micropython · jimmo · Jul 23, 2021 · Aug 13, 2021
diff --git a/docs/library/bluetooth.rst b/docs/library/bluetooth.rst
@@ -485,10 +485,14 @@ writes from a client to a given characteristic, use
     Reads the local value for this handle (which has either been written by
     :meth:`gatts_write <BLE.gatts_write>` or by a remote client).
 
-.. method:: BLE.gatts_write(value_handle, data, /)
+.. method:: BLE.gatts_write(value_handle, data, send_update=False, /)
 
     Writes the local value for this handle, which can be read by a client.
 
+    If *send_update* is ``True``, then any subscribed clients will be notified
+    (or indicated, depending on what they're subscribed to and which operations
+    the characteristic supports) about this write.
+
 .. method:: BLE.gatts_notify(conn_handle, value_handle, data=None, /)
 
     Sends a notification request to a connected client.
@@ -499,17 +503,20 @@ writes from a client to a given characteristic, use
     Otherwise, if *data* is ``None``, then the current local value (as
     set with :meth:`gatts_write <BLE.gatts_write>`) will be sent.
 
-.. method:: BLE.gatts_indicate(conn_handle, value_handle, /)
+    **Note:** The notification will be sent regardless of the subscription
+    status of the client to this characteristic.
 
-    Sends an indication request to a connected client.
+.. method:: BLE.gatts_indicate(conn_handle, value_handle, /)
 
-    **Note:** This does not currently support sending a custom value, it will
-    always send the current local value (as set with :meth:`gatts_write
-    <BLE.gatts_write>`).
+    Sends an indication request containing the characteristic's current value to
+    a connected client.
 
     On acknowledgment (or failure, e.g. timeout), the
     ``_IRQ_GATTS_INDICATE_DONE`` event will be raised.
 
+    **Note:** The indication will be sent regardless of the subscription
+    status of the client to this characteristic.
+
 .. method:: BLE.gatts_set_buffer(value_handle, len, append=False, /)
 
     Sets the internal buffer size for a value in bytes. This will limit the

diff --git a/extmod/btstack/modbluetooth_btstack.c b/extmod/btstack/modbluetooth_btstack.c
@@ -1085,11 +1085,14 @@ int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *valu
     return mp_bluetooth_gatts_db_read(MP_STATE_PORT(bluetooth_btstack_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len) {
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update) {
     DEBUG_printf("mp_bluetooth_gatts_write\n");
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;
     }
+    if (send_update) {
+        return MP_EOPNOTSUPP;
+    }
     return mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_btstack_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 

diff --git a/extmod/modbluetooth.c b/extmod/modbluetooth.c
@@ -717,15 +717,17 @@ STATIC mp_obj_t bluetooth_ble_gatts_read(mp_obj_t self_in, mp_obj_t value_handle
 }
 STATIC MP_DEFINE_CONST_FUN_OBJ_2(bluetooth_ble_gatts_read_obj, bluetooth_ble_gatts_read);
 
-STATIC mp_obj_t bluetooth_ble_gatts_write(mp_obj_t self_in, mp_obj_t value_handle_in, mp_obj_t data) {
-    (void)self_in;
+STATIC mp_obj_t bluetooth_ble_gatts_write(size_t n_args, const mp_obj_t *args) {
     mp_buffer_info_t bufinfo = {0};
-    mp_get_buffer_raise(data, &bufinfo, MP_BUFFER_READ);
-    int err = mp_bluetooth_gatts_write(mp_obj_get_int(value_handle_in), bufinfo.buf, bufinfo.len);
-    bluetooth_handle_errno(err);
+    mp_get_buffer_raise(args[2], &bufinfo, MP_BUFFER_READ);
+    bool send_update = false;
+    if (n_args > 3) {
+        send_update = mp_obj_is_true(args[3]);
+    }
+    bluetooth_handle_errno(mp_bluetooth_gatts_write(mp_obj_get_int(args[1]), bufinfo.buf, bufinfo.len, send_update));
     return MP_OBJ_NEW_SMALL_INT(bufinfo.len);
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_3(bluetooth_ble_gatts_write_obj, bluetooth_ble_gatts_write);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gatts_write_obj, 3, 4, bluetooth_ble_gatts_write);
 
 STATIC mp_obj_t bluetooth_ble_gatts_notify(size_t n_args, const mp_obj_t *args) {
     mp_int_t conn_handle = mp_obj_get_int(args[1]);

diff --git a/extmod/modbluetooth.h b/extmod/modbluetooth.h
@@ -334,8 +334,8 @@ int mp_bluetooth_gatts_register_service_end(void);
 
