From d5eb6474ca2cba7b48b105a93af1e94d48dd73a1 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lasse=20Fr=C3=B6hner?= <lasse@starcopter.com>
Date: Thu, 24 Jul 2025 14:03:39 +0200
Subject: [PATCH 1/4] Fix bitrate calculation for PCAN interfaces

---
 .../can/media/pythoncan/_pythoncan.py         | 29 ++++++-------------
 1 file changed, 9 insertions(+), 20 deletions(-)

diff --git a/pycyphal/transport/can/media/pythoncan/_pythoncan.py b/pycyphal/transport/can/media/pythoncan/_pythoncan.py
index 28f0ce6f..584fdf26 100644
--- a/pycyphal/transport/can/media/pythoncan/_pythoncan.py
+++ b/pycyphal/transport/can/media/pythoncan/_pythoncan.py
@@ -491,32 +491,21 @@ def _construct_pcan(parameters: _InterfaceParameters) -> can.ThreadSafeBus:
     if isinstance(parameters, _FDInterfaceParameters):
         if parameters.bitrate[0] == 0 or parameters.bitrate[1] == 0:
             raise InvalidMediaConfigurationError("Bitrate must be non-zero")
-        # These magic numbers come from the settings of PCAN adapter.
-        # They don't allow any direct baudrate settings, you have to set all lengths and value of the main frequency.
-        # Bit lengths below are very universal and can be applied for almost every popular baudrate.
-        # There is probably a better solution here, but it needs significantly more time to implement it.
-        f_clock = 40000000
-        nom_tseg1, nom_tseg2, nom_sjw = 3, 1, 1
-        data_tseg1, data_tseg2, data_sjw = 3, 1, 1
-
-        nom_br = int(f_clock / parameters.bitrate[0] / (nom_tseg1 + nom_tseg2 + nom_sjw))
-        data_br = int(f_clock / parameters.bitrate[1] / (data_tseg1 + data_tseg2 + data_sjw))
-        # TODO: validate the result and see if it is within an acceptable range
 
+        timing = can.BitTimingFd.from_sample_point(
+            f_clock=80_000_000,  # TODO: 80 MHz is a good choice for high data rates, what about lower ones?
+            nom_bitrate=parameters.bitrate[0],
+            nom_sample_point=87.5,
+            data_bitrate=parameters.bitrate[1],
+            data_sample_point=87.5,
+        )
+        _logger.debug("PCAN timing solution: %s", timing)
         return (
             PythonCANBusOptions(),
             can.ThreadSafeBus(
                 interface=parameters.interface_name,
                 channel=parameters.channel_name,
-                f_clock=f_clock,
-                nom_brp=nom_br,
-                data_brp=data_br,
-                nom_tseg1=nom_tseg1,
-                nom_tseg2=nom_tseg2,
-                nom_sjw=nom_sjw,
-                data_tseg1=data_tseg1,
-                data_tseg2=data_tseg2,
-                data_sjw=data_sjw,
+                timing=timing,
                 fd=True,
             ),
         )

From 78bdf3d8d6dd08341e6fb8a3df4d788b009b6244 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lasse=20Fr=C3=B6hner?= <lasse@starcopter.com>
Date: Mon, 28 Jul 2025 10:26:59 +0200
Subject: [PATCH 2/4] Fix CAN FD bitrate switching

Set the BRS bit for pythoncan transports when the interface operates in CAN FD mode.

Fixes https://github.com/OpenCyphal/pycyphal/issues/368
---
 pycyphal/transport/can/media/pythoncan/_pythoncan.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/pycyphal/transport/can/media/pythoncan/_pythoncan.py b/pycyphal/transport/can/media/pythoncan/_pythoncan.py
index 584fdf26..a62eb2cd 100644
--- a/pycyphal/transport/can/media/pythoncan/_pythoncan.py
+++ b/pycyphal/transport/can/media/pythoncan/_pythoncan.py
@@ -300,6 +300,7 @@ async def send(self, frames: typing.Iterable[Envelope], monotonic_deadline: floa
                 is_extended_id=(f.frame.format == FrameFormat.EXTENDED),
                 data=f.frame.data,
                 is_fd=self._is_fd,
+                bitrate_switch=self._is_fd,
             )
             try:
                 desired_timeout = monotonic_deadline - loop.time()

From 36bee2bde674368b2460aa70e9888ca4e37594a2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lasse=20Fr=C3=B6hner?= <lasse@starcopter.com>
Date: Mon, 4 Aug 2025 08:24:23 +0200
Subject: [PATCH 3/4] Bump patch version to 1.24.4

---
 pycyphal/_version.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pycyphal/_version.py b/pycyphal/_version.py
index 1a569d73..d0702e5a 100644
--- a/pycyphal/_version.py
+++ b/pycyphal/_version.py
@@ -1 +1 @@
-__version__ = "1.24.3"
+__version__ = "1.24.4"

From aa1b0884ff5524b58115aea7dcbb165a98cba66e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Lasse=20Fr=C3=B6hner?= <lasse@starcopter.com>
Date: Mon, 4 Aug 2025 09:23:03 +0200
Subject: [PATCH 4/4] Set sample point location to 80%

---
 pycyphal/transport/can/media/pythoncan/_pythoncan.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pycyphal/transport/can/media/pythoncan/_pythoncan.py b/pycyphal/transport/can/media/pythoncan/_pythoncan.py
index a62eb2cd..21b5c7d9 100644
--- a/pycyphal/transport/can/media/pythoncan/_pythoncan.py
+++ b/pycyphal/transport/can/media/pythoncan/_pythoncan.py
@@ -496,9 +496,9 @@ def _construct_pcan(parameters: _InterfaceParameters) -> can.ThreadSafeBus:
         timing = can.BitTimingFd.from_sample_point(
             f_clock=80_000_000,  # TODO: 80 MHz is a good choice for high data rates, what about lower ones?
             nom_bitrate=parameters.bitrate[0],
-            nom_sample_point=87.5,
+            nom_sample_point=80,
             data_bitrate=parameters.bitrate[1],
-            data_sample_point=87.5,
+            data_sample_point=80,
         )
         _logger.debug("PCAN timing solution: %s", timing)
         return (