[Figure 1, callout 23]
PS_PROG_B pushbutton switch SW3 grounds the ZU49DR RFSoC PS_PROG_B pin P32 when pressed. This action clears programmable logic configuration, which the PS software can then act on. See the Zynq UltraScale+ Device Technical Reference Manual (UG1085) for information about the Zynq UltraScale+ RFSoC configuration.