The FPC402 has two general-purpose outputs per port which can be used to drive the low-speed inputs to the module. The host controller can change the state of these outputs for each port individually, for all ports connected to a given FPC402 device simultaneously, or for all ports in the system simultaneously.

There are two configuration registers for these outputs. One register configures the enable state of the OUT_A and OUT_B pins for every port, and by default both OUT_A and OUT_B pins are disabled (tri-stated). The second register controls the output value for all OUT_A and OUT_B pins, where OUT_A has default value of 1 and OUT_B has a default value of 0. The output values must be configured before the outputs are enabled. If a default value is desired during boot up before these pins are enabled, a 10-kΩ pullup or pulldown resistor is recommended (note that SFP and QSFP modules have internal pullup and pulldowns on certain inputs). Note that if the VDD1 rail does not have power and there is an externally powered pullup resistor connected to an output pin, the output pin will be pulled low until VDD1 is supplied.

Table 8-1 provides an example signal connection. OUT_A and OUT_B are not restricted to this port pin assignment, and they can be used to drive any 3.3-V signal required for the application, provided the I_OH and I_OL limits are met.