Jumper JP19 disables the J-Link-OB-ATSAM3U4C JTAG functionality. When the jumper is installed, it grounds pin PA26 of the SAM3U4C that is normally pulled high. A quad analog switch (U31) is used to select the JTAG interface.
Jumper JP19 disables only the J-Link functionality. The debug serial com port that is emulated through a Communication Device Class (CDC) of the same USB connector remains operational (if JP20 is open).
LED LD6 | State | USB Cable Connected |
---|---|---|
RED | Off | J-Link not programmed or JP19 and JP20 installed |
GREEN | Off | J-Link not programmed or JP19 and JP20 installed |
GREEN | Flashing | USB port not connected |
GREEN | On | J-Link-OB connected and available |