 // Read the value from the local gatts db (likely this has been written by a central).
 int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *value_len);
-// Write a value to the local gatts db (ready to be queried by a central).
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len);
+// Write a value to the local gatts db (ready to be queried by a central). Optionally send notifications/indications.
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update);
 // Notify the central that it should do a read.
 int mp_bluetooth_gatts_notify(uint16_t conn_handle, uint16_t value_handle);
 // Notify the central, including a data payload. (Note: does not set the gatts db value).

diff --git a/extmod/nimble/modbluetooth_nimble.c b/extmod/nimble/modbluetooth_nimble.c
@@ -512,6 +512,11 @@ STATIC int central_gap_event_cb(struct ble_gap_event *event, void *arg) {
 
             return 0;
         }
+
+        case BLE_GAP_EVENT_SUBSCRIBE: {
+            DEBUG_printf("central_gap_event_cb: subscribe: handle=%d, reason=%d notify=%d indicate=%d \n", event->subscribe.attr_handle, event->subscribe.reason, event->subscribe.cur_notify, event->subscribe.cur_indicate);
+            return 0;
+        }
     }
 
     return commmon_gap_event_cb(event, arg);
@@ -1004,11 +1009,15 @@ int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *valu
     return mp_bluetooth_gatts_db_read(MP_STATE_PORT(bluetooth_nimble_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len) {
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update) {
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;
     }
-    return mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_nimble_root_pointers)->gatts_db, value_handle, value, value_len);
+    int err = mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_nimble_root_pointers)->gatts_db, value_handle, value, value_len);
+    if (err == 0 && send_update) {
+        ble_gatts_chr_updated(value_handle);
+    }
+    return err;
 }
 
 // TODO: Could use ble_gatts_chr_updated to send to all subscribed centrals.

diff --git a/ports/zephyr/modbluetooth_zephyr.c b/ports/zephyr/modbluetooth_zephyr.c
@@ -308,10 +308,13 @@ int mp_bluetooth_gatts_read(uint16_t value_handle, uint8_t **value, size_t *valu
     return mp_bluetooth_gatts_db_read(MP_STATE_PORT(bluetooth_zephyr_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 
-int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len) {
+int mp_bluetooth_gatts_write(uint16_t value_handle, const uint8_t *value, size_t value_len, bool send_update) {
     if (!mp_bluetooth_is_active()) {
         return ERRNO_BLUETOOTH_NOT_ACTIVE;
     }
+    if (send_update) {
+        return MP_EOPNOTSUPP;
+    }
     return mp_bluetooth_gatts_db_write(MP_STATE_PORT(bluetooth_zephyr_root_pointers)->gatts_db, value_handle, value, value_len);
 }
 

