diff --git a/nimble/controller/include/controller/ble_ll_conn.h b/nimble/controller/include/controller/ble_ll_conn.h
index d7db6878a..daf7db584 100644
--- a/nimble/controller/include/controller/ble_ll_conn.h
+++ b/nimble/controller/include/controller/ble_ll_conn.h
@@ -192,8 +192,9 @@ struct hci_ext_conn_params
 {
     uint16_t scan_itvl;
     uint16_t scan_window;
-    uint16_t conn_itvl_min;
-    uint16_t conn_itvl_max;
+    uint32_t conn_itvl;
+    uint16_t conn_itvl_ticks;
+    uint8_t conn_itvl_usecs;
     uint16_t conn_latency;
     uint16_t supervision_timeout;
     uint16_t min_ce_len;
diff --git a/nimble/controller/src/ble_ll_conn.c b/nimble/controller/src/ble_ll_conn.c
index af610b50b..53303789b 100644
--- a/nimble/controller/src/ble_ll_conn.c
+++ b/nimble/controller/src/ble_ll_conn.c
@@ -1755,14 +1755,6 @@ void
 ble_ll_conn_ext_set_params(struct ble_ll_conn_sm *connsm,
                            struct hci_ext_conn_params *hcc_params, int phy)
 {
-    /* Set slave latency and supervision timeout */
-    connsm->slave_latency = hcc_params->conn_latency;
-    connsm->supervision_tmo = hcc_params->supervision_timeout;
-
-    /* XXX: for now, just make connection interval equal to max */
-    connsm->conn_itvl = hcc_params->conn_itvl_max;
-
-
     /* Check the min/max CE lengths are less than connection interval */
     if (hcc_params->min_ce_len > (connsm->conn_itvl * 2)) {
         connsm->min_ce_len = connsm->conn_itvl * 2;
@@ -1776,8 +1768,6 @@ ble_ll_conn_ext_set_params(struct ble_ll_conn_sm *connsm,
         connsm->max_ce_len = hcc_params->max_ce_len;
     }
 
-    ble_ll_conn_calc_itvl_ticks(connsm);
-
 #if (BLE_LL_BT5_PHY_SUPPORTED == 1)
     ble_ll_conn_init_phy(connsm, phy);
 #endif
@@ -3176,6 +3166,7 @@ ble_ll_init_rx_isr_end(uint8_t *rxbuf, uint8_t crcok,
     struct ble_ll_resolv_entry *rl;
 #endif
 #if MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_EXT_ADV)
+    struct hci_ext_conn_params *hcp;
     struct ble_ll_scan_sm *scansm;
     uint8_t phy;
 #endif
@@ -3425,15 +3416,16 @@ ble_ll_init_rx_isr_end(uint8_t *rxbuf, uint8_t crcok,
     }
 
     if (connsm->scansm->ext_scanning) {
-            phy = ble_hdr->rxinfo.phy;
+        phy = ble_hdr->rxinfo.phy;
 
-            /* Update connection state machine with appropriate parameters for
-             * certain PHY
-             */
-            ble_ll_conn_ext_set_params(connsm,
-                                       &connsm->initial_params.params[phy - 1],
-                                       phy);
+        hcp = &connsm->initial_params.params[phy - 1];
 
+        connsm->slave_latency = hcp->conn_latency;
+        connsm->supervision_tmo = hcp->supervision_timeout;
+
+        connsm->conn_itvl = hcp->conn_itvl;
+        connsm->conn_itvl_ticks = hcp->conn_itvl_ticks;
+        connsm->conn_itvl_usecs = hcp->conn_itvl_usecs;
     }
 #endif
 
@@ -3472,6 +3464,18 @@ ble_ll_init_rx_isr_end(uint8_t *rxbuf, uint8_t crcok,
         ble_hdr->rxinfo.user_data = NULL;
         STATS_INC(ble_ll_stats, aux_conn_req_tx);
     }
+
+    if (connsm->scansm->ext_scanning) {
+        phy = ble_hdr->rxinfo.phy;
+
+        /* Update connection state machine with appropriate parameters for
+         * certain PHY
+         */
+        ble_ll_conn_ext_set_params(connsm,
+                                   &connsm->initial_params.params[phy - 1],
+                                   phy);
+
+    }
 #endif
 
     STATS_INC(ble_ll_conn_stats, conn_req_txd);
diff --git a/nimble/controller/src/ble_ll_conn_hci.c b/nimble/controller/src/ble_ll_conn_hci.c
index 9936b9d34..aa6de540b 100644
--- a/nimble/controller/src/ble_ll_conn_hci.c
+++ b/nimble/controller/src/ble_ll_conn_hci.c
@@ -556,6 +556,25 @@ ble_ll_conn_hcc_params_set_fallback(struct hci_ext_create_conn *hcc,
 #endif
 }
 
