Here’s the pinout for the PMA Connector and the Pogo Pins. You may hear us sometimes call it the Modular Connector. This is Modular Connector is doing a lot of work and has a whole host of connections running through it. Just follow the key and you should be okay. The Plug is mounted inside the pi-top  but all our plates use the receptacle.
It’s a 100 pin connector (50x2) with a 0.80 mm pitch. The manufacturer is Amphenol and the recpt part number is 10144517-10XXXXXX while the plug part number is 10144518-10XXXXXX.
We recommend downloading the image so you can see all the definitions!
|Name||Function||Voltage (Volts)||Max Current (Amps)||Descriptions|
|VSYS_OUT||Power Out||6.4 - 8, 12, 15||3||Outputs System Voltage. If using Battery power then 6.4 - 8.4Volts. If using USB-C Power 12 or 15 Volts. Max output is 3A. Fuse protected|
|MPWR_IN||Power In||9 - 14||3||Input to System Voltage. Lower priority to USB-C PSU. Higher priority to battery power. Can be used to charge battery pack. Fuse Protected|
|5V_USB||Power Out||5||0.6||Direct from Raspberry Pi USB Port|
|5V_PRST||Power Out||5||0.75||Available when device is powered off. Turns off when battery power dips below 5%. Fuse protected|
|5V||Power Out||5||3.5||Shares same source as 5V from 40pin connector and pogo pins but separate to 5V supplied to Raspberry Pi. Fuse protected|
|3V3_PRST||Power Out||3.3||0.15||Available when device is powered off. Turns off when battery power dips below 5%. Fuse Protected|
|3V3||Power Out||3.3||1.5||Shares same source as 3V3 from 40pin connector. Fuse protected|
|GPIO_XX||I/O||GPIOs tied directly to Raspberry Pi. ESD Protected. Direct connection between the 40pin connector and the PMA Connector|
|MCU_RESET||Input||External Reset to pi-topHub MCU. (Connect to GND to reset)|
|MCU_SWDIO||I/O||MCU Serial Wire Data Input/Output|
|MCU_SWCLK||I/O||MCU Serial Data Clock|
|PWR_SW||Input||Tied to device power switch. High to turn on. Logic High @ 2.2V|
|USB_DX||Data||USB data pair from USB-Hub Controller on pi-top Hub|
|DSI_XX||Data||Display Serial Interface from Raspberry Pi|
|CSI_XX||Data||Camera Serial Interface from Raspberry Pi|
|MIPI_SXX||I2C||MIPI I2C from Camera/Display Serial Interface from Raspberry Pi|
All pins marked N/C are not electrically connected.