diff --git a/apps/bttester/src/btp_gap.c b/apps/bttester/src/btp_gap.c
index 8056eaf13..715ff4473 100644
--- a/apps/bttester/src/btp_gap.c
+++ b/apps/bttester/src/btp_gap.c
@@ -909,7 +909,7 @@ auth_passkey_display(uint16_t conn_handle, unsigned int passkey)
         return;
     }
 
-    rc = ble_hs_hci_rand(&pk.passkey, sizeof(pk.passkey));
+    rc = ble_hs_hci_util_rand(&pk.passkey, sizeof(pk.passkey));
     assert(rc == 0);
     /* Max value is 999999 */
     pk.passkey %= 1000000;
diff --git a/apps/bttester/src/btp_gatt.c b/apps/bttester/src/btp_gatt.c
index 1c6320510..863d06acc 100644
--- a/apps/bttester/src/btp_gatt.c
+++ b/apps/bttester/src/btp_gatt.c
@@ -665,7 +665,7 @@ discover_destroy(void)
 }
 
 static void
-read_destroy()
+read_destroy(void)
 {
     gatt_buf_clear();
 }
diff --git a/nimble/host/include/host/ble_hs_hci.h b/nimble/host/include/host/ble_hs_hci.h
index 237712080..5b28d9991 100644
--- a/nimble/host/include/host/ble_hs_hci.h
+++ b/nimble/host/include/host/ble_hs_hci.h
@@ -100,7 +100,7 @@ int ble_hs_hci_set_chan_class(const uint8_t *chan_map);
  *                              A BLE host core return code on unexpected
  *                                  error.
  */
-int ble_hs_hci_rand(void *dst, int len);
+int ble_hs_hci_util_rand(void *dst, int len);
 
 #if MYNEWT_VAL(BLE_HCI_VS)
 /**
diff --git a/nimble/host/mesh/include/mesh/glue.h b/nimble/host/mesh/include/mesh/glue.h
index c4d058849..66722fe99 100644
--- a/nimble/host/mesh/include/mesh/glue.h
+++ b/nimble/host/mesh/include/mesh/glue.h
@@ -438,7 +438,7 @@ int bt_le_adv_start(const struct ble_gap_adv_params *param,
                     const struct bt_data *ad, size_t ad_len,
                     const struct bt_data *sd, size_t sd_len);
 
-int bt_le_adv_stop();
+int bt_le_adv_stop(void);
 
 struct k_work_delayable {
     struct ble_npl_callout work;
diff --git a/nimble/host/mesh/src/adv_legacy.c b/nimble/host/mesh/src/adv_legacy.c
index 26865058e..ec45e808b 100644
--- a/nimble/host/mesh/src/adv_legacy.c
+++ b/nimble/host/mesh/src/adv_legacy.c
@@ -18,6 +18,14 @@
 #include "mesh/glue.h"
 #include "pb_gatt_srv.h"
 
+#ifndef min
+#define min(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+#ifndef max
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#endif
+
 #if MYNEWT_VAL(BLE_MESH_ADV_LEGACY)
 /* Convert from ms to 0.625ms units */
 #define ADV_SCAN_UNIT(_ms) ((_ms) * 8 / 5)
diff --git a/nimble/host/mesh/src/glue.c b/nimble/host/mesh/src/glue.c
index ee89ee876..5bce3d8d2 100644
--- a/nimble/host/mesh/src/glue.c
+++ b/nimble/host/mesh/src/glue.c
@@ -618,7 +618,7 @@ int
 bt_rand(void *buf, size_t len)
 {
     int rc;
-    rc = ble_hs_hci_rand(buf, len);
+    rc = ble_hs_hci_util_rand(buf, len);
     if (rc != 0) {
         return -1;
     }
diff --git a/nimble/host/mesh/src/prov_device.c b/nimble/host/mesh/src/prov_device.c
index e9e2d2b12..01b1eac36 100644
--- a/nimble/host/mesh/src/prov_device.c
+++ b/nimble/host/mesh/src/prov_device.c
@@ -300,6 +300,7 @@ static void prov_dh_key_gen(void)
 	uint8_t remote_pk_le[BT_PUB_KEY_LEN];
 
 	remote_pk = bt_mesh_prov_link.conf_inputs.pub_key_provisioner;
+#if !CONFIG_BT_NIMBLE_CRYPTO_STACK_MBEDTLS
 	if (MYNEWT_VAL(BLE_MESH_PROV_OOB_PUBLIC_KEY) &&
 	    atomic_test_bit(bt_mesh_prov_link.flags, OOB_PUB_KEY)) {
 		if (uECC_valid_public_key(remote_pk, &curve_secp256r1)) {
@@ -316,6 +317,7 @@ static void prov_dh_key_gen(void)
 		prov_fail(PROV_ERR_UNEXP_ERR);
 		return;
 	}
+#endif
 
 	/* Copy remote key in little-endian for bt_dh_key_gen().
 	 * X and Y halves are swapped independently. The bt_dh_key_gen()
diff --git a/nimble/host/mesh/src/proxy_srv.c b/nimble/host/mesh/src/proxy_srv.c
index 91c87e50f..00af2f849 100644
--- a/nimble/host/mesh/src/proxy_srv.c
+++ b/nimble/host/mesh/src/proxy_srv.c
@@ -27,6 +27,14 @@
 #include "proxy_msg.h"
 #include "pb_gatt_srv.h"
 
