57 lines
1.8 KiB
Python
57 lines
1.8 KiB
Python
import struct
|
|
import time
|
|
|
|
import board
|
|
import canio
|
|
import digitalio
|
|
|
|
# If the CAN transceiver has a standby pin, bring it out of standby mode
|
|
if hasattr(board, 'CAN_STANDBY'):
|
|
standby = digitalio.DigitalInOut(board.CAN_STANDBY)
|
|
standby.switch_to_output(False)
|
|
|
|
# If the CAN transceiver is powered by a boost converter, turn on its supply
|
|
if hasattr(board, 'BOOST_ENABLE'):
|
|
boost_enable = digitalio.DigitalInOut(board.BOOST_ENABLE)
|
|
boost_enable.switch_to_output(True)
|
|
|
|
# Use this line if your board has dedicated CAN pins. (Feather M4 CAN and Feather STM32F405)
|
|
can = canio.CAN(rx=board.CAN_RX, tx=board.CAN_TX, baudrate=250_000, auto_restart=True)
|
|
# On ESP32S2 most pins can be used for CAN. Uncomment the following line to use IO5 and IO6
|
|
#can = canio.CAN(rx=board.IO6, tx=board.IO5, baudrate=250_000, auto_restart=True)
|
|
listener = can.listen(matches=[canio.Match(0x409)], timeout=.1)
|
|
|
|
old_bus_state = None
|
|
count = 0
|
|
|
|
while True:
|
|
bus_state = can.state
|
|
if bus_state != old_bus_state:
|
|
print(f"Bus state changed to {bus_state}")
|
|
old_bus_state = bus_state
|
|
|
|
now_ms = (time.monotonic_ns() // 1_000_000) & 0xffffffff
|
|
print(f"Sending message: count={count} now_ms={now_ms}")
|
|
|
|
message = canio.Message(id=0x408, data=struct.pack("<II", count, now_ms))
|
|
while True:
|
|
can.send(message)
|
|
|
|
message_in = listener.receive()
|
|
if message_in is None:
|
|
print("No ACK received within timeout")
|
|
continue
|
|
|
|
data = message_in.data
|
|
if len(data) != 4:
|
|
print(f"Unusual message length {len(data)}")
|
|
continue
|
|
|
|
ack_count = struct.unpack("<I", data)[0]
|
|
if ack_count == count:
|
|
print("Received ACK")
|
|
break
|
|
print(f"Received incorrect ACK: {ack_count} should be {count}")
|
|
|
|
time.sleep(.5)
|
|
count += 1
|