extmod/modbluetooth: Add optional 4th arg to gattc_write for write mode.

This allows the user to explicitly select the behaviour of the write to the
remote peripheral.  This is needed for peripherals that have
characteristics with WRITE_NO_RESPONSE set (instead of normal WRITE).  The
function's signature is now:

    BLE.gattc_write(conn_handle, value_handle, data, mode=0)

mode=0 means write without response, while mode=1 means write with
response.  The latter was the original behaviour so this commit is a change
in behaviour of this method, and one should specify 1 as the 4th argument
to get back the old behaviour.

In the future there could be more modes supported, such as long writes.

docs/library/ubluetooth.rst

@@ -310,12 +310,23 @@ Central Role (GATT Client)
 
     On success, the ``_IRQ_GATTC_READ_RESULT`` event will be raised.
 
-.. method:: BLE.gattc_write(conn_handle, value_handle, data)
+.. method:: BLE.gattc_write(conn_handle, value_handle, data, mode=0)
 
     Issue a remote write to a connected peripheral for the specified
     characteristic or descriptor handle.
 
-    On success, the ``_IRQ_GATTC_WRITE_STATUS`` event will be raised.
+    The argument *mode* specifies the write behaviour, with the currently
+    supported values being:
+
+        * ``mode=0`` (default) is a write-without-response: the write will
+          be sent to the remote peripheral but no confirmation will be
+          returned, and no event will be raised.
+        * ``mode=1`` is a write-with-response: the remote peripheral is
+          requested to send a response/acknowledgement that it received the
+          data.
+
+    If a response is received from the remote peripheral the
+    ``_IRQ_GATTC_WRITE_STATUS`` event will be raised.
 
 
 class UUID

extmod/modbluetooth.c

@@ -641,9 +641,13 @@ STATIC mp_obj_t bluetooth_ble_gattc_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);
     size_t len = bufinfo.len;
-    return bluetooth_handle_errno(mp_bluetooth_gattc_write(conn_handle, value_handle, bufinfo.buf, &len));
+    unsigned int mode = MP_BLUETOOTH_WRITE_MODE_NO_RESPONSE;
+    if (n_args == 5) {
+        mode = mp_obj_get_int(args[4]);
+    }
+    return bluetooth_handle_errno(mp_bluetooth_gattc_write(conn_handle, value_handle, bufinfo.buf, &len, mode));
 }
-STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gattc_write_obj, 4, 4, bluetooth_ble_gattc_write);
+STATIC MP_DEFINE_CONST_FUN_OBJ_VAR_BETWEEN(bluetooth_ble_gattc_write_obj, 4, 5, bluetooth_ble_gattc_write);
 
 #endif // MICROPY_PY_BLUETOOTH_ENABLE_CENTRAL_MODE
 

extmod/modbluetooth.h

@@ -65,6 +65,10 @@
 #define MP_BLUETOOTH_CHARACTERISTIC_FLAG_WRITE    (1 << 3)
 #define MP_BLUETOOTH_CHARACTERISTIC_FLAG_NOTIFY   (1 << 4)
 
+// For mp_bluetooth_gattc_write, the mode parameter
+#define MP_BLUETOOTH_WRITE_MODE_NO_RESPONSE     (0)
+#define MP_BLUETOOTH_WRITE_MODE_WITH_RESPONSE   (1)
+
 // Type value also doubles as length.
 #define MP_BLUETOOTH_UUID_TYPE_16  (2)
 #define MP_BLUETOOTH_UUID_TYPE_32  (4)
@@ -219,7 +223,7 @@ int mp_bluetooth_gattc_discover_descriptors(uint16_t conn_handle, uint16_t start
 int mp_bluetooth_gattc_read(uint16_t conn_handle, uint16_t value_handle);
 
 // Write the value to the remote peripheral.
-int mp_bluetooth_gattc_write(uint16_t conn_handle, uint16_t value_handle, const uint8_t *value, size_t *value_len);
+int mp_bluetooth_gattc_write(uint16_t conn_handle, uint16_t value_handle, const uint8_t *value, size_t *value_len, unsigned int mode);
 #endif
 
 /////////////////////////////////////////////////////////////////////////////

extmod/modbluetooth_nimble.c

@@ -816,8 +816,15 @@ STATIC int ble_gatt_attr_write_cb(uint16_t conn_handle, const struct ble_gatt_er
 }
 
 // Write the value to the remote peripheral.
-int mp_bluetooth_gattc_write(uint16_t conn_handle, uint16_t value_handle, const uint8_t *value, size_t *value_len) {
+int mp_bluetooth_gattc_write(uint16_t conn_handle, uint16_t value_handle, const uint8_t *value, size_t *value_len, unsigned int mode) {
-    int err = ble_gattc_write_flat(conn_handle, value_handle, value, *value_len, &ble_gatt_attr_write_cb, NULL);
+    int err;
+    if (mode == MP_BLUETOOTH_WRITE_MODE_NO_RESPONSE) {
+        err = ble_gattc_write_no_rsp_flat(conn_handle, value_handle, value, *value_len);
+    } else if (mode == MP_BLUETOOTH_WRITE_MODE_WITH_RESPONSE) {
+        err = ble_gattc_write_flat(conn_handle, value_handle, value, *value_len, &ble_gatt_attr_write_cb, NULL);
+    } else {
+        err = BLE_HS_EINVAL;
+    }
     return ble_hs_err_to_errno(err);
 }