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STM32F4 Boot Loader and GPIO Pull-up/down settings?

Question asked by shaver.bob on Mar 24, 2014
Hi,

I cannot find this in the boot loader doc (AN2606) or on this forum.  Do we need external pull-up or pull-down resistors on unused USART or CAN Rx signals?  Or does the ROM-based boot loader (i.e. booting from system memory) enable the internal pull-up/down resistors while looking for activity on various USART/CAN/USB inputs?  In my current design we want the USB boot loader to run and the USART/CAN Rx pins would otherwise be left as no-connects and I would really rather not have to put resistors there (severe space constraints).

Thanks.

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