diff --git a/tests/multi_bluetooth/ble_subscribe.py b/tests/multi_bluetooth/ble_subscribe.py
@@ -0,0 +1,246 @@
+# Test for sending notifications to subscribed clients.
+
+from micropython import const
+import time, machine, bluetooth
+
+TIMEOUT_MS = 5000
+
+_IRQ_CENTRAL_CONNECT = const(1)
+_IRQ_CENTRAL_DISCONNECT = const(2)
+_IRQ_GATTS_WRITE = const(3)
+_IRQ_PERIPHERAL_CONNECT = const(7)
+_IRQ_PERIPHERAL_DISCONNECT = const(8)
+_IRQ_GATTC_CHARACTERISTIC_RESULT = const(11)
+_IRQ_GATTC_CHARACTERISTIC_DONE = const(12)
+_IRQ_GATTC_DESCRIPTOR_RESULT = const(13)
+_IRQ_GATTC_DESCRIPTOR_DONE = const(14)
+_IRQ_GATTC_READ_RESULT = const(15)
+_IRQ_GATTC_READ_DONE = const(16)
+_IRQ_GATTC_WRITE_DONE = const(17)
+_IRQ_GATTC_NOTIFY = const(18)
+_IRQ_GATTC_INDICATE = const(19)
+
+_CCCD_UUID = bluetooth.UUID(const(0x2902))
+
+SERVICE_UUID = bluetooth.UUID("A5A5A5A5-FFFF-9999-1111-5A5A5A5A5A5A")
+CHAR_UUID = bluetooth.UUID("00000000-1111-2222-3333-444444444444")
+CHAR = (
+    CHAR_UUID,
+    bluetooth.FLAG_READ | bluetooth.FLAG_WRITE | bluetooth.FLAG_NOTIFY | bluetooth.FLAG_INDICATE,
+)
+SERVICE = (
+    SERVICE_UUID,
+    (CHAR,),
+)
+SERVICES = (SERVICE,)
+
+waiting_events = {}
+
+
+def irq(event, data):
+    if event == _IRQ_CENTRAL_CONNECT:
+        print("_IRQ_CENTRAL_CONNECT")
+        waiting_events[event] = data[0]
+    elif event == _IRQ_CENTRAL_DISCONNECT:
+        print("_IRQ_CENTRAL_DISCONNECT")
+    elif event == _IRQ_GATTS_WRITE:
+        print("_IRQ_GATTS_WRITE", ble.gatts_read(data[-1]))
+    elif event == _IRQ_PERIPHERAL_CONNECT:
+        print("_IRQ_PERIPHERAL_CONNECT")
+        waiting_events[event] = data[0]
+    elif event == _IRQ_PERIPHERAL_DISCONNECT:
+        print("_IRQ_PERIPHERAL_DISCONNECT")
+    elif event == _IRQ_GATTC_CHARACTERISTIC_RESULT:
+        # conn_handle, def_handle, value_handle, properties, uuid = data
+        if data[-1] == CHAR_UUID:
+            print("_IRQ_GATTC_CHARACTERISTIC_RESULT", data[-1])
+            waiting_events[event] = data[2]
+        else:
+            return
+    elif event == _IRQ_GATTC_CHARACTERISTIC_DONE:
+        print("_IRQ_GATTC_CHARACTERISTIC_DONE")
+    elif event == _IRQ_GATTC_DESCRIPTOR_RESULT:
+        # conn_handle, dsc_handle, uuid = data
+        if data[-1] == _CCCD_UUID:
+            print("_IRQ_GATTC_DESCRIPTOR_RESULT", data[-1])
+            waiting_events[event] = data[1]
+        else:
+            return
+    elif event == _IRQ_GATTC_DESCRIPTOR_DONE:
+        print("_IRQ_GATTC_DESCRIPTOR_DONE")
+    elif event == _IRQ_GATTC_READ_RESULT:
+        print("_IRQ_GATTC_READ_RESULT", bytes(data[-1]))
+    elif event == _IRQ_GATTC_READ_DONE:
+        print("_IRQ_GATTC_READ_DONE", data[-1])
+    elif event == _IRQ_GATTC_WRITE_DONE:
+        print("_IRQ_GATTC_WRITE_DONE", data[-1])
+    elif event == _IRQ_GATTC_NOTIFY:
+        print("_IRQ_GATTC_NOTIFY", bytes(data[-1]))
+    elif event == _IRQ_GATTC_INDICATE:
+        print("_IRQ_GATTC_NOTIFY", bytes(data[-1]))
+
+    if event not in waiting_events:
+        waiting_events[event] = None
+
+
+def wait_for_event(event, timeout_ms):
+    t0 = time.ticks_ms()
+    while time.ticks_diff(time.ticks_ms(), t0) < timeout_ms:
+        if event in waiting_events:
+            return waiting_events.pop(event)
+        machine.idle()
+    raise ValueError("Timeout waiting for {}".format(event))
+
+
+# Acting in peripheral role.
+def instance0():
+    multitest.globals(BDADDR=ble.config("mac"))
+    ((char_handle,),) = ble.gatts_register_services(SERVICES)
+    print("gap_advertise")
+    ble.gap_advertise(20_000, b"\x02\x01\x06\x04\xffMPY")  # \x04\x09MPY
+    multitest.next()
+    try:
+        # Write initial characteristic value (will be read by client).
+        ble.gatts_write(char_handle, "periph0")  ###
+
+        # Wait for central to connect to us.
+        conn_handle = wait_for_event(_IRQ_CENTRAL_CONNECT, TIMEOUT_MS * 10)
+
+        # A
+        # Wait for a write to the characteristic from the central (to synchronise).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync A")
+        # This should be local-only.
+        ble.gatts_write(char_handle, "periph1")
+        time.sleep_ms(100)
+        # Update local-only, then force notify.
+        ble.gatts_write(char_handle, "periph2")
+        ble.gatts_notify(conn_handle, char_handle)  ###
+        time.sleep_ms(100)
+        # Update local and notify subscribers. No notification should be sent.
+        ble.gatts_write(char_handle, "periph3", True)
+        time.sleep_ms(100)
+        multitest.broadcast("A")
+
+        # B
