STK1002/NEXUS connector
From AVRFreaks Wiki
The Nexus connector connects high end emulators to STK1002. The Nexus interface extends the JTAG interface and can therefore also program the external flash in the same manner as JTAG emulators can.
The NEXUS connector mating polarized, ie. there is only one way to connect it.
Pin out
The NEXUS debug interface from AP7000 is available on an Mictor-38 connector. The Mictor-38 is a matched impedance high speed connector that supports the high frequencies involved in this debug interface and gives good mechanical stability.
For an explanation of the signals please refer the AP7000 data sheet.