The 3 pin jumper selects the type of reset the user gets when user connector pin 14 "/RST" of the module is pulled low.
With J1 pins 1 and 2 shorted, the user pin 14 low will cause a hard reset;
with J1 pins 2 and 3 shorted, user pin 14 low causes a soft reset.
J1 with no pins shorted will not cause any type of user reset when user pin 14 is low.
Jun 13, 2019