tweaks, fixed docs

Author: siddacious

adafruit_mcp2515/__init__.py

@@ -209,24 +209,7 @@ def _tx_buffer_status_decode(status_byte):
 
 
 class MCP2515:  # pylint:disable=too-many-instance-attributes
-    """
-    A common shared-bus protocol.
-
-    :param ~busio.SPI spi: The SPI bus used to communicate with the MCP2515
-    :param ~digitalio.DigitalInOut cs_pin:  SPI bus enable pin
-    :param int baudrate: The bit rate of the bus in Hz, using a 16Mhz crystal. All devices on\
-        the bus must agree on this value. Defaults to 250000.
-    :param bool loopback: Receive only packets sent from this device, and send only to\
-        this device. Requires that `silent` is also set to `False`, but only prevents\
-        transimssion to other devices. Otherwise the send/receive behavior is normal.
-    :param bool silent:When `True` the controller does not transmit and all messages\
-        are received, ignoring errors and filters. This mode can be used to “sniff” a CAN\
-        bus without interfering. Defaults to `False`.
-    :param bool auto_restart: **Not supported by hardware. An `AttributeError`
-        will be raised if `auto_restart` is set to `True`** If `True`, will restart\
-        communications after entering bus-off state. Defaults to `False`.
-    :param bool debug: If `True`, will enable printing debug information. Defaults to `False`.
-    """
+    """A common shared-bus protocol."""
 
     def __init__(
         self,
@@ -239,6 +222,18 @@ def __init__(
         auto_restart: bool = False,
         debug: bool = False
     ):
+        """A common shared-bus protocol.
+        :param ~busio.SPI spi: The SPI bus used to communicate with the MCP2515
+        :param ~digitalio.DigitalInOut cs_pin:  SPI bus enable pin
+        :param int baudrate: The bit rate of the bus in Hz, using a 16Mhz crystal. All devices on the bus must agree on this value. Defaults to 250000.
+        :param bool loopback: Receive only packets sent from this device, and send only to this device. Requires that `silent` is also set to `False`, but only prevents transmission to other devices. Otherwise the send/receive behavior is normal.
+        :param bool silent: When `True` the controller does not transmit and all messages are received, ignoring errors and filters. This mode can be used to “sniff” a CAN bus without interfering. Defaults to `False`.
+        :param bool auto_restart: **Not supported by hardware. An `AttributeError` will be raised if `auto_restart` is set to `True`**
+
+            If `True`, will restart\ communications after entering bus-off state. Defaults to `False`.
+
+        :param bool debug: If `True`, will enable printing debug information. Defaults to `False`.
+        """
 
         if loopback and not silent:
             raise AttributeError("Loopback mode requires silent to be set")
@@ -329,7 +324,7 @@ def initialize(self):
 
         self._set_mode(new_mode)
 
-    def send(self, message_obj, wait_sent=True):
+    def send(self, message_obj):
         """Send a message on the bus with the given data and id. If the message could not be sent
          due to a full fifo or a bus error condition, RuntimeError is raised.
 
@@ -339,24 +334,10 @@ def send(self, message_obj, wait_sent=True):
 
         # TODO: Timeout
         tx_buff = self._get_tx_buffer()  # info = addr.
+        if tx_buff is None:
+            raise RuntimeError("No transmit buffer available to send")
 
-        # TODO: set buffer priority
-        self._write_message(tx_buff, message_obj)
-        if not wait_sent:
-            return True
-        sleep(0.010)
-
-        send_confirmed = False
-        self._timer.rewind_to(0.005)
-        while not self._timer.expired:
-            # the status register address is whatever tx_buff_n is, minus one?
-            tx_buff_status = self._read_register(tx_buff.CTRL_REG)
-            self._dbg(_tx_buffer_status_decode(tx_buff_status))
-            send_confirmed = (tx_buff_status & _TXB_TXREQ_M) == 0
-            if send_confirmed:
-                return True
-
-        raise RuntimeError("Timeout occurred waiting for transmit confirmation")
+        return self._write_message(tx_buff, message_obj)
 
     @property
     def unread_message_count(self):
@@ -433,6 +414,8 @@ def _read_from_rx_buffers(self):
 
     def _write_message(self, tx_buffer, message_obj):
 
+        if tx_buffer is None:
+            raise RuntimeError("No transmit buffer available to send")
         if isinstance(message_obj, RemoteTransmissionRequest):
             dlc = message_obj.length
         else:
@@ -477,6 +460,7 @@ def _write_message(self, tx_buffer, message_obj):
 
