Answer

For the pre-built NCP images we include in EmberZNet releases for EFR32MG1P132F256GM48 and EFR32MG1P232F256GM48 variants (included in our Mighty Gecko Wireless SoC Starter Kit):

NCP-UART:

• PA0 – TXD
• PA1 – RXD 
• PA2 – CTS
• PA3 – RTS 

NCP-SPI:

• PC6 – MOSI 
• PC7 – MISO 
• PC8 – SCLK
• PC9 – nCS
• PD10 – nHOST_INT
• PD11 – nWAKE

To access these signals on the WSTK board, connect the external host to the Expansion Header pins according to the table "Expansion Header Pinout" in UG151.