SNLA308A April 2019 – October 2020 DS90UB941AS-Q1 , DS90UH941AS-Q1
Each GPIO or DGPIO may be configured for either forward or reverse direction. For the GPIO to operate correctly, both the serializer and deserializer must be configured for the proper operation. Configuration of the GPIO and DGPIO is described in the register documentation for each device. See descriptions of the GPIO Configuration registers. Note that in back channel, high-speed GPIO modes, only certain DGPIO pins are available for options that only send one or two GPIO signals in the back channel.
In splitter mode, GPIO signals go over DS90Ux941AS-Q1 FPD3 TX Port 0 and D_GPIO signals over DS90Ux941AS-Q1 FPD3 TX Port 1. Figure 11-1 shows a possible setup.