Merge pull request #567 from shedfly/seeedstudio

Adding seeedstudio usb-can-analyzer interface

Author: felixdivo

can/interfaces/__init__.py

@@ -24,6 +24,7 @@
     "slcan": ("can.interfaces.slcan", "slcanBus"),
     "canalystii": ("can.interfaces.canalystii", "CANalystIIBus"),
     "systec": ("can.interfaces.systec", "UcanBus"),
+    "seeedstudio": ("can.interfaces.seeedstudio", "SeeedBus"),
 }
 
 BACKENDS.update(

can/interfaces/seeedstudio/__init__.py

@@ -0,0 +1,6 @@
+# coding: utf-8
+
+"""
+"""
+
+from can.interfaces.seeedstudio.seeedstudio import SeeedBus

can/interfaces/seeedstudio/seeedstudio.py

@@ -0,0 +1,270 @@
+# coding: utf-8
+
+"""
+To Support the Seeed USB-Can analyzer interface. The device will appear
+as a serial port, for example "/dev/ttyUSB0" on Linux machines
+or "COM1" on Windows.
+https://www.seeedstudio.com/USB-CAN-Analyzer-p-2888.html
+SKU 114991193
+"""
+
+import logging
+import struct
+from time import time
+from can import BusABC, Message
+
+logger = logging.getLogger("seeedbus")
+
+try:
+    import serial
+except ImportError:
+    logger.warning(
+        "You won't be able to use the serial can backend without "
+        "the serial module installed!"
+    )
+    serial = None
+
+
+class SeeedBus(BusABC):
+    """
+    Enable basic can communication over a USB-CAN-Analyzer device.
+    """
+
+    BITRATE = {
+        1000000: 0x01,
+        800000: 0x02,
+        500000: 0x03,
+        400000: 0x04,
+        250000: 0x05,
+        200000: 0x06,
+        125000: 0x07,
+        100000: 0x08,
+        50000: 0x09,
+        20000: 0x0A,
+        10000: 0x0B,
+        5000: 0x0C,
+    }
+
+    FRAMETYPE = {"STD": 0x01, "EXT": 0x02}
+
+    OPERATIONMODE = {
+        "normal": 0x00,
+        "loopback": 0x01,
+        "silent": 0x02,
+        "loopback_and_silent": 0x03,
+    }
+
+    def __init__(
+        self,
+        channel,
+        baudrate=2000000,
+        timeout=0.1,
+        frame_type="STD",
+        operation_mode="normal",
+        bitrate=500000,
+        *args,
+        **kwargs
+    ):
+        """
+        :param str channel:
+            The serial device to open. For example "/dev/ttyS1" or
+            "/dev/ttyUSB0" on Linux or "COM1" on Windows systems.
+
+        :param baudrate:
+            The default matches required baudrate
+
+        :param float timeout:
+            Timeout for the serial device in seconds (default 0.1).
+
+        :param str frame_type:
+            STD or EXT, to select standard or extended messages
+
+        :param operation_mode
+            normal, loopback, silent or loopback_and_silent.
+
+        :param bitrate
+            CAN bus bit rate, selected from available list.
+
+        """
+        self.bit_rate = bitrate
+        self.frame_type = frame_type
+        self.op_mode = operation_mode
+        self.filter_id = bytearray([0x00, 0x00, 0x00, 0x00])
+        self.mask_id = bytearray([0x00, 0x00, 0x00, 0x00])
+        if not channel:
+            raise ValueError("Must specify a serial port.")
+
+        self.channel_info = "Serial interface: " + channel
+        self.ser = serial.Serial(
+            channel, baudrate=baudrate, timeout=timeout, rtscts=False
+        )
+
+        super(SeeedBus, self).__init__(channel=channel, *args, **kwargs)
+        self.init_frame()
+
+    def shutdown(self):
+        """
+        Close the serial interface.
+        """
+        self.ser.close()
+
+    def init_frame(self, timeout=None):
+        """
+        Send init message to setup the device for comms. this is called during
+        interface creation.
+
+        :param timeout:
+            This parameter will be ignored. The timeout value of the channel is
+            used instead.
+        """
+        byte_msg = bytearray()
+        byte_msg.append(0xAA)  # Frame Start Byte 1
+        byte_msg.append(0x55)  # Frame Start Byte 2
+        byte_msg.append(0x12)  # Initialization Message ID
+        byte_msg.append(SeeedBus.BITRATE[self.bit_rate])  # CAN Baud Rate
+        byte_msg.append(SeeedBus.FRAMETYPE[self.frame_type])
+        byte_msg.extend(self.filter_id)
+        byte_msg.extend(self.mask_id)
+        byte_msg.append(SeeedBus.OPERATIONMODE[self.op_mode])
+        byte_msg.append(0x01)  # Follows 'Send once' in windows app.
+
+        byte_msg.extend([0x00] * 4)  # Manual bitrate config, details unknown.
+
+        crc = sum(byte_msg[2:]) & 0xFF
+        byte_msg.append(crc)
+
+        logger.debug("init_frm:\t%s", byte_msg.hex())
+        self.ser.write(byte_msg)
+
+    def flush_buffer(self):
+        self.ser.flushInput()
+
+    def status_frame(self, timeout=None):
+        """
+        Send status request message over the serial device.  The device will
+        respond but details of error codes are unknown but are logged - DEBUG.
+
+        :param timeout:
+            This parameter will be ignored. The timeout value of the channel is
+            used instead.
+        """
+        byte_msg = bytearray()
+        byte_msg.append(0xAA)  # Frame Start Byte 1
+        byte_msg.append(0x55)  # Frame Start Byte 2
+        byte_msg.append(0x04)  # Status Message ID
+        byte_msg.append(0x00)  # In response packet - Rx error count
+        byte_msg.append(0x00)  # In response packet - Tx error count
+
+        byte_msg.extend([0x00] * 14)
+
+        crc = sum(byte_msg[2:]) & 0xFF
+        byte_msg.append(crc)
+
+        logger.debug("status_frm:\t%s", byte_msg.hex())
+        self.ser.write(byte_msg)
+
+    def send(self, msg, timeout=None):
+        """
+        Send a message over the serial device.
+
+        :param can.Message msg:
+            Message to send.
+
+        :param timeout:
+            This parameter will be ignored. The timeout value of the channel is
+            used instead.
+        """
+
+        byte_msg = bytearray()
+        byte_msg.append(0xAA)
+
+        m_type = 0xC0
+        if msg.is_extended_id:
+            m_type += 1 << 5
+
+        if msg.is_remote_frame:
+            m_type += 1 << 4
+
+        m_type += msg.dlc
+        byte_msg.append(m_type)
+
+        if msg.is_extended_id:
+            a_id = struct.pack("<I", msg.arbitration_id)
+        else:
+            a_id = struct.pack("<H", msg.arbitration_id)
+
+        byte_msg.extend(a_id)
+        byte_msg.extend(msg.data)
+        byte_msg.append(0x55)
+
+        logger.debug("sending:\t%s", byte_msg.hex())
+        self.ser.write(byte_msg)
+
+    def _recv_internal(self, timeout):
+        """
+        Read a message from the serial device.
+
+        :param timeout:
+
+            .. warning::
+                This parameter will be ignored. The timeout value of the
+                channel is used.
+
+        :returns:
+            Received message and False (because not filtering as taken place).
+
+        :rtype:
+            can.Message, bool
+        """
+        try:
+            # ser.read can return an empty string
+            # or raise a SerialException
+            rx_byte_1 = self.ser.read()
+
+        except serial.SerialException:
+            return None, False
+
+        if rx_byte_1 and ord(rx_byte_1) == 0xAA:
+            rx_byte_2 = ord(self.ser.read())
+            time_stamp = time()
+            if rx_byte_2 == 0x55:
+                status = bytearray([0xAA, 0x55])
+                status += bytearray(self.ser.read(18))
+                logger.debug("status resp:\t%s", status.hex())
+
+            else:
+                length = int(rx_byte_2 & 0x0F)
+                is_extended = bool(rx_byte_2 & 0x20)
+                is_remote = bool(rx_byte_2 & 0x10)
+                if is_extended:
+                    s_3_4_5_6 = bytearray(self.ser.read(4))
+                    arb_id = (struct.unpack("<I", s_3_4_5_6))[0]
+
+                else:
+                    s_3_4 = bytearray(self.ser.read(2))
+                    arb_id = (struct.unpack("<H", s_3_4))[0]
+
+                data = bytearray(self.ser.read(length))
+                end_packet = ord(self.ser.read())
+                if end_packet == 0x55:
+                    msg = Message(
+                        timestamp=time_stamp,
+                        arbitration_id=arb_id,
+                        is_extended_id=is_extended,
+                        is_remote_frame=is_remote,
+                        dlc=length,
+                        data=data,
+                    )
+                    logger.debug("recv message: %s", str(msg))
+                    return msg, False
+
+                else:
+                    return None, False
+
+        return None, None
+
+    def fileno(self):
+        if hasattr(self.ser, "fileno"):
+            return self.ser.fileno()
+        # Return an invalid file descriptor on Windows
+        return -1

