CAN

Example

Use ESP32 internal CAN controller resources to realize CAN bus data sending and receiving, Note: Before using, you need to access CAN UNIT for the device.

from m5stack import *
from m5ui import *
from uiflow import *
from machine import CAN
import time

setScreenColor(0x222222)

frame = None

label0 = M5TextBox(16, 53, "Device State: ", lcd.FONT_Default, 0x00ff7c, rotate=0)
label1 = M5TextBox(126, 53, "Text", lcd.FONT_Default, 0xFFFFFF, rotate=0)
label2 = M5TextBox(16, 97, "message: ", lcd.FONT_Default, 0x00ff7c, rotate=0)
label3 = M5TextBox(16, 132, "Text", lcd.FONT_Default, 0xFFFFFF, rotate=0)
label4 = M5TextBox(16, 162, "Text", lcd.FONT_Default, 0xFFFFFF, rotate=0)
label5 = M5TextBox(16, 192, "Text", lcd.FONT_Default, 0xFFFFFF, rotate=0)

def buttonA_wasPressed():
  global frame
  can.send([0, 1, 2, 3, 4, 5, 6, 7], 0)
  pass
btnA.wasPressed(buttonA_wasPressed)

def buttonB_wasPressed():
  global frame
  can.clear_tx_queue()
  can.clear_rx_queue()
  pass
btnB.wasPressed(buttonB_wasPressed)

def buttonC_wasPressed():
  global frame
  can.restart()
  pass
btnC.wasPressed(buttonC_wasPressed)


can = CAN(0, extframe=True, mode=CAN.NORMAL, baudrate=CAN.BAUDRATE_25K, tx_io=17, rx_io=16, auto_restart=False)
while True:
  label1.setText(str(can.state()))
  if can.any():
    frame = can.recv()
    label3.setText(str(frame[0]))
    label4.setText(str(frame[1]))
    label5.setText(str(frame[3]))
  wait_ms(30)
  wait_ms(2)

API

from machine import CAN
can = CAN(0, extframe=True, mode=CAN.NORMAL, baudrate=CAN.BAUDRATE_25K, tx_io=17, rx_io=16, auto_restart=False)

• Initialize CAN bus, configure frame expansion mode, operating mode (normal mode, loopback mode, etc.) and baud rate setting.

can.any()

• Check for unread data in FIFOs

frame = can.recv()

• receive data

can.send([0, 1, 2, 3, 4, 5, 6, 7], id)

• Sends a piece of data and specifies the ID of the data frame, the ID length is 1 byte, the incoming data type is required to be list or tuple, and the data length of the data frame is required to be 8 bytes.

can.setfilter(0, CAN.FILTER_RAW_SINGLE, [])

• Setting up filter groups

can.state()

• Get CAN controller status

can.clear_rx_queue()

• Clear the receive queue

can.clear_tx_queue()

• Clearing the send queue

can.clearfilter()

• Clear Filter Groups

can.restart()

• Reboot CAN bus

can.deinit()

• Stop CAN bus