or how to fix this if it is fixable would be greatly appreciated..

Thanks,

Ray

5 REPLIES 5
flyer31
Senior
Posted on February 12, 2012 at 01:57

What development system are you using?

With the Keil system at the beginning often I got the error message ''Invalid ROM table''. This happens, if you try to load a program, which in the startup configures the PLL frequency to a too high value. The ST4 Discovey board has 8MHz crystal, and the Keil MBCSTM32F400 board has a 25MHz crystal. If you load a ST4 Discovery example to the Keil board, you have to be very careful, that in the startup code the variables are correctly redefined, otherwise exactly this will happen (the Discovery examples usually use PLL frequency of 168MHz, so then with the Keil 25MHz the PLL would try to got to about 600MHz - which is a bit much).

Unfortunately Debugger of STM32 seems to have no possibility to startup in some ''safe mode'' (although the devices have internal RC osciallator, I think ST should maybe think of implementing this in future devices, would be very helpful).

In such a case you need to do the following things at the Keil board: Power down, set Jumper BOOT0, re-power, set Flash load settings to ''Erase complete device'' and load down some working Keil example. Then again power down, reset BOOT0 jumper, and re-power - then it will work again.

rj
Associate II
Posted on February 12, 2012 at 07:27

Hi Bill,

I am using IAR Embedded Workbench IDE. Unfortunately I'm not familiar with Keil.

You mention resetting the BOOT0 Jumper, how do you do this?

Posted on February 12, 2012 at 07:49

You get the BOOT0 pin on the chip high.

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rj
Associate II
Posted on February 12, 2012 at 20:44

Thanks clive1 for the response.

Forgive me if I ask something obvious, Im new to microcontroller world 🙂

I happen to have a new STM32l board and loaded the exact same code on it and the board performed as it should, leading me to believe the problem isnt with my code. Also I dont think I fried my board because I checked some voltage levels across the pins and am getting the correct reading...power is still getting to the unit.

I did read through Greg73's forum post and he mentions removing the small resistor and  then soldering the SB3 bridge. I was wondering if there was another way to reset  the BOOT0 Jumper other than the soldering technique?

Posted on February 13, 2012 at 04:18

Well you really need to remove the SB3 solder bridge, but I guess you could short it to VCC, or pull it to VCC with a 33 or 47 ohm,  but that frankly doesn't sound any easier than just reflowing and wicking off the solder/zero-ohm

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