There are 4 GPOs on the serializer and 4 GPIOs on the deserializer when the DS90UB933/934 chipsets are run off the pixel clock from the imager as the reference clock source. The GPOs on the serializer can be configured as outputs for the input signals that are fed into the deserializer GPIOs. In addition, the GPOs on the serializer can behave as outputs of the local register on the serializer. The GPIOs on the deserializer can be configured to be the input signals feeding the GPOs (configured as outputs) on the serializer. In addition the GPIOs on the deserializer can be configured to behave as outputs of the local register on the deserializer. The DS90UB933-Q1 serializer GPOs cannot be configured as inputs for remote communication with deserializer. If the DS90UB933/934 chipsets are run off the external oscillator source as the reference clock, then GPO3 on the serializer is automatically configured to be the input for the external clock and GPO2 is configured to be the output of the divide-by-2 clock which is fed into the imager as its reference clock. In this case, the GPIO2 and GPIO3 on the deserializer can only behave as outputs of the local register on the deserializer. The GPIO maximum switching rate is up to 66 kHz when configured for communication between deserializer GPIO to serializer GPO.