+#ifndef min
+#define min(a, b) ((a) < (b) ? (a) : (b))
+#endif
+
+#ifndef max
+#define max(a, b) ((a) > (b) ? (a) : (b))
+#endif
+
 #if defined(CONFIG_BT_MESH_PROXY_USE_DEVICE_NAME)
 #define ADV_OPT_USE_NAME BT_LE_ADV_OPT_USE_NAME
 #else
diff --git a/nimble/host/src/ble_hs.c b/nimble/host/src/ble_hs.c
index eca53fe16..c013ad9d1 100644
--- a/nimble/host/src/ble_hs.c
+++ b/nimble/host/src/ble_hs.c
@@ -800,6 +800,11 @@ ble_hs_init(void)
     ble_hs_evq_set(nimble_port_get_dflt_eventq());
 #endif
 
+#if SOC_ESP_NIMBLE_CONTROLLER
+    /* Configure the HCI transport to communicate with a host. */
+    ble_hci_trans_cfg_hs(ble_hs_hci_rx_evt, NULL, ble_hs_rx_data, NULL);
+#endif
+
     /* Enqueue the start event to the default event queue.  Using the default
      * queue ensures the event won't run until the end of main().  This allows
      * the application to configure this package in the meantime.
@@ -853,7 +858,9 @@ ble_hs_deinit(void)
     ble_monitor_deinit();
 #endif
 
+#if SOC_ESP_NIMBLE_CONTROLLER
     ble_hci_trans_cfg_hs(NULL, NULL, NULL, NULL);
+#endif
 
     ble_npl_mutex_deinit(&ble_hs_mutex);
 
diff --git a/nimble/host/src/ble_hs_flow.c b/nimble/host/src/ble_hs_flow.c
index 8b8430dae..6cb70b861 100644
--- a/nimble/host/src/ble_hs_flow.c
+++ b/nimble/host/src/ble_hs_flow.c
@@ -40,7 +40,7 @@ static ble_npl_event_fn ble_hs_flow_event_cb;
 static struct ble_npl_event ble_hs_flow_ev;
 
 /* Connection handle associated with each mbuf in ACL pool */
-static uint16_t ble_hs_flow_mbuf_conn_handle[ MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_LL_COUNT) ];
+static uint16_t ble_hs_flow_mbuf_conn_handle[ MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_HS_COUNT) ];
 
 static inline int
 ble_hs_flow_mbuf_index(const struct os_mbuf *om)
@@ -135,7 +135,7 @@ ble_hs_flow_inc_completed_pkts(struct ble_hs_conn *conn)
     conn->bhc_completed_pkts++;
     ble_hs_flow_num_completed_pkts++;
 
-    if (ble_hs_flow_num_completed_pkts > MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_LL_COUNT)) {
+    if (ble_hs_flow_num_completed_pkts > MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_HS_COUNT)) {
         ble_hs_sched_reset(BLE_HS_ECONTROLLER);
         return;
     }
@@ -143,7 +143,7 @@ ble_hs_flow_inc_completed_pkts(struct ble_hs_conn *conn)
     /* If the number of free buffers is at or below the configured threshold,
      * send an immediate number-of-copmleted-packets event.
      */
-    num_free = MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_LL_COUNT) -
+    num_free = MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_HS_COUNT) -
                ble_hs_flow_num_completed_pkts;
     if (num_free <= MYNEWT_VAL(BLE_HS_FLOW_CTRL_THRESH)) {
         ble_npl_eventq_put(ble_hs_evq_get(), &ble_hs_flow_ev);
@@ -231,7 +231,7 @@ ble_hs_flow_startup(void)
     struct ble_hci_cb_ctlr_to_host_fc_cp enable_cmd;
     struct ble_hci_cb_host_buf_size_cp buf_size_cmd = {
             .acl_data_len = htole16(MYNEWT_VAL(BLE_TRANSPORT_ACL_SIZE)),
-            .acl_num = htole16(MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_LL_COUNT)),
+            .acl_num = htole16(MYNEWT_VAL(BLE_TRANSPORT_ACL_FROM_HS_COUNT)),
     };
     int rc;
 
@@ -265,7 +265,11 @@ ble_hs_flow_startup(void)
 
     /* Flow control successfully enabled. */
     ble_hs_flow_num_completed_pkts = 0;
+#if SOC_ESP_NIMBLE_CONTROLLER
+    ble_hci_trans_set_acl_free_cb(ble_hs_flow_acl_free, NULL);
+#else
     ble_transport_register_put_acl_from_ll_cb(ble_hs_flow_acl_free);
+#endif
     ble_npl_callout_init(&ble_hs_flow_timer, ble_hs_evq_get(),
                          ble_hs_flow_event_cb, NULL);
 #endif
diff --git a/nimble/host/src/ble_hs_hci.c b/nimble/host/src/ble_hs_hci.c
index f8a64e931..70e4bc44f 100644
--- a/nimble/host/src/ble_hs_hci.c
+++ b/nimble/host/src/ble_hs_hci.c
@@ -24,6 +24,8 @@
 #include "mem/mem.h"
 #include "ble_hs_priv.h"
 