doc/interfaces/seeedstudio.rst

@@ -0,0 +1,85 @@
+.. _seeeddoc:
+
+
+USB-CAN Analyzer
+================
+...by Seeed Studio
+
+SKU: 114991193
+
+Links:
+
+- https://www.seeedstudio.com/USB-CAN-Analyzer-p-2888.html
+- https://github.com/SeeedDocument/USB-CAN_Analyzer
+- https://copperhilltech.com/blog/usbcan-analyzer-usb-to-can-bus-serial-protocol-definition/
+
+^^^^^^^^^^
+
+Installation
+------------
+This interface has additional dependencies which can be installed using pip and the optional extra [seeedstudio].  That will install an additional packages if not already available:
+ - pyserial
+
+
+::
+
+  pip3 install python-can[seeedstudio]
+
+
+^^^^^^^^^^
+
+
+Interface
+---------
+
+::
+
+    can.interfaces.seeedstudio.SeeedBus
+
+A bus example::
+
+    bus = can.interface.Bus(bustype='seeedstudio', channel='/dev/ttyUSB0', bitrate=500000)
+
+
+^^^^^^^^^^
+
+Parameters
+----------
+::
+
+ SeeedBus(channel,
+          baudrate=2000000,
+          timeout=0.1,
+          frame_type='STD',
+          operation_mode='normal',
+          bitrate=500000)
+
+ChANNEL
+ The serial port created by the USB device when connected.
+
+TIMEOUT
+ Only used by the underling serial port, it probably should not be changed.  The serial port baudrate=2000000 and rtscts=false are also matched to the device so are not added here.
+
+FRAMETYPE
+ - "STD"
+ - "EXT"
+
+OPERATIONMODE
+ - "normal"
+ - "loopback"
+ - "silent"
+ - "loopback_and_silent"
+
+BITRATE
+ - 1000000
+ - 800000
+ - 500000
+ - 400000
+ - 250000
+ - 200000
+ - 125000
+ - 100000
+ - 50000
+ - 20000
+ - 10000
+ - 5000

setup.py

@@ -25,6 +25,7 @@
 
 # Dependencies
 extras_require = {
+    "seeedstudio": ["pyserial>=3.0"],
     "serial": ["pyserial~=3.0"],
     "neovi": ["python-ics>=2.12", "filelock"],
 }