The MPLAB ICE 4 using the ICE 4 JTAG Adapter Board provides a legacy 10-pin 50-mil JTAG connection as well as a legacy 20-pin 100-mil JTAG connection.
Direct Connection to a 10-pin 50-mil Header
Use the 10-pin 50-mil flat cable to connect directly to a target board with headers complying with the Arm® Cortex® Debug header pinout shown in SAM JTAG Pinout (Cortex-M debug connector).
Direct Connection to a 20-pin 100-mil Header
Plug the adapter board into targets with a 20-pin 100-mil header.