extmod/modbluetooth: Add connection interval to gap_connect.

This forwards through directly to the NimBLE and BTStack connect functions.

Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

docs/library/bluetooth.rst

@@ -359,7 +359,7 @@ Central Role
 
 A central device can connect to peripherals that it has discovered using the observer role (see :meth:`gap_scan<BLE.gap_scan>`) or with a known address.
 
-.. method:: BLE.gap_connect(addr_type, addr, scan_duration_ms=2000, /)
+.. method:: BLE.gap_connect(addr_type, addr, scan_duration_ms=2000, min_conn_interval_us=None, max_conn_interval_us=None, /)
 
     Connect to a peripheral.
 
@@ -367,6 +367,15 @@ A central device can connect to peripherals that it has discovered using the obs
 
     On success, the ``_IRQ_PERIPHERAL_CONNECT`` event will be raised.
 
+    The device will wait up to *scan_duration_ms* to receive an advertising
+    payload from the device.
+
+    The connection interval can be configured in **micro**\ seconds using either
+    or both of *min_conn_interval_us* and *max_conn_interval_us*. Otherwise a
+    default interval will be chosen, typically between 30000 and 50000
+    microseconds. A shorter interval will increase throughput, at the expense
+    of power usage.
+
 
 Peripheral Role
 ---------------

extmod/btstack/modbluetooth_btstack.c

@@ -1265,13 +1265,13 @@ int mp_bluetooth_gap_scan_stop(void) {
     return 0;
 }
 
-int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms) {
+int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms, int32_t min_conn_interval_us, int32_t max_conn_interval_us) {
     DEBUG_printf("mp_bluetooth_gap_peripheral_connect\n");
 
     uint16_t conn_scan_interval = 60000 / 625;
     uint16_t conn_scan_window = 30000 / 625;
-    uint16_t conn_interval_min = 10000 / 1250;
-    uint16_t conn_interval_max = 30000 / 1250;
+    uint16_t conn_interval_min = (min_conn_interval_us ? min_conn_interval_us : 10000) / 1250;
+    uint16_t conn_interval_max = (max_conn_interval_us ? max_conn_interval_us : 30000) / 1250;
     uint16_t conn_latency = 4;
     uint16_t supervision_timeout = duration_ms / 10; // default = 720
     uint16_t min_ce_length = 10000 / 625;

extmod/modbluetooth.c

@@ -637,14 +637,22 @@ STATIC mp_obj_t bluetooth_ble_gap_connect(size_t n_args, const mp_obj_t *args) {
         mp_raise_ValueError(MP_ERROR_TEXT("invalid addr"));
     }
     mp_int_t scan_duration_ms = MP_BLUETOOTH_CONNECT_DEFAULT_SCAN_DURATION_MS;
-    if (n_args == 4) {
+    mp_int_t min_conn_interval_us = 0;
+    mp_int_t max_conn_interval_us = 0;
+    if (n_args >= 4 && args[3] != mp_const_none) {
         scan_duration_ms = mp_obj_get_int(args[3]);
     }
+    if (n_args >= 5 && args[4] != mp_const_none) {
+        min_conn_interval_us = mp_obj_get_int(args[4]);
+    }
+    if (n_args >= 6 && args[5] != mp_const_none) {
+        max_conn_interval_us = mp_obj_get_int(args[5]);
+    }
 
-    int err = mp_bluetooth_gap_peripheral_connect(addr_type, bufinfo.buf, scan_duration_ms);
+    int err = mp_bluetooth_gap_peripheral_connect(addr_type, bufinfo.buf, scan_duration_ms, min_conn_interval_us, max_conn_interval_us);
     return bluetooth_handle_errno(err);
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_connect_obj, 3, 4, bluetooth_ble_gap_connect);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gap_connect_obj, 3, 6, bluetooth_ble_gap_connect);
 
 STATIC mp_obj_t bluetooth_ble_gap_scan(size_t n_args, const mp_obj_t *args) {
     // Default is indefinite scan, with the NimBLE "background scan" interval and window.

extmod/modbluetooth.h

@@ -370,7 +370,7 @@ int mp_bluetooth_gap_scan_start(int32_t duration_ms, int32_t interval_us, int32_
 int mp_bluetooth_gap_scan_stop(void);
 
 // Connect to a found peripheral.
-int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms);
+int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms, int32_t min_conn_interval_us, int32_t max_conn_interval_us);
 #endif
 
 #if MICROPY_PY_BLUETOOTH_ENABLE_GATT_CLIENT

extmod/nimble/modbluetooth_nimble.c

@@ -1202,7 +1202,7 @@ STATIC int peripheral_gap_event_cb(struct ble_gap_event *event, void *arg) {
     return commmon_gap_event_cb(event, arg);
 }
 
-int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms) {
+int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms, int32_t min_conn_interval_us, int32_t max_conn_interval_us) {
     DEBUG_printf("mp_bluetooth_gap_peripheral_connect\n");
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;
@@ -1211,12 +1211,14 @@ int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr,
         mp_bluetooth_gap_scan_stop();
     }
 
-    // TODO: This is the same as ble_gap_conn_params_dflt (i.e. passing NULL).
-    STATIC const struct ble_gap_conn_params params = {
+    uint16_t conn_interval_min = min_conn_interval_us ? min_conn_interval_us / BLE_HCI_CONN_ITVL : BLE_GAP_INITIAL_CONN_ITVL_MIN;
+    uint16_t conn_interval_max = max_conn_interval_us ? max_conn_interval_us / BLE_HCI_CONN_ITVL : BLE_GAP_INITIAL_CONN_ITVL_MAX;
+
+    const struct ble_gap_conn_params params = {
         .scan_itvl = 0x0010,
         .scan_window = 0x0010,
-        .itvl_min = BLE_GAP_INITIAL_CONN_ITVL_MIN,
-        .itvl_max = BLE_GAP_INITIAL_CONN_ITVL_MAX,
+        .itvl_min = conn_interval_min,
+        .itvl_max = conn_interval_max,
         .latency = BLE_GAP_INITIAL_CONN_LATENCY,
         .supervision_timeout = BLE_GAP_INITIAL_SUPERVISION_TIMEOUT,
         .min_ce_len = BLE_GAP_INITIAL_CONN_MIN_CE_LEN,

ports/zephyr/modbluetooth_zephyr.c

@@ -400,7 +400,7 @@ int mp_bluetooth_gap_scan_stop(void) {
     return bt_err_to_errno(err);
 }
 
-int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms) {
+int mp_bluetooth_gap_peripheral_connect(uint8_t addr_type, const uint8_t *addr, int32_t duration_ms, int32_t min_conn_interval_us, int32_t max_conn_interval_us) {
     DEBUG_printf("mp_bluetooth_gap_peripheral_connect\n");
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;