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Alchitry Io Switches with Au - Printable Version

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Alchitry Io Switches with Au - garthberry - 02-22-2019

After trying to get the switches (DIP and pushbutton) Alchitry Io working for a little too long it finally occurred to me that pulldowns need to be enabled for each of the pins attached to a switch. If pulldowns are not enabled the pin will typically float high. The pulldown resistor can be enabled on a pin by pin basis in the  constraints file as follows:

set_property PACKAGE_PIN C4 [get_ports {dip_sw[0]}]
set_property IOSTANDARD LVCMOS33 [get_ports {dip_sw[0]}]
set_property PULLDOWN TRUE [get_ports {dip_sw[0]}]