+#include "nimble/transport.h"
+
 #define BLE_HCI_CMD_TIMEOUT_MS  2000
 
 static struct ble_npl_mutex ble_hs_hci_mutex;
diff --git a/nimble/host/src/ble_hs_hci_cmd.c b/nimble/host/src/ble_hs_hci_cmd.c
index 69fa16702..3ab9ea088 100644
--- a/nimble/host/src/ble_hs_hci_cmd.c
+++ b/nimble/host/src/ble_hs_hci_cmd.c
@@ -41,7 +41,7 @@ ble_hs_hci_cmd_transport(struct ble_hci_cmd *cmd)
 {
     int rc;
 
-    rc = ble_transport_to_ll_cmd(cmd);
+    rc = ble_transport_to_ll_cmd((uint8_t *)cmd);
     switch (rc) {
     case 0:
         return 0;
@@ -61,7 +61,7 @@ ble_hs_hci_cmd_send(uint16_t opcode, uint8_t len, const void *cmddata)
     uint8_t *buf;
     int rc;
 
-    cmd = ble_transport_alloc_cmd();
+    cmd = (struct ble_hci_cmd *)ble_transport_alloc_cmd();
     BLE_HS_DBG_ASSERT(cmd != NULL);
 
     buf = (uint8_t *)cmd;
diff --git a/nimble/host/src/ble_hs_hci_evt.c b/nimble/host/src/ble_hs_hci_evt.c
index c3147b383..c743edc60 100644
--- a/nimble/host/src/ble_hs_hci_evt.c
+++ b/nimble/host/src/ble_hs_hci_evt.c
@@ -1025,7 +1025,7 @@ ble_hs_hci_evt_process(struct ble_hci_ev *ev)
         rc = entry->cb(ev->opcode, ev->data, ev->length);
     }
 
-    ble_transport_free(ev);
+    ble_transport_free((uint8_t *)ev);
 
     return rc;
 }
diff --git a/nimble/host/src/ble_hs_hci_util.c b/nimble/host/src/ble_hs_hci_util.c
index 780325269..95108a77a 100644
--- a/nimble/host/src/ble_hs_hci_util.c
+++ b/nimble/host/src/ble_hs_hci_util.c
@@ -66,7 +66,7 @@ ble_hs_hci_util_read_adv_tx_pwr(int8_t *out_tx_pwr)
 }
 
 int
-ble_hs_hci_rand(void *dst, int len)
+ble_hs_hci_util_rand(void *dst, int len)
 {
     struct ble_hci_le_rand_rp rsp;
     uint8_t *u8ptr;
diff --git a/nimble/host/src/ble_hs_id.c b/nimble/host/src/ble_hs_id.c
index 63f750c9e..2af736f1a 100644
--- a/nimble/host/src/ble_hs_id.c
+++ b/nimble/host/src/ble_hs_id.c
@@ -54,7 +54,7 @@ ble_hs_id_gen_rnd(int nrpa, ble_addr_t *out_addr)
 
     out_addr->type = BLE_ADDR_RANDOM;
 
-    rc = ble_hs_hci_rand(out_addr->val, 6);
+    rc = ble_hs_hci_util_rand(out_addr->val, 6);
     if (rc != 0) {
         return rc;
     }
diff --git a/nimble/host/src/ble_sm.c b/nimble/host/src/ble_sm.c
index a4fcd7fd2..7c68e0f62 100644
--- a/nimble/host/src/ble_sm.c
+++ b/nimble/host/src/ble_sm.c
@@ -272,7 +272,7 @@ ble_sm_gen_pair_rand(uint8_t *pair_rand)
     }
 #endif
 
-    rc = ble_hs_hci_rand(pair_rand, 16);
+    rc = ble_hs_hci_util_rand(pair_rand, 16);
     if (rc != 0) {
         return rc;
     }
@@ -293,7 +293,7 @@ ble_sm_gen_ediv(struct ble_sm_master_id *master_id)
     }
 #endif
 
-    rc = ble_hs_hci_rand(&master_id->ediv, sizeof master_id->ediv);
+    rc = ble_hs_hci_util_rand(&master_id->ediv, sizeof master_id->ediv);
     if (rc != 0) {
         return rc;
     }
@@ -314,7 +314,7 @@ ble_sm_gen_master_id_rand(struct ble_sm_master_id *master_id)
     }
 #endif
 
-    rc = ble_hs_hci_rand(&master_id->rand_val, sizeof master_id->rand_val);
+    rc = ble_hs_hci_util_rand(&master_id->rand_val, sizeof master_id->rand_val);
     if (rc != 0) {
         return rc;
     }
@@ -336,7 +336,7 @@ ble_sm_gen_ltk(struct ble_sm_proc *proc, uint8_t *ltk)
     }
 #endif
 
-    rc = ble_hs_hci_rand(ltk, proc->key_size);
+    rc = ble_hs_hci_util_rand(ltk, proc->key_size);
     if (rc != 0) {
         return rc;
     }
@@ -361,7 +361,7 @@ ble_sm_gen_csrk(struct ble_sm_proc *proc, uint8_t *csrk)
     }
 #endif
 
-    rc = ble_hs_hci_rand(csrk, 16);
+    rc = ble_hs_hci_util_rand(csrk, 16);
     if (rc != 0) {
         return rc;
     }
diff --git a/nimble/host/src/ble_sm_alg.c b/nimble/host/src/ble_sm_alg.c
index abfa8e45b..4e9218dae 100644
--- a/nimble/host/src/ble_sm_alg.c
+++ b/nimble/host/src/ble_sm_alg.c
@@ -749,7 +749,7 @@ ble_sm_alg_rand(uint8_t *dst, unsigned int size)
         size -= num;
     }
 #else
-    if (ble_hs_hci_rand(dst, size)) {
+    if (ble_hs_hci_util_rand(dst, size)) {
         return 0;
     }
 #endif
diff --git a/nimble/host/src/ble_sm_sc.c b/nimble/host/src/ble_sm_sc.c
index ffcdc692e..50ad196a5 100644
--- a/nimble/host/src/ble_sm_sc.c
+++ b/nimble/host/src/ble_sm_sc.c
@@ -893,7 +893,7 @@ ble_sm_sc_oob_generate_data(struct ble_sm_sc_oob_data *oob_data)
         return rc;
     }
 
-    rc = ble_hs_hci_rand(oob_data->r, 16);
+    rc = ble_hs_hci_util_rand(oob_data->r, 16);
     if (rc) {
         return rc;
     }
diff --git a/nimble/transport/include/nimble/transport.h b/nimble/transport/include/nimble/transport.h
index fcb3297cf..16e99c84e 100644
--- a/nimble/transport/include/nimble/transport.h
+++ b/nimble/transport/include/nimble/transport.h
@@ -29,13 +29,309 @@ extern "C" {
 #if MYNEWT_PKG_apache_mynewt_nimble__nimble_transport_common_hci_ipc
 #include <nimble/transport/transport_ipc.h>
 #endif
+#include <inttypes.h>
+#include "os/os_mempool.h"
 
