From bdf405dfcf7349943cd0d5b6c80430317efb2f15 Mon Sep 17 00:00:00 2001
From: Marcell Nagy <marcell.nagy@diamond.ac.uk>
Date: Mon, 13 May 2024 11:08:46 +0100
Subject: [PATCH] Add serial connection

---
 pyproject.toml                              |  7 +--
 src/fastcs/connections/serial_connection.py | 54 +++++++++++++++++++++
 2 files changed, 55 insertions(+), 6 deletions(-)
 create mode 100644 src/fastcs/connections/serial_connection.py

diff --git a/pyproject.toml b/pyproject.toml
index 4ab1226c..012c367c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -10,12 +10,7 @@ classifiers = [
     "Programming Language :: Python :: 3.11",
 ]
 description = "Control system agnostic framework for building Device support in Python that will work for both EPICS and Tango"
-dependencies = [
-    "numpy",
-    "pydantic",
-    "pvi~=0.8.1",
-    "softioc",
-]
+dependencies = ["aioserial", "numpy", "pydantic", "pvi~=0.8.1", "softioc"]
 dynamic = ["version"]
 license.file = "LICENSE"
 readme = "README.md"
diff --git a/src/fastcs/connections/serial_connection.py b/src/fastcs/connections/serial_connection.py
new file mode 100644
index 00000000..f62b15d8
--- /dev/null
+++ b/src/fastcs/connections/serial_connection.py
@@ -0,0 +1,54 @@
+import asyncio
+from dataclasses import dataclass
+
+import aioserial
+
+
+class NotOpenedError(Exception):
+    pass
+
+
+@dataclass
+class SerialConnectionSettings:
+    port: str
+    baud: int = 115200
+
+
+class SerialConnection:
+    def __init__(self):
+        self.aioserial_instance = None
+        self._lock = asyncio.Lock()
+
+    async def connect(self, settings: SerialConnectionSettings) -> None:
+        self.aioserial_instance = aioserial.AioSerial(
+            port=settings.port, baudrate=settings.baud
+        )
+
+    def ensure_open(self):
+        if self.aioserial_instance is None:
+            raise NotOpenedError(
+                "Need to call connect() before using SerialConnection."
+            )
+
+    async def send_command(self, message: bytes) -> None:
+        async with self._lock:
+            self.ensure_open()
+            await self._send_message(message)
+
+    async def send_query(self, message: bytes, response_size: int) -> bytes:
+        async with self._lock:
+            self.ensure_open()
+            await self._send_message(message)
+            return await self._receive_response(response_size)
+
+    async def close(self) -> None:
+        async with self._lock:
+            self.ensure_open()
+            self.aioserial_instance.close()
+            self.aioserial_instance = None
+
+    async def _send_message(self, message):
+        await self.aioserial_instance.write_async(message)
+
+    async def _receive_response(self, size):
+        return await self.aioserial_instance.read_async(size)