intf: add support for RTT interface

pyproject.toml

@@ -13,6 +13,7 @@ requires-python = ">=3.10"
 dependencies = [
          "pyserial>=3.5",
          "crcmod>=1.7",
+         "pylink-square>=1.2",
 ]
 classifiers = [
   "Development Status :: 4 - Beta",

src/nxslib/intf/rtt.py

@@ -0,0 +1,116 @@
+"""Module containing the NxScope RTT interface implementation."""
+
+import time
+
+import pylink  # type: ignore
+
+from nxslib.intf.iintf import ICommInterface
+from nxslib.logger import logger
+
+###############################################################################
+# Class: RTTDevice
+###############################################################################
+
+
+class RTTDevice(ICommInterface):  # pragma: no cover
+    """A class used to represent a serial port interface."""
+
+    def __init__(
+        self,
+        target_device: str,
+        buffer_index: int,
+        upsize: int,
+        interface: str,
+        blockaddr: str = "auto",
+    ) -> None:
+        """Intitialize a serial interface.
+
+        :param : target_device: target chip name
+        :param : buffer_index: nxscope RTT buffer index
+        :param : upsize: nxscope RTT buffer size
+        :param : interface: JLink interface: swd or jtag
+        :param : blockaddr: RTT block address as hex or `auto`
+        """
+        # ger RTT block address
+        if blockaddr != "auto":
+            block_address = int(blockaddr, 16)
+            print("RTT block address = ", hex(block_address))
+        else:
+            block_address = None
+            print("Auto-search for RTT block address")
+
+        # get JLink interface
+        if interface in ["swd", "SWD"]:
+            jlinkinterface = pylink.enums.JLinkInterfaces.SWD
+            print("JLink interface is SWD")
+        elif interface in ["jtag", "JTAG"]:
+            jlinkinterface = pylink.enums.JLinkInterfaces.JTAG
+            print("JLink interface is JTAG")
+        else:
+            raise ValueError
+
+        self.buffer_index = buffer_index
+        self.upsize = upsize
+
+        # connect to JLink
+        while True:
+            try:
+                print("connecting to", target_device, "...")
+                self._jlink = pylink.JLink()
+                self._jlink.open()
+                self._jlink.set_tif(jlinkinterface)
+                self._jlink.connect(target_device)
+                print("connected, starting RTT...")
+                self._jlink.rtt_start(block_address)
+                break
+            except pylink.errors.JLinkException:
+                time.sleep(0.1)
+
+        # wait for RTT (revisit: do we need that ?)
+        while True:
+            try:
+                num_up = self._jlink.rtt_get_num_up_buffers()
+                num_down = self._jlink.rtt_get_num_down_buffers()
+                print(
+                    "RTT started, %d up bufs, %d down bufs."
+                    % (num_up, num_down)
+                )
+                break
+            except pylink.errors.JLinkRTTException:
+                time.sleep(0.1)
+
+        super().__init__()
+
+    def __del__(self) -> None:
+        """Make sure that serial port is closed."""
+
+    def start(self) -> None:
+        """Start the interface."""
+        logger.debug("start RTT interface")
+
+    def stop(self) -> None:
+        """Stop the interface."""
+        logger.debug("Stop RTT interface")
+
+    def drop_all(self) -> None:
+        """Drop all frames."""
+        for _ in range(10):
+            self._read()
+
+    def _read(self) -> bytes:
+        """Interface specific read method."""
+        assert self._jlink
+        try:
+            _bytes = self._jlink.rtt_read(self.buffer_index, self.upsize)
+            return bytes(_bytes)
+        except Exception as exc:
+            logger.debug("pylink exception ignored: %s", str(exc))
+            return b""
+
+    def _write(self, data: bytes) -> None:
+        """Interface specific write method.
+
+        :param data: bytes to send
+        """
+        assert self._jlink
+        self._jlink.rtt_write(self.buffer_index, data)

tests/intf/test_rtt.py

@@ -0,0 +1,8 @@
+import pytest  # type: ignore
+
+from nxslib.intf.rtt import RTTDevice
+
+
+def test_nxslibserial_init():
+    with pytest.raises(ValueError):
+        _ = RTTDevice("test", 1, 100, "x")