port/esp32: Add CAN(TWAI) class.

Signed-off-by: IhorNehrutsa <[email protected]>

docs/esp32/quickref.rst

@@ -651,6 +651,30 @@ users is encouraged.  Based on this feedback, the I2S class API and implementati
 
 ESP32 has two I2S buses with id=0 and id=1
 
+CAN bus
+-------
+
+See :ref:`machine.CAN <machine.CAN>` ::
+
+    The CAN driver is based on hardware implementation.
+    Any available output-capablepins can be used for TX, RX, BUS-OFF, and CLKOUT signal lines.
+
+.. image:: img/twai_blockdiag.png
+
+The driver is accessed via the :ref:`machine.CAN <machine.CAN>` class::
+
+    from machine import CAN
+    can = CAN(0, tx=5, rx=4, mode=CAN.NORMAL, baudrate=500000)
+    can.setfilter(0, CAN.FILTER_ADDRESS, [0x102])  # set a filter to receive messages with id = 0x102
+    can.send([1,2,3], 0x102)    # send a message with id 123
+    can.recv()                  # receive message
+
+    can.any()                   # returns True if there are any message to receive
+    can.info()                  # get information about the controller’s error states and TX and RX buffers
+    can.deinit()                # turn off the can bus
+    can.clear_rx_queue()        # clear messages in the FIFO
+    can.clear_tx_queue()        # clear messages in the transmit buffer
+
 Real time clock (RTC)
 ---------------------
 

examples/esp32_can.py

@@ -0,0 +1,73 @@
+from machine import CAN
+import time
+
+
+def send_and_check(can_bus, name, id, expected_result=True, extended=False):
+    can_bus.clear_tx_queue()
+    can_bus.clear_rx_queue()
+    can_bus.send([], id, extframe=extended)
+    time.sleep_ms(100)
+    if can_bus.any() == expected_result:
+        print("{}: OK".format(name))
+        if expected_result:
+            can_bus.recv()
+    else:
+        print("{}: FAILED".format(name))
+
+
+# 4 and 5 pins must be connected to each other, see documentation
+dev = CAN(
+    0, extframe=False, tx=5, rx=4, mode=CAN.SILENT_LOOPBACK, baudrate=50000, auto_restart=False
+)
+
+# Test send/receive message
+print("Loopback Test: no filter - STD")
+send_and_check(dev, "No filter", 0x100, True)
+
+# Set filter1
+print("Loopback Test: one filter - STD")
+dev.setfilter(0, CAN.FILTER_ADDRESS, [0x101, 0])
+send_and_check(dev, "Passing Message", 0x101, True)
+send_and_check(dev, "Blocked Message", 0x100, False)
+
+# Set filter2
+print("Loopback Test: second filter - STD")
+dev.setfilter(0, CAN.FILTER_ADDRESS, [0x102, 0])
+send_and_check(dev, "Passing Message - Bank 1", 0x102, True)
+send_and_check(dev, "Passing Message - Bank 0", 0x101, True)
+send_and_check(dev, "Blocked Message", 0x100, False)
+
+# Remove filter
+print("Loopback Test: clear filter - STD")
+dev.clearfilter()
+send_and_check(dev, "Passing Message - Bank 1", 0x102, True)
+send_and_check(dev, "Passing Message - Bank 0", 0x101, True)
+send_and_check(dev, "Passing any Message", 0x100, True)
+
+# Extended message tests
+# Move to Extended
+dev = CAN(
+    0,
+    extframe=True,
+    mode=CAN.SILENT_LOOPBACK,
+    baudrate=CAN.BAUDRATE_500k,
+    tx_io=18,
+    rx_io=19,
+    auto_restart=False,
+)
+
+# Test send/receive message
+print("Loopback Test: no filter - Extd")
+send_and_check(dev, "No filter", 0x100, True, extended=True)
+
+# Set filter1
+print("Loopback Test: one filter - Extd")
+dev.setfilter(0, CAN.FILTER_ADDRESS, [0x101, 0], extframe=True)
+send_and_check(dev, "Passing Message", 0x101, True, extended=True)
+send_and_check(dev, "Blocked Message", 0x100, False, extended=True)
+
+# Remove filter
+print("Loopback Test: clear filter - Extd")
+dev.clearfilter()
+send_and_check(dev, "Passing Message - Bank 0", 0x101, True, extended=True)
+send_and_check(dev, "Passing any Message", 0x100, True, extended=True)