         # send the frame based on the current buffers
         self._start_transmit(tx_buffer)
+        return True
 
     # TODO: Priority
     def _start_transmit(self, tx_buffer):

examples/mcp2515_receive.py

@@ -2,48 +2,39 @@
 #
 # SPDX-License-Identifier: MIT
 
-# import board
-# import busio
-# import digitalio
-# import adafruit_mcp2515
-# from adafruit_mcp2515.canio import Timer
-
-
-from digitalio import DigitalInOut
-from board import D5 as CS_PIN, SPI
+import digitalio
+import board
+import busio
 from adafruit_mcp2515.canio import Timer
+from adafruit_mcp2515.canio import RemoteTransmissionRequest, Message
 from adafruit_mcp2515 import MCP2515 as CAN
 
-# from board import CAN_RX, CAN_TX
-
-
-def bus():
-    cs = DigitalInOut(CS_PIN)
-    cs.switch_to_output()
-    return CAN(SPI(), cs)
-
-
-# cs = digitalio.DigitalInOut(board.D5)
-# cs.direction = digitalio.Direction.OUTPUT
-# spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
-# can = adafruit_mcp2515.MCP2515(spi, cs)
+cs = digitalio.DigitalInOut(board.D5)
+cs.switch_to_output()
+spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
+mcp = CAN(spi, cs)
 
 t = Timer(timeout=5)
+
 while True:
-    with bus() as can, can.listen(timeout=1.0) as listener:
+    # print occationally to show we're alive
+    if t.expired:
+        print(".", end="")
+        t.rewind_to(1)
+    with mcp.listen(timeout=1.0) as listener:
         message_count = listener.in_waiting()
-        print(message_count, "messages available")
+
         if message_count == 0:
             continue
         for _i in range(message_count):
+            print(message_count, "messages available")
             msg = listener.receive()
             print("Message received from ", hex(msg.id))
-            print("message data:", msg.data)
-            message_str = "::".join(["0x{:02X}".format(i) for i in msg.data])
-            print(message_str)
-            print("RTR:", msg.rtr)
+            if isinstance(msg, Message):
+                print("Message data:", msg.data)
+                message_str = "::".join(["0x{:02X}".format(i) for i in msg.data])
+                print(message_str)
+
+            if isinstance(msg, RemoteTransmissionRequest):
+                print("RTR length:", msg.length)
             print("")
-        # instead of sleeping, pool for messages to fill queue
-        t.rewind_to(5)
-        while not t.expired:
-            message_count = listener.in_waiting()

examples/mcp2515_send_and_receive.py

@@ -0,0 +1,34 @@
+# SPDX-FileCopyrightText: Copyright (c) 2020 Bryan Siepert for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+import board
+import busio
+from digitalio import DigitalInOut
+from adafruit_mcp2515.canio import Message, RemoteTransmissionRequest
+from adafruit_mcp2515 import MCP2515 as CAN
+
+NODE_ID = 0x1234ABCD
+
+cs = DigitalInOut(board.D5)
+cs.switch_to_output()
+spi = busio.SPI(board.SCK, board.MOSI, board.MISO)
+
+can_bus = CAN(spi, cs)
+while True:
+    with can_bus.listen(timeout=1.0) as listener:
+
+        message = Message(id=NODE_ID, data=b"adafruit", extended=True)
+        send_success = can_bus.send(message)
+        print("Send success:", send_success)
+        message_count = listener.in_waiting()
+        if message_count == 0:
+            continue
+        print(message_count, "messages available")
+        for _i in range(message_count):
+            msg = listener.receive()
+            print("Message from ", hex(msg.id), "extended:", msg.extended)
+            if isinstance(msg, Message):
+                print("message data:", msg.data)
+            if isinstance(msg, RemoteTransmissionRequest):
+                print("RTR length:", msg.length)
+            print("")

examples/mcp2515_simpletest.py

@@ -5,7 +5,7 @@
 import board
 import busio
 from digitalio import DigitalInOut
-from adafruit_mcp2515.canio import Message
+from adafruit_mcp2515.canio import Message, RemoteTransmissionRequest
 from adafruit_mcp2515 import MCP2515 as CAN
 
 
@@ -20,12 +20,15 @@
     with can_bus.listen(timeout=1.0) as listener:
 
         message = Message(id=0x1234ABCD, data=b"adafruit", extended=True)
-        can_bus.send(message)
+        send_success = can_bus.send(message)
+        print("Send success:", send_success)
         message_count = listener.in_waiting()
         print(message_count, "messages available")
         for _i in range(message_count):
             msg = listener.receive()
             print("Message from ", hex(msg.id))
-            print("message data:", msg.data)
-            print("")
+            if isinstance(msg, Message):
+                print("message data:", msg.data)
+            if isinstance(msg, RemoteTransmissionRequest):
+                print("RTR length:", msg.length)
     sleep(1)