+        # Synchronise with the client (which should now be subscribed for notify).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync B")
+        # This should be local-only (send_update=False).
+        ble.gatts_write(char_handle, "periph4", False)
+        time.sleep_ms(100)
+        # This should notify the subscribed client.
+        ble.gatts_write(char_handle, "periph5", True)  ###
+        time.sleep_ms(100)
+        multitest.broadcast("B")
+
+        # C
+        # Synchronise with the client (which should now be subscribed for indicate).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync C")
+        # This should be local-only (send_update=False).
+        ble.gatts_write(char_handle, "periph6", False)
+        time.sleep_ms(100)
+        # This should indicate the subscribed client.
+        ble.gatts_write(char_handle, "periph7", True)  ###
+        time.sleep_ms(100)
+        multitest.broadcast("C")
+
+        # D
+        # Synchronise with the client (which should now be unsubscribed).
+        wait_for_event(_IRQ_GATTS_WRITE, TIMEOUT_MS)
+        print("sync D")
+        # This should be local-only (send_update=False).
+        ble.gatts_write(char_handle, "periph8", False)
+        time.sleep_ms(100)
+        # This should be local-only (no more subscribers).
+        ble.gatts_write(char_handle, "periph9", True)
+        time.sleep_ms(100)
+        # Update local-only, then another force notify.
+        ble.gatts_write(char_handle, "periph10")
+        ble.gatts_notify(conn_handle, char_handle)  ###
+        time.sleep_ms(100)
+        multitest.broadcast("D")
+
+        # Wait for the central to disconnect.
+        wait_for_event(_IRQ_CENTRAL_DISCONNECT, TIMEOUT_MS)
+    finally:
+        ble.active(0)
+
+
+# Acting in central role.
+def instance1():
+    multitest.next()
+    try:
+        # Connect to peripheral and then disconnect.
+        print("gap_connect")
+        ble.gap_connect(*BDADDR)
+        conn_handle = wait_for_event(_IRQ_PERIPHERAL_CONNECT, TIMEOUT_MS)
+
+        # Discover characteristics.
+        ble.gattc_discover_characteristics(conn_handle, 1, 65535)
+        value_handle = wait_for_event(_IRQ_GATTC_CHARACTERISTIC_RESULT, TIMEOUT_MS)
+        wait_for_event(_IRQ_GATTC_CHARACTERISTIC_DONE, TIMEOUT_MS)
+
+        # Discover CCCD.
+        ble.gattc_discover_descriptors(conn_handle, value_handle, value_handle + 5)
+        cccd_handle = wait_for_event(_IRQ_GATTC_DESCRIPTOR_RESULT, TIMEOUT_MS)
+        wait_for_event(_IRQ_GATTC_DESCRIPTOR_DONE, TIMEOUT_MS)
+
+        # Issue read of characteristic, should get initial value.
+        print("gattc_read")
+        ble.gattc_read(conn_handle, value_handle)
+        wait_for_event(_IRQ_GATTC_READ_RESULT, TIMEOUT_MS)
+
+        # While the four states are active, all incoming notifications
+        # and indications will be printed by the event handler. We
+        # should only expect to see certain ones.
+
+        # Start unsubscribed.
+        # Write to the characteristic (triggers A).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central0", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for A to complete.
+        multitest.wait("A")
+
+        # Subscribe for notify.
+        ble.gattc_write(conn_handle, cccd_handle, b"\x01\x00", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Write to the characteristic (triggers B).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central1", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for B to complete.
+        multitest.wait("B")
+
+        # Subscribe for indicate.
+        ble.gattc_write(conn_handle, cccd_handle, b"\x02\x00", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Write to the characteristic (triggers C).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central2", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for C to complete.
+        multitest.wait("C")
+
+        # Unsubscribe.
+        ble.gattc_write(conn_handle, cccd_handle, b"\x00\x00", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Write to the characteristic (triggers D).
+        print("gattc_write")
+        ble.gattc_write(conn_handle, value_handle, "central3", 1)
+        wait_for_event(_IRQ_GATTC_WRITE_DONE, TIMEOUT_MS)
+        # Wait for D to complete.
+        multitest.wait("D")
+
+        # Disconnect from peripheral.
+        print("gap_disconnect:", ble.gap_disconnect(conn_handle))
+        wait_for_event(_IRQ_PERIPHERAL_DISCONNECT, TIMEOUT_MS)
+    finally:
+        ble.active(0)
+
+
+ble = bluetooth.BLE()
+ble.active(1)
+ble.irq(irq)