.. _canopen-sample:
CANopen
#######
Overview
********
This sample application shows how the `CANopenNode`_ CANopen protocol
stack can be used in Zephyr.
CANopen is an internationally standardized (`EN 50325-4`_, `CiA 301`_)
communication protocol and device specification for embedded
systems used in automation. CANopenNode is a 3rd party, open-source
CANopen protocol stack.
Apart from the CANopen protocol stack integration, this sample also
demonstrates the use of non-volatile storage for the CANopen object
dictionary.
Requirements
************
* A board with CAN bus and flash support
* Host PC with CAN bus support
Building and Running
********************
Building and Running for TWR-KE18F
==================================
The :ref:`twr_ke18f` board is equipped with an onboard CAN
transceiver. This board supports CANopen LED indicators (red and green
LEDs). The sample can be built and executed for the TWR-KE18F as
follows:
.. zephyr-app-commands::
:zephyr-app: samples/subsys/canbus/canopen
:board: twr_ke18f
:goals: build flash
:compact:
Pressing the button labelled ``SW3`` will increment the button press
counter object at index ``0x2102`` in the object dictionary.
Building and Running for FRDM-K64F
==================================
The :ref:`frdm_k64f` board does not come with an onboard CAN
transceiver. In order to use the CAN bus on the FRDM-K64F board, an
external CAN bus tranceiver must be connected to ``PTB18``
(``CAN0_TX``) and ``PTB19`` (``CAN0_RX``). This board supports CANopen
LED indicators (red and green LEDs)
The sample can be built and executed for the FRDM-K64F as follows:
.. zephyr-app-commands::
:zephyr-app: samples/subsys/canbus/canopen
:board: frdm_k64f
:goals: build flash
:compact:
Pressing the button labelled ``SW3`` will increment the button press
counter object at index ``0x2102`` in the object dictionary.
Testing CANopen Communication
*****************************
CANopen communication between the host PC and Zephyr can be
established using any CANopen compliant application on the host PC.
The examples here uses `CANopen for Python`_ for communicating between
the host PC and Zephyr. First, install python-canopen along with the
python-can backend as follows:
.. code-block:: console
pip3 install --user canopen python-can
Next, bring up the CAN interface on the test PC. On GNU/Linux, this
can be done as follows:
.. code-block:: console
sudo ip link set can0 type can bitrate 125000 restart-ms 100
sudo ip link set up can0
To better understand the communication taking place in the following
examples, you can monitor the CAN traffic from the host PC. On
GNU/Linux, this can be accomplished using ``candump`` from the
`can-utils`_ package as follows:
.. code-block:: console
candump can0
NMT State Changes
=================
Changing the Network Management (NMT) state of the node can be
accomplished using the following Python code:
.. code-block:: py
import canopen
import os
import time
ZEPHYR_BASE = os.environ['ZEPHYR_BASE']
EDS = os.path.join(ZEPHYR_BASE, 'samples', 'subsys', 'canbus', 'canopen',
'objdict', 'objdict.eds')
NODEID = 10
network = canopen.Network()
# 'can0' and 'socketcan' is for GNU/Linux, please see the python-can documentation for other platforms:
network.connect(channel='can0', bustype='socketcan')
node = network.add_node(NODEID, EDS)
# Green indicator LED will flash slowly
node.nmt.state = 'STOPPED'
time.sleep(5)
# Green indicator LED will flash faster
node.nmt.state = 'PRE-OPERATIONAL'
time.sleep(5)
# Green indicator LED will be steady on
node.nmt.state = 'OPERATIONAL'
time.sleep(5)
# Node will reset communication
node.nmt.state = 'RESET COMMUNICATION'
node.nmt.wait_for_heartbeat()
# Node will reset
node.nmt.state = 'RESET'
node.nmt.wait_for_heartbeat()
network.disconnect()
Running the above Python code will update the NMT state of the node
which is reflected on the indicator LEDs (if present).