+#define BLE_HCI_TRANS_CMD_SZ        260
+/*** Type of buffers for holding commands and events. */
+/**
+ * Controller-to-host event buffers.  Events have one of two priorities:
+ * o Low-priority   (BLE_HCI_TRANS_BUF_EVT_LO)
+ * o High-priority  (BLE_HCI_TRANS_BUF_EVT_HI)
+ *
+ * Low-priority event buffers are only used for advertising reports.  If there
+ * are no free low-priority event buffers, then an incoming advertising report
+ * will get dropped.
+ *
+ * High-priority event buffers are for everything except advertising reports.
+ * If there are no free high-priority event buffers, a request to allocate one
+ * will try to allocate a low-priority buffer instead.
+ *
+ * If you want all events to be given equal treatment, then you should allocate
+ * low-priority events only.
+ *
+ * Event priorities solve the problem of critical events getting dropped due to
+ * a flood of advertising reports.  This solution is likely temporary: when
+ * HCI flow control is added, event priorities may become obsolete.
+ *
+ * Not all transports distinguish between low and high priority events.  If the
+ * transport does not have separate settings for low and high buffer counts,
+ * then it treats all events with equal priority.
+ */
+#define BLE_HCI_TRANS_BUF_EVT_LO    1
+#define BLE_HCI_TRANS_BUF_EVT_HI    2
+
+/* Host-to-controller command. */
+#define BLE_HCI_TRANS_BUF_CMD       3
+
+/** Callback function types; executed when HCI packets are received. */
+typedef int ble_hci_trans_rx_cmd_fn(uint8_t *cmd, void *arg);
+typedef int ble_hci_trans_rx_acl_fn(struct os_mbuf *om, void *arg);
+
+#if SOC_ESP_NIMBLE_CONTROLLER
+#define ble_transport_alloc_cmd() ble_hci_trans_buf_alloc(BLE_HCI_TRANS_BUF_CMD)
+#define ble_transport_alloc_event(X) ble_hci_trans_buf_alloc(X ? BLE_HCI_TRANS_BUF_EVT_LO : BLE_HCI_TRANS_BUF_EVT_HI)
+#define ble_transport_free ble_hci_trans_buf_free
+
+struct ble_hci_trans_funcs_t {
+    int(*_ble_hci_trans_hs_acl_tx)(struct os_mbuf *om);
+    int(*_ble_hci_trans_hs_cmd_tx)(uint8_t *cmd);
+    int(*_ble_hci_trans_ll_acl_tx)(struct os_mbuf *om);
+    int(*_ble_hci_trans_ll_evt_tx)(uint8_t *hci_ev);
+    int(*_ble_hci_trans_reset)(void);
+    int(*_ble_hci_trans_set_acl_free_cb)(os_mempool_put_fn *cb,void *arg);
+};
+
+extern struct ble_hci_trans_funcs_t *ble_hci_trans_funcs_ptr;
+
+/**
+ * Sends an HCI event from the controller to the host.
+ *
+ * @param cmd                   The HCI event to send.  This buffer must be
+ *                                  allocated via ble_hci_trans_buf_alloc().
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+extern int r_ble_hci_trans_ll_evt_tx(uint8_t *hci_ev);
+#define ble_hci_trans_ll_evt_tx ble_hci_trans_funcs_ptr->_ble_hci_trans_ll_evt_tx
+
+/**
+ * Sends ACL data from controller to host.
+ *
+ * @param om                    The ACL data packet to send.
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+extern int r_ble_hci_trans_ll_acl_tx(struct os_mbuf *om);
+#define ble_hci_trans_ll_acl_tx ble_hci_trans_funcs_ptr->_ble_hci_trans_ll_acl_tx
+
+/**
+ * Sends an HCI command from the host to the controller.
+ *
+ * @param cmd                   The HCI command to send.  This buffer must be
+ *                                  allocated via ble_hci_trans_buf_alloc().
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+extern int r_ble_hci_trans_hs_cmd_tx(uint8_t *cmd);
+#define ble_hci_trans_hs_cmd_tx ble_hci_trans_funcs_ptr->_ble_hci_trans_hs_cmd_tx
+
+/**
+ * Sends ACL data from host to controller.
+ *
+ * @param om                    The ACL data packet to send.
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+extern int r_ble_hci_trans_hs_acl_tx(struct os_mbuf *om);
+#define ble_hci_trans_hs_acl_tx ble_hci_trans_funcs_ptr->_ble_hci_trans_hs_acl_tx
+
+/**
+ * Allocates a flat buffer of the specified type.
+ *
+ * @param type                  The type of buffer to allocate; one of the
+ *                                  BLE_HCI_TRANS_BUF_[...] constants.
+ *
+ * @return                      The allocated buffer on success;
+ *                              NULL on buffer exhaustion.
+ */
+extern uint8_t *r_ble_hci_trans_buf_alloc(int type);
+#define ble_hci_trans_buf_alloc r_ble_hci_trans_buf_alloc
+
+/**
+ * Frees the specified flat buffer.  The buffer must have been allocated via
+ * ble_hci_trans_buf_alloc().
+ *
+ * @param buf                   The buffer to free.
+ */
+extern void r_ble_hci_trans_buf_free(uint8_t *buf);
+#define ble_hci_trans_buf_free r_ble_hci_trans_buf_free
+
+/**
+ * Configures a callback to get executed whenever an ACL data packet is freed.
+ * The function is called immediately before the free occurs.
+ *
+ * @param cb                    The callback to configure.
+ * @param arg                   An optional argument to pass to the callback.
+ *
+ * @return                      0 on success;
+ *                              BLE_ERR_UNSUPPORTED if the transport does not
+ *                                  support this operation.
+ */
+extern int r_ble_hci_trans_set_acl_free_cb(os_mempool_put_fn *cb, void *arg);
+#define ble_hci_trans_set_acl_free_cb ble_hci_trans_funcs_ptr->_ble_hci_trans_set_acl_free_cb
+
+/**
+ * Configures the HCI transport to operate with a controller.  The transport
+ * will execute specified callbacks upon receiving HCI packets from the host.
+ *
+ * @param cmd_cb                The callback to execute upon receiving an HCI
+ *                                  command.
+ * @param cmd_arg               Optional argument to pass to the command
+ *                                  callback.
+ * @param acl_cb                The callback to execute upon receiving ACL
+ *                                  data.
+ * @param acl_arg               Optional argument to pass to the ACL
+ *                                  callback.
+ */
+extern void r_ble_hci_trans_cfg_ll(ble_hci_trans_rx_cmd_fn *cmd_cb,
+                          void *cmd_arg,
+                          ble_hci_trans_rx_acl_fn *acl_cb,
+                          void *acl_arg);
+#define ble_hci_trans_cfg_ll r_ble_hci_trans_cfg_ll
+
+/**
+ * Configures the HCI transport to operate with a host.  The transport will
+ * execute specified callbacks upon receiving HCI packets from the controller.
+ *
+ * @param evt_cb                The callback to execute upon receiving an HCI
+ *                                  event.
+ * @param evt_arg               Optional argument to pass to the event
+ *                                  callback.
+ * @param acl_cb                The callback to execute upon receiving ACL
+ *                                  data.
+ * @param acl_arg               Optional argument to pass to the ACL
+ *                                  callback.
+ */
+extern void r_ble_hci_trans_cfg_hs(ble_hci_trans_rx_cmd_fn *evt_cb,
+                          void *evt_arg,
+                          ble_hci_trans_rx_acl_fn *acl_cb,
+                          void *acl_arg);
+#define ble_hci_trans_cfg_hs r_ble_hci_trans_cfg_hs
+
+/**
+ * Resets the HCI module to a clean state.  Frees all buffers and reinitializes
+ * the underlying transport.
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+extern int r_ble_hci_trans_reset(void);
+#define ble_hci_trans_reset ble_hci_trans_funcs_ptr->_ble_hci_trans_reset
+
+void esp_ble_hci_trans_init(uint8_t);
+
+#else
+/**
+ * Sends an HCI event from the controller to the host.
+ *
+ * @param cmd                   The HCI event to send.  This buffer must be
+ *                                  allocated via ble_hci_trans_buf_alloc().
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+int ble_hci_trans_ll_evt_tx(uint8_t *hci_ev);
+
+/**
+ * Sends ACL data from controller to host.
+ *
+ * @param om                    The ACL data packet to send.
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+int ble_hci_trans_ll_acl_tx(struct os_mbuf *om);
+
+/**
+ * Sends an HCI command from the host to the controller.
+ *
+ * @param cmd                   The HCI command to send.  This buffer must be
+ *                                  allocated via ble_hci_trans_buf_alloc().
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+int ble_hci_trans_hs_cmd_tx(uint8_t *cmd);
+
+/**
+ * Sends ACL data from host to controller.
+ *
+ * @param om                    The ACL data packet to send.
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+int ble_hci_trans_hs_acl_tx(struct os_mbuf *om);
+
+/**
+ * Allocates a flat buffer of the specified type.
+ *
+ * @param type                  The type of buffer to allocate; one of the
+ *                                  BLE_HCI_TRANS_BUF_[...] constants.
+ *
+ * @return                      The allocated buffer on success;
+ *                              NULL on buffer exhaustion.
+ */
+int esp_ble_hci_trans_hs_cmd_tx(uint8_t *cmd);
+
+/**
+ * Sends ACL data from host to controller.
+ *
+ * @param om                    The ACL data packet to send.
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+int esp_ble_hci_trans_hs_acl_tx(struct os_mbuf *om);
+
+/**
+ * Allocates a flat buffer of the specified type.
+ *
+ * @param type                  The type of buffer to allocate; one of the
+ *                                  BLE_HCI_TRANS_BUF_[...] constants.
+ *
+ * @return                      The allocated buffer on success;
+ *                              NULL on buffer exhaustion.
+ */
+uint8_t *esp_ble_hci_trans_buf_alloc(int type);
+
+/**
+ * Frees the specified flat buffer.  The buffer must have been allocated via
+ * ble_hci_trans_buf_alloc().
+ *
+ * @param buf                   The buffer to free.
+ */
+void esp_ble_hci_trans_buf_free(uint8_t *buf);
+
+/**
+ * Configures the HCI transport to operate with a host.  The transport will
+ * execute specified callbacks upon receiving HCI packets from the controller.
+ *
+ * @param evt_cb                The callback to execute upon receiving an HCI
+ *                                  event.
+ * @param evt_arg               Optional argument to pass to the event
+ *                                  callback.
+ * @param acl_cb                The callback to execute upon receiving ACL
+ *                                  data.
+ * @param acl_arg               Optional argument to pass to the ACL
+ *                                  callback.
+ */
+void esp_ble_hci_trans_cfg_hs(ble_hci_trans_rx_cmd_fn *evt_cb,
+                          void *evt_arg,
+                          ble_hci_trans_rx_acl_fn *acl_cb,
+                          void *acl_arg);
+
+/**
+ * Resets the HCI module to a clean state.  Frees all buffers and reinitializes
+ * the underlying transport.
+ *
+ * @return                      0 on success;
+ *                              A BLE_ERR_[...] error code on failure.
+ */
+int esp_ble_hci_trans_reset(void);
+#endif
 struct os_mbuf;
 