+static void
+ble_ll_conn_itvl_to_ticks(uint32_t itvl, uint16_t *itvl_ticks,
+                          uint8_t *itvl_usecs)
+{
+    uint32_t ticks;
+    uint32_t usecs;
+
+    usecs = itvl * BLE_LL_CONN_ITVL_USECS;
+    ticks = os_cputime_usecs_to_ticks(usecs);
+    usecs = usecs - os_cputime_ticks_to_usecs(ticks);
+    if (usecs == 31) {
+        usecs = 0;
+        ++ticks;
+    }
+
+    *itvl_ticks = ticks;
+    *itvl_usecs = usecs;
+}
+
 int
 ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
 {
@@ -564,6 +583,8 @@ ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
     const struct hci_ext_conn_params *fallback_params = NULL;
     struct hci_ext_create_conn hcc = { 0 };
     struct ble_ll_conn_sm *connsm;
+    uint16_t conn_itvl_min;
+    uint16_t conn_itvl_max;
     int rc;
 
     /* validate length */
@@ -629,13 +650,12 @@ ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
             return rc;
         }
 
-        hcc.params[0].conn_itvl_min = le16toh(params->conn_min_itvl);
-        hcc.params[0].conn_itvl_max = le16toh(params->conn_min_itvl);
+        conn_itvl_min = le16toh(params->conn_min_itvl);
+        conn_itvl_max = le16toh(params->conn_max_itvl);
         hcc.params[0].conn_latency = le16toh(params->conn_latency);
         hcc.params[0].supervision_timeout = le16toh(params->supervision_timeout);
 
-        rc = ble_ll_conn_hci_chk_conn_params(hcc.params[0].conn_itvl_min,
-                                             hcc.params[0].conn_itvl_max,
+        rc = ble_ll_conn_hci_chk_conn_params(conn_itvl_min, conn_itvl_max,
                                              hcc.params[0].conn_latency,
                                              hcc.params[0].supervision_timeout);
         if (rc) {
@@ -649,6 +669,10 @@ ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
             return BLE_ERR_INV_HCI_CMD_PARMS;
         }
 
+        hcc.params[0].conn_itvl = conn_itvl_max;
+        ble_ll_conn_itvl_to_ticks(conn_itvl_max, &hcc.params[0].conn_itvl_ticks,
+                                  &hcc.params[0].conn_itvl_usecs);
+
         fallback_params = &hcc.params[0];
         params++;
     }
@@ -660,13 +684,12 @@ ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
         }
         len -= sizeof(*params);
 
-        hcc.params[1].conn_itvl_min = le16toh(params->conn_min_itvl);
-        hcc.params[1].conn_itvl_max = le16toh(params->conn_min_itvl);
+        conn_itvl_min = le16toh(params->conn_min_itvl);
+        conn_itvl_max = le16toh(params->conn_max_itvl);
         hcc.params[1].conn_latency = le16toh(params->conn_latency);
         hcc.params[1].supervision_timeout = le16toh(params->supervision_timeout);
 
-        rc = ble_ll_conn_hci_chk_conn_params(hcc.params[1].conn_itvl_min,
-                                             hcc.params[1].conn_itvl_max,
+        rc = ble_ll_conn_hci_chk_conn_params(conn_itvl_min, conn_itvl_max,
                                              hcc.params[1].conn_latency,
                                              hcc.params[1].supervision_timeout);
         if (rc) {
@@ -680,6 +703,10 @@ ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
             return BLE_ERR_INV_HCI_CMD_PARMS;
         }
 
+        hcc.params[1].conn_itvl = conn_itvl_max;
+        ble_ll_conn_itvl_to_ticks(conn_itvl_max, &hcc.params[1].conn_itvl_ticks,
+                                  &hcc.params[1].conn_itvl_usecs);
+
         params++;
     }
 #endif
@@ -700,13 +727,12 @@ ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
             return rc;
         }
 
-        hcc.params[2].conn_itvl_min = le16toh(params->conn_min_itvl);
-        hcc.params[2].conn_itvl_max = le16toh(params->conn_min_itvl);
+        conn_itvl_min = le16toh(params->conn_min_itvl);
+        conn_itvl_max = le16toh(params->conn_max_itvl);
         hcc.params[2].conn_latency = le16toh(params->conn_latency);
         hcc.params[2].supervision_timeout = le16toh(params->supervision_timeout);
 
-        rc = ble_ll_conn_hci_chk_conn_params(hcc.params[2].conn_itvl_min,
-                                             hcc.params[2].conn_itvl_max,
+        rc = ble_ll_conn_hci_chk_conn_params(conn_itvl_min, conn_itvl_max,
                                              hcc.params[2].conn_latency,
                                              hcc.params[2].supervision_timeout);
         if (rc) {
@@ -720,6 +746,10 @@ ble_ll_ext_conn_create(const uint8_t *cmdbuf, uint8_t len)
             return BLE_ERR_INV_HCI_CMD_PARMS;
         }
 
+        hcc.params[2].conn_itvl = conn_itvl_max;
+        ble_ll_conn_itvl_to_ticks(conn_itvl_max, &hcc.params[2].conn_itvl_ticks,
+                                  &hcc.params[2].conn_itvl_usecs);
+
         if (!fallback_params) {
             fallback_params = &hcc.params[2];
         }