SDO Upload
==========
Reading a Service Data Object (SDO) at a given index of the CANopen
object dictionary (here index ``0x1008``, the manufacturer device
name) can be accomplished using the following Python code:
.. code-block:: py
import canopen
import os
ZEPHYR_BASE = os.environ['ZEPHYR_BASE']
EDS = os.path.join(ZEPHYR_BASE, 'samples', 'subsys', 'canbus', 'canopen',
'objdict', 'objdict.eds')
NODEID = 10
network = canopen.Network()
# 'can0' and 'socketcan' is for GNU/Linux, please see the python-can documentation for other platforms:
network.connect(channel='can0', bustype='socketcan')
node = network.add_node(NODEID, EDS)
name = node.sdo['Manufacturer device name']
print("Device name: '{}'".format(name.raw))
network.disconnect()
Running the above Python code should produce the following output:
.. code-block:: console
Device name: 'Zephyr RTOS/CANopenNode'
SDO Download
============
Writing to a Service Data Object (SDO) at a given index of the CANopen
object dictionary (here index ``0x1017``, the producer heartbeat time)
can be accomplished using the following Python code:
.. code-block:: py
import canopen
import os
ZEPHYR_BASE = os.environ['ZEPHYR_BASE']
EDS = os.path.join(ZEPHYR_BASE, 'samples', 'subsys', 'canbus', 'canopen',
'objdict', 'objdict.eds')
NODEID = 10
network = canopen.Network()
# 'can0' and 'socketcan' is for GNU/Linux, please see the python-can documentation for other platforms:
network.connect(channel='can0', bustype='socketcan')
node = network.add_node(NODEID, EDS)
heartbeat = node.sdo['Producer heartbeat time']
reboots = node.sdo['Power-on counter']
# Set heartbeat interval without saving to non-volatile storage
print("Initial heartbeat time: {} ms".format(heartbeat.raw))
print("Power-on counter: {}".format(reboots.raw))
heartbeat.raw = 5000
print("Updated heartbeat time: {} ms".format(heartbeat.raw))
# Reset and read heartbeat interval again
node.nmt.state = 'RESET'
node.nmt.wait_for_heartbeat()
print("heartbeat time after reset: {} ms".format(heartbeat.raw))
print("Power-on counter: {}".format(reboots.raw))
# Set interval and store it to non-volatile storage
heartbeat.raw = 2000
print("Updated heartbeat time: {} ms".format(heartbeat.raw))
node.store()
# Reset and read heartbeat interval again
node.nmt.state = 'RESET'
node.nmt.wait_for_heartbeat()
print("heartbeat time after store and reset: {} ms".format(heartbeat.raw))
print("Power-on counter: {}".format(reboots.raw))
# Restore default values, reset and read again
node.restore()
node.nmt.state = 'RESET'
node.nmt.wait_for_heartbeat()
print("heartbeat time after restore and reset: {} ms".format(heartbeat.raw))
print("Power-on counter: {}".format(reboots.raw))
network.disconnect()
Running the above Python code should produce the following output:
.. code-block:: console
Initial heartbeat time: 1000 ms
Power-on counter: 1
Updated heartbeat time: 5000 ms
heartbeat time after reset: 1000 ms
Power-on counter: 2
Updated heartbeat time: 2000 ms
heartbeat time after store and reset: 2000 ms
Power-on counter: 3
heartbeat time after restore and reset: 1000 ms
Power-on counter: 4
Note that the power-on counter value may be different.
PDO Mapping
===========
Transmit Process Data Object (PDO) mapping for data at a given index
of the CANopen object dictionary (here index ``0x2102``, the button
press counter) can be accomplished using the following Python code:
.. code-block:: py
import canopen
import os
ZEPHYR_BASE = os.environ['ZEPHYR_BASE']
EDS = os.path.join(ZEPHYR_BASE, 'samples', 'subsys', 'canbus', 'canopen',
'objdict', 'objdict.eds')
NODEID = 10
network = canopen.Network()
# 'can0' and 'socketcan' is for GNU/Linux, please see the python-can documentation for other platforms:
network.connect(channel='can0', bustype='socketcan')
node = network.add_node(NODEID, EDS)
button = node.sdo['Button press counter']
# Read current TPDO mapping
node.tpdo.read()
# Enter pre-operational state to map TPDO
node.nmt.state = 'PRE-OPERATIONAL'
# Map TPDO 1 to transmit the button press counter on changes
node.tpdo[1].clear()
node.tpdo[1].add_variable('Button press counter')
node.tpdo[1].trans_type = 254
node.tpdo[1].enabled = True
# Save TPDO mapping
node.tpdo.save()
node.nmt.state = 'OPERATIONAL'
# Reset button press counter
button.raw = 0
print("Press the button 10 times")
while True:
node.tpdo[1].wait_for_reception()
print("Button press counter: {}".format(node.tpdo['Button press counter'].phys))
if node.tpdo['Button press counter'].phys >= 10:
break
network.disconnect()
Running the above Python code should produce the following output:
.. code-block:: console
Press the button 10 times
Button press counter: 0
Button press counter: 1
Button press counter: 2
Button press counter: 3
Button press counter: 4
Button press counter: 5
Button press counter: 6
Button press counter: 7
Button press counter: 8
Button press counter: 9
Button press counter: 10
Modifying the Object Dictionary
*******************************
The CANopen object dictionary used in this sample application can be
found under :zephyr_file:`samples/subsys/canbus/canopen/objdict` in
the Zephyr tree. The object dictionary can be modified using any
object dictionary editor supporting CANopenNode object dictionary code
generation.
A popular choice is the EDS editor from the `libedssharp`_
project. With that, the
:zephyr_file:`samples/subsys/canbus/canopen/objdict/objdicts.xml`
project file can be opened and modified, and new implementation files
(:zephyr_file:`samples/subsys/canbus/canopen/objdict/CO_OD.h` and
:zephyr_file:`samples/subsys/canbus/canopen/objdict/CO_OD.c`) can be
generated. The EDS editor can also export an updated Electronic Data
Sheet (EDS) file
(:zephyr_file:`samples/subsys/canbus/canopen/objdict/objdicts.eds`).
.. _CANopenNode:
https://github.com/CANopenNode/CANopenNode
.. _EN 50325-4:
https://can-cia.org/groups/international-standardization/
.. _CiA 301:
https://can-cia.org/groups/specifications/
.. _CANopen for Python:
https://github.com/christiansandberg/canopen
.. _can-utils:
https://github.com/linux-can/can-utils
.. _libedssharp:
https://github.com/robincornelius/libedssharp
2d7cc8f774