 /* Initialization */
 void ble_transport_init(void);
 
 /* Allocators for supported data types */
+#if !SOC_ESP_NIMBLE_CONTROLLER
 void *ble_transport_alloc_cmd(void);
 void *ble_transport_alloc_evt(int discardable);
 struct os_mbuf *ble_transport_alloc_acl_from_hs(void);
@@ -45,13 +341,20 @@ struct os_mbuf *ble_transport_alloc_iso_from_ll(void);
 
 /* Generic deallocator for cmd/evt buffers */
 void ble_transport_free(void *buf);
+#endif
 
 /* Register put callback on acl_from_ll mbufs (for ll-hs flow control) */
 int ble_transport_register_put_acl_from_ll_cb(os_mempool_put_fn *cb);
 
-/* Send data to hs/ll side */
+#if CONFIG_BT_CONTROLLER_ENABLED
+#define ble_transport_to_ll_acl ble_hci_trans_hs_acl_tx
+#define ble_transport_to_ll_cmd ble_hci_trans_hs_cmd_tx
+#else
 int ble_transport_to_ll_cmd(void *buf);
 int ble_transport_to_ll_acl(struct os_mbuf *om);
+#endif
+
+/* Send data to hs/ll side */
 int ble_transport_to_ll_iso(struct os_mbuf *om);
 int ble_transport_to_hs_evt(void *buf);
 int ble_transport_to_hs_acl(struct os_mbuf *om);
diff --git a/nimble/transport/include/nimble/transport_impl.h b/nimble/transport/include/nimble/transport_impl.h
index 8d95c8920..d59733788 100644
--- a/nimble/transport/include/nimble/transport_impl.h
+++ b/nimble/transport/include/nimble/transport_impl.h
@@ -24,6 +24,9 @@
 extern "C" {
 #endif
 
+#include "os/os_mempool.h"
+#include "syscfg/syscfg.h"
+
 /* Init functions to be implemented for transport acting as HS/LL side */
 extern void ble_transport_ll_init(void);
 extern void ble_transport_hs_init(void);
diff --git a/nimble/transport/src/transport.c b/nimble/transport/src/transport.c
index c9b37a7e9..a6b150863 100644
--- a/nimble/transport/src/transport.c
+++ b/nimble/transport/src/transport.c
@@ -28,6 +28,10 @@
 #if BLE_TRANSPORT_IPC
 #include <nimble/transport/hci_ipc.h>
 #endif
+#include "esp_nimble_mem.h"
+
+int os_msys_buf_alloc(void);
+void os_msys_buf_free(void);
 
