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STM32VL Discovery Board electrical failure: Output pins max. 2.5V

Question asked by rydh.marcus on Feb 24, 2012
Latest reply on Mar 8, 2012 by rydh.marcus
Hi,

I recently noticed that my STM32VL Discovery board, while powered from the USB port would only output 2.5V on any of the pins. I checked the 5V and 3.3V outputs on the board, which only delivered approx. 4.5V and just under 3V respectively. I expected that the "5V" pin would not reach a full 5V while being powered from the USB port because of the Schottky diode (LDO regulator?), but I would have expected the 3.3V regulator to be up to spec. I'm curious if others have seen this with their boards. In any case, this doesn't explain why I'm only seeing 2.5V on the output pins.

They are connected to high impedance loads at the moment (I'm trying to communicate with a 5V 16x1 LCD display by using GPIOA in open-drain mode with 10K pull ups) but even when I connect low-current external circuits, none of the pins show any more than about 2.5-2.6V regardless of push-pull or open-drain configuration. I'm at a loss as to why this is, I would have expected a component failure to disable the board entirely. Could this be a software issue? I can't imagine it's current draw related since I haven't powered anything substantial with the board. Could this be the result of accidental short circuiting between an output pin and an adjacent ground pin? Any insight into this would be helpful.

Thanks

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