Use 10milisecond slotduration for openmote-cc2538 by default.
#define PORT_PIN_RADIO_RESET_LOW() // nothing
//===== IEEE802154E timing
+
+#define SLOTDURATION_10MS // by default, we use 10ms time slot
+
#ifdef SLOTDURATION_10MS
// time-slot related
#define PORT_TsSlotDuration 328 // counter counts one extra count, see datasheet
