adding CP example for PiCowbell

PiCowbell_CAN_Bus_Examples/CircuitPython_PiCowbell_CAN_Bus/code.py

@@ -0,0 +1,36 @@
+# SPDX-FileCopyrightText: Copyright (c) 2020 Bryan Siepert for Adafruit Industries
+#
+# SPDX-License-Identifier: MIT
+'''Simple Test for the PiCowbell CAN Bus with Raspberry Pi Pico'''
+
+from time import sleep
+import board
+import busio
+from digitalio import DigitalInOut
+from adafruit_mcp2515.canio import Message, RemoteTransmissionRequest
+from adafruit_mcp2515 import MCP2515 as CAN
+
+
+cs = DigitalInOut(board.GP20)
+cs.switch_to_output()
+spi = busio.SPI(board.GP18, board.GP19, board.GP16)
+
+can_bus = CAN(
+    spi, cs, loopback=True, silent=True
+)  # use loopback to test without another device
+while True:
+    with can_bus.listen(timeout=1.0) as listener:
+
+        message = Message(id=0x1234ABCD, data=b"adafruit", extended=True)
+        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))
+            if isinstance(msg, Message):
+                print("message data:", msg.data)
+            if isinstance(msg, RemoteTransmissionRequest):
+                print("RTR length:", msg.length)
+    sleep(1)