extmod/modbluetooth: Add send_update arg to gatts_write.

This allows the write to trigger a notification or indication, but only to
subscribed clients. This is different to gatts_notify/gatts_indicate,
which will unconditionally notify/indicate.
Signed-off-by: Jim Mussared <jim.mussared@gmail.com>

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

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);
 }
 

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]);

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).

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.

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);
 }