The OM13526UL is the PCAL6524 24-bit GPIO evaluation board, which allows bidirectional voltage-level translation and GPIO expansion between 0.8 V to 3.6 V on SCL/SDA and 1.8 V, 2.5 V, 3.3 V, 5.5 V on I/O Ports with active low reset input control and open-drain active low interrupt output indicator (red LED) plus one hardware address input setting to select one of four different follower address. A graphical interface allows the user to easily explore the different functions of the I/O expander.