SPRUJ93 august 2023
The AM263x Control Card maps two SPI instances (SPI0,SPI1) from the AM263x SoC to the HSEC 180 pin connector. Series termination resistors are placed near the SoC for each SPI clock signal.
There is 4-channel FET Switch that routes SPI1 between the PMIC and the HSEC Connector. This FET Switch has the select line driven by SPI1_MUX_SEL of the IO Expander. Additionally, there is an external pull-down resistor on the Select line, such that the PMIC routing for the SPI signals is in the default state.