 #define OMP_FLAG_FROM_HS        (0x01)
 #define OMP_FLAG_FROM_LL        (0x02)
@@ -70,23 +74,24 @@
                                       BLE_MBUF_MEMBLOCK_OVERHEAD +         \
                                       BLE_HCI_DATA_HDR_SZ, OS_ALIGNMENT))
 
-static uint8_t pool_cmd_buf[ OS_MEMPOOL_BYTES(POOL_CMD_COUNT, POOL_CMD_SIZE) ];
+#if !SOC_ESP_NIMBLE_CONTROLLER || !CONFIG_BT_CONTROLLER_ENABLED
+static os_membuf_t *pool_cmd_buf;
 static struct os_mempool pool_cmd;
 
-static uint8_t pool_evt_buf[ OS_MEMPOOL_BYTES(POOL_EVT_COUNT, POOL_EVT_SIZE) ];
+static os_membuf_t *pool_evt_buf;
 static struct os_mempool pool_evt;
 
-static uint8_t pool_evt_lo_buf[ OS_MEMPOOL_BYTES(POOL_EVT_LO_COUNT, POOL_EVT_SIZE) ];
+static os_membuf_t *pool_evt_lo_buf;
 static struct os_mempool pool_evt_lo;
 
 #if POOL_ACL_COUNT > 0
-static uint8_t pool_acl_buf[ OS_MEMPOOL_BYTES(POOL_ACL_COUNT, POOL_ACL_SIZE) ];
+static os_membuf_t *pool_acl_buf;
 static struct os_mempool_ext pool_acl;
 static struct os_mbuf_pool mpool_acl;
 #endif
 
 #if POOL_ISO_COUNT > 0
-static uint8_t pool_iso_buf[ OS_MEMPOOL_BYTES(POOL_ISO_COUNT, POOL_ISO_SIZE) ];
+static os_membuf_t *pool_iso_buf;
 static struct os_mempool_ext pool_iso;
 static struct os_mbuf_pool mpool_iso;
 #endif
@@ -275,29 +280,29 @@ ble_transport_ipc_free(void *buf)
 static os_error_t
 ble_transport_acl_put(struct os_mempool_ext *mpe, void *data, void *arg)
 {
+    os_error_t err;
+    err = 0;
+
+#if MYNEWT_VAL(BLE_TRANSPORT_INT_FLOW_CTL)
     struct os_mbuf *om;
     struct os_mbuf_pkthdr *pkthdr;
-    bool do_put;
     bool from_ll;
-    os_error_t err;
+#endif
 
+#if MYNEWT_VAL(BLE_HS_FLOW_CTRL)
+    if (transport_put_acl_from_ll_cb) {
+        err = transport_put_acl_from_ll_cb(mpe, data, arg);
+    }
+#else
+    err = os_memblock_put_from_cb(&mpe->mpe_mp, data);
+#endif
+
+#if MYNEWT_VAL(BLE_TRANSPORT_INT_FLOW_CTL)
     om = data;
     pkthdr = OS_MBUF_PKTHDR(om);
 
-    do_put = true;
     from_ll = (pkthdr->omp_flags & OMP_FLAG_FROM_MASK) == OMP_FLAG_FROM_LL;
-    err = 0;
 
-    if (from_ll && transport_put_acl_from_ll_cb) {
-        err = transport_put_acl_from_ll_cb(mpe, data, arg);
-        do_put = false;
-    }
-
-    if (do_put) {
-        err = os_memblock_put_from_cb(&mpe->mpe_mp, data);
-    }
-
-#if BLE_TRANSPORT_IPC_ON_HS
     if (from_ll && !err) {
         hci_ipc_put(HCI_IPC_TYPE_ACL);
     }
@@ -307,6 +312,68 @@ ble_transport_acl_put(struct os_mempool_ext *mpe, void *data, void *arg)
 }
 #endif
 
