Make UARTService characteristics be at least as large as max MTU-3

Author: dhalbert

.pre-commit-config.yaml

@@ -18,7 +18,7 @@ repos:
       - id: end-of-file-fixer
       - id: trailing-whitespace
   - repo: https://github.com/pycqa/pylint
-    rev: v2.17.4
+    rev: v3.3.1
     hooks:
       - id: pylint
         name: pylint (library code)

adafruit_ble/characteristics/stream.py

@@ -53,7 +53,7 @@ def write(self, buf: ReadableBuffer) -> None:
 class StreamOut(ComplexCharacteristic):
     """Output stream from the Service server."""
 
-    def __init__(
+    def __init__(  # pylint: disable=too-many-arguments
         self,
         *,
         uuid: Optional[UUID] = None,
@@ -66,7 +66,11 @@ def __init__(
         self._timeout = timeout
         self._buffer_size = buffer_size
         super().__init__(
-            uuid=uuid, properties=properties, read_perm=read_perm, write_perm=write_perm
+            uuid=uuid,
+            properties=properties,
+            read_perm=read_perm,
+            write_perm=write_perm,
+            max_length=buffer_size,
         )
 
     def bind(
@@ -88,7 +92,7 @@ def bind(
 class StreamIn(ComplexCharacteristic):
     """Input stream into the Service server."""
 
-    def __init__(
+    def __init__(  # pylint: disable=too-many-arguments
         self,
         *,
         uuid: Optional[UUID] = None,
@@ -104,6 +108,7 @@ def __init__(
             properties=properties,
             read_perm=Attribute.NO_ACCESS,
             write_perm=write_perm,
+            max_length=buffer_size,
         )
 
     def bind(

adafruit_ble/services/nordic.py

@@ -43,12 +43,14 @@ class UARTService(Service):
     _server_tx = StreamOut(
         uuid=VendorUUID("6E400003-B5A3-F393-E0A9-E50E24DCCA9E"),
         timeout=1.0,
-        buffer_size=64,
+        # 512 is the largest negotiated MTU-3 value for all CircuitPython ports.
+        buffer_size=512,
     )
     _server_rx = StreamIn(
         uuid=VendorUUID("6E400002-B5A3-F393-E0A9-E50E24DCCA9E"),
         timeout=1.0,
-        buffer_size=64,
+        # 512 is the largest negotiated MTU-3 value for all CircuitPython ports.
+        buffer_size=512,
     )
 
     def __init__(self, service: Optional[_bleio.Service] = None) -> None: