I was working on some function to view ADC values on an LCD, and suddenly the LCD went wrong and noisy. I felt the board's pwr pin_header was hot, also, after reset the problem persisted.

I've found the ULPI USB IC USB3320 becoming extremely hot after establishing 5 V of board. Note that I was powering the board by a USB cable through the USB port related to the USB3320.

I hope everything will become OK by removing that bad IC, and I wonder why this happened?

Update: after removing the USB IC, the problem with the LCD persisted. Though I can debug the MCU and applications running, we have glitches on the LCD, including flickering, pixel freeze after being used and dead pixels. I think my device's LCD is now unusable.

Note: starting address of LTDC buffer is changing fast.

New observation: after two days I tested it again. I powered it only through the debug port. LCD performance was looking good, the weird thing was that when touching the USB IC location the LD5 (USB bus power), the LED turns on and after few seconds or more it decays off. I could view plots not badly but have a few problem with viewing static image patterns.

Then sadly I again powered it through that damn USB port and again catastrophy happened: pixel freeze, memory effect, and bad pixel pattern appearing among main views, and now this effect doesn't vanish by powering it through the debug port.

Also I've seen that LCD examples are working great on the board, so maybe my configuration must be revisited since I've changed the frequency from the 214 MHz of the examples to 150 MHz, maybe this is a problem and the hardware problem, for example power fluctuation, goes on to disaster.

  • \$\begingroup\$ are you asking someone to make a guess about the cause of failure? \$\endgroup\$
    – jsotola
    Jan 26 at 7:15
  • \$\begingroup\$ Did you have any other equipment connected to the board than your computer via USB? Anything connected to the ADC inputs for example? \$\endgroup\$
    – Klas-Kenny
    Jan 26 at 7:48
  • \$\begingroup\$ @Klas-Kenny My ADC is connected to microphone, three port of my PC, one for mouse and two for discovery board one power and one debug! \$\endgroup\$ Jan 26 at 13:40
  • \$\begingroup\$ Do you have a voltmeter? I suggest grabbing the schematic from STM’s website and probing around the board to look for anything strange. \$\endgroup\$
    – Ryan
    Jan 29 at 16:00
  • \$\begingroup\$ @Ryan Good sugg, But really how USB IC heat generation correlates? \$\endgroup\$ Jan 29 at 21:15

1 Answer 1


First RCC configuration was incorrectly configured as BYPASS instead of Crystal! and secound initializing sequence was invoked in LTDC instead of FMC.

The Discovery board is happy now althpugh it has lost his USB IC. :\


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