+void ble_buf_free(void)
+{
+    os_msys_buf_free();
+
+    nimble_platform_mem_free(pool_evt_buf);
+    pool_evt_buf = NULL;
+    nimble_platform_mem_free(pool_evt_lo_buf);
+    pool_evt_lo_buf = NULL;
+    nimble_platform_mem_free(pool_cmd_buf);
+    pool_cmd_buf = NULL;
+#if POOL_ACL_COUNT > 0
+    nimble_platform_mem_free(pool_acl_buf);
+    pool_acl_buf = NULL;
+#endif
+#if POOL_ISO_COUNT > 0
+    nimble_platform_mem_free(pool_iso_buf);
+    pool_iso_buf = NULL;
+#endif
+}
+
+esp_err_t ble_buf_alloc(void)
+{
+    if (os_msys_buf_alloc()) {
+        return ESP_ERR_NO_MEM;
+    }
+
+    pool_evt_buf = (os_membuf_t *) nimble_platform_mem_calloc(1,
+                   (sizeof(os_membuf_t) * OS_MEMPOOL_SIZE(MYNEWT_VAL(BLE_TRANSPORT_EVT_COUNT),
+                           MYNEWT_VAL(BLE_TRANSPORT_EVT_SIZE))));
+
+    pool_evt_lo_buf = (os_membuf_t *) nimble_platform_mem_calloc(1,
+                      (sizeof(os_membuf_t) * OS_MEMPOOL_SIZE(MYNEWT_VAL(BLE_TRANSPORT_EVT_DISCARDABLE_COUNT),
+                              MYNEWT_VAL(BLE_TRANSPORT_EVT_SIZE))));
+
+    pool_cmd_buf = (os_membuf_t *) nimble_platform_mem_calloc(1,
+                   (sizeof(os_membuf_t) * OS_MEMPOOL_SIZE(POOL_CMD_COUNT, POOL_CMD_SIZE)));
+
+#if POOL_ACL_COUNT > 0
+    pool_acl_buf = (os_membuf_t *) nimble_platform_mem_calloc(1,
+                   (sizeof(os_membuf_t) * OS_MEMPOOL_SIZE(POOL_ACL_COUNT,
+                           POOL_ACL_SIZE)));
+    if(!pool_acl_buf) {
+       ble_buf_free();
+       return ESP_ERR_NO_MEM;
+    }
+#endif
+#if POOL_ISO_COUNT > 0
+    pool_iso_buf = (os_membuf_t *) nimble_platform_mem_calloc(1,
+                    sizeof(os_membuf_t) * OS_MEMPOOL_SIZE(POOL_ISO_COUNT,
+                           POOL_ISO_SIZE));
+    if(!pool_iso_buf) {
+       ble_buf_free();
+       return ESP_ERR_NO_MEM;
+    }
+#endif
+    if (!pool_evt_buf || !pool_evt_lo_buf || !pool_cmd_buf ) {
+        ble_buf_free();
+        return ESP_ERR_NO_MEM;
+    }
+    return ESP_OK;
+}
+
 void
 ble_transport_init(void)
 {
@@ -349,6 +416,22 @@ ble_transport_init(void)
 #endif
 }
 
+void
+ble_transport_deinit(void)
+{
+    int rc = 0;
+    rc = os_mempool_ext_clear(&pool_acl);
+    SYSINIT_PANIC_ASSERT(rc == 0);
+
+    rc = os_mempool_clear(&pool_evt_lo);
+    SYSINIT_PANIC_ASSERT(rc == 0);
+
+    rc = os_mempool_clear(&pool_evt);
+    SYSINIT_PANIC_ASSERT(rc == 0);
+
+    rc = os_mempool_clear(&pool_cmd);
+    SYSINIT_PANIC_ASSERT(rc == 0);
+}
 int
 ble_transport_register_put_acl_from_ll_cb(os_mempool_put_fn (*cb))
 {
@@ -373,3 +456,5 @@ ble_transport_ipc_buf_evt_type_get(void *buf)
     return 0;
 }
 #endif
+#endif
+
diff --git a/porting/nimble/src/nimble_port.c b/porting/nimble/src/nimble_port.c
index 402a77782..1aeb000d3 100644
--- a/porting/nimble/src/nimble_port.c
+++ b/porting/nimble/src/nimble_port.c
@@ -39,7 +39,6 @@
 #endif
 
 
-#include "nimble/ble_hci_trans.h"
 
 #include "esp_intr_alloc.h"
 #include "freertos/FreeRTOS.h"
@@ -105,9 +104,8 @@ esp_err_t esp_nimble_init(void)
     /* Initialize the global memory pool */
     os_mempool_module_init();
     os_msys_init();
-    /* Initialize transport */
-    ble_transport_init();
-#endif 
+
+#endif
     /* Initialize the host */
     ble_transport_hs_init();
 
diff --git a/porting/npl/freertos/src/npl_os_freertos.c b/porting/npl/freertos/src/npl_os_freertos.c
index 4c3e68bd8..d3cd19587 100644
--- a/porting/npl/freertos/src/npl_os_freertos.c
+++ b/porting/npl/freertos/src/npl_os_freertos.c
@@ -45,8 +45,8 @@ static const char *TAG = "Timer";
 #define OS_MEM_ALLOC (1)
 
 #if CONFIG_BT_NIMBLE_ENABLED
-#define BT_LE_HCI_EVT_HI_BUF_COUNT MYNEWT_VAL(BLE_HCI_EVT_HI_BUF_COUNT)
-#define BT_LE_HCI_EVT_LO_BUF_COUNT MYNEWT_VAL(BLE_HCI_EVT_LO_BUF_COUNT)
+#define BT_LE_HCI_EVT_HI_BUF_COUNT MYNEWT_VAL(BLE_TRANSPORT_EVT_COUNT)
+#define BT_LE_HCI_EVT_LO_BUF_COUNT MYNEWT_VAL(BLE_TRANSPORT_EVT_DISCARDABLE_COUNT)
 #define BT_LE_MAX_EXT_ADV_INSTANCES MYNEWT_VAL(BLE_MULTI_ADV_INSTANCES)
 #define BT_LE_MAX_CONNECTIONS MYNEWT_VAL(BLE_MAX_CONNECTIONS)
 #else