This is a bidirectonal open-drain signal that is connected to Zynq's PS_SRST_B PS_POR_B and can be asserted by the following devices:
* a multi-rail voltage monitor that monitors 3.3VIN power rails and all of the rails generated by Bora's PSU. This monitor
** in case of a power glitch, asserts MEM_WPn signal in order to prevent any spurious write operation on flash memories too. MEM_WPn is 3.3V, push-pull, active low.