Configure the AGL system

Virtual CAN device

Connected to the target, here is how to load the virtual CAN device driver and set up a new vcan device :

modprobe vcan
ip link add vcan0 type vcan
ip link set vcan0 up

You also can named your linux CAN device like you want and if you need name it can0 :

modprobe vcan
ip link add can0 type vcan
ip link set can0 up

CAN device using the USB CAN adapter

Using real connection to CAN bus of your car using the USB CAN adapter connected to the OBD2 connector.

Once connected, launch dmesg command and search which device to use:

dmesg
[...]
[  131.871441] usb 1-3: new full-speed USB device number 4 using ohci-pci
[  161.860504] can: controller area network core (rev 20120528 abi 9)
[  161.860522] NET: Registered protocol family 29
[  177.561620] usb 1-3: USB disconnect, device number 4
[  191.061423] usb 1-2: USB disconnect, device number 3
[  196.095325] usb 1-2: new full-speed USB device number 5 using ohci-pci
[  327.568882] usb 1-2: USB disconnect, device number 5
[  428.594177] CAN device driver interface
[ 1872.551543] usb 1-2: new full-speed USB device number 6 using ohci-pci
[ 1872.809302] usb_8dev 1-2:1.0 can0: firmware: 1.7, hardware: 1.0
[ 1872.809356] usbcore: registered new interface driver usb_8dev

Here device is named can0.

This instruction assuming a speed of 500000kbps for your CAN bus, you can try others supported bitrate like 125000, 250000 if 500000 doesn’t work:

ip link set can0 type can bitrate 500000
ip link set can0 up
ip link show can0
  can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN qlen 10
    link/can
    can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
    bitrate 500000 sample-point 0.875
    tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
    sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1
    clock 16000000

On a Rcar Gen3 board, you’ll have your CAN device as can1 because can0 already exists as an embedded device.

The instructions will be the same:

ip link set can1 type can bitrate 500000
ip link set can1 up
ip link show can1
  can0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UNKNOWN qlen 10
    link/can
    can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
    bitrate 500000 sample-point 0.875
    tq 125 prop-seg 6 phase-seg1 7 phase-seg2 2 sjw 1
    sja1000: tseg1 1..16 tseg2 1..8 sjw 1..4 brp 1..64 brp-inc 1
    clock 16000000

Rename an existing CAN device

You can rename an existing CAN device using following command and doing so move an existing can0 device to anything else and then use another device as can0 . For a Rcar Gen3 board do the following by example:

sudo ip link set can0 down
sudo ip link set can0 name bsp-can0
sudo ip link set bsp-can0 up

Then connect your USB CAN device that will be named can0 by default.

Configure the binding

The binding reads system configuration file /etc/dev-mapping.conf at start to map logical name from signals described in JSON file to linux devices name initialized by the system.

Edit file /etc/dev-mapping.conf and add mapping in section CANbus-mapping.

Default binding configuration use a CAN bus named hs so you need to map it to the real one, here are some examples:

  • Using virtual CAN device as described in the previous chapter:
[CANbus-mapping]
hs="vcan0"
ls="vcan1"
  • Using real CAN device, this example assume CAN bus traffic will be on can0.
[CANbus-mapping]
hs="can0"
ls="can1"
  • On a Rcar Gen3 board there is an embedded CAN device so can0 already exists. So you might want to use your USB CAN adapter plugged to the OBD2 connector, in this case use can1:
[CANbus-mapping]
hs="can1"

CAUTION VERY IMPORTANT: Make sure the CAN bus(es) you specify in your configuration file match those specified in your generated source file with the CAN-config-generator.

Run it, test it, use it.

You can run the binding using afm-util tool, here is the classic way to go :

afm-util run low-can-service@4.0
1

You can find instructions to use afm-util tool here, as well as documentation about Application Framework.

But you can’t control nor interact with it because you don’t know security token that Application Framework gaves it at launch.

So, to test it, it is better to launch the binding manually. In the following example, it will use port 1234 and left empty security token for testing purpose:

afb-daemon --binding=/var/lib/afm/applications/low-can-service/4.0/lib/afb-low-can.so --rootdir=/var/lib/afm/applications/low-can-service/4.0/ --port=1234 --token=1
NOTICE: binding [/usr/lib/afb/afb-dbus-binding.so] calling registering function afbBindingV1Register
NOTICE: binding /usr/lib/afb/afb-dbus-binding.so loaded with API prefix dbus
NOTICE: binding [/usr/lib/afb/authLogin.so] calling registering function afbBindingV1Register
NOTICE: binding /usr/lib/afb/authLogin.so loaded with API prefix auth
NOTICE: binding [/var/lib/afm/applications/low-can-service/4.0/libs//low-can-binding.so] calling registering function afbBindingV1Register
NOTICE: binding /var/lib/afm/applications/low-can-service/4.0/libs//low-can-binding.so loaded with API prefix low-can
NOTICE: Waiting port=1234 rootdir=/var/lib/afm/applications/low-can-service/4.0/
NOTICE: Browser URL= http:/*localhost:1234

On another terminal, connect to the binding using previously installed AFB Websocket CLI tool:

afb-client-demo ws://localhost:1234/api?token=1

You will be on an interactive session where you can communicate directly with the binding API.

The binding provides at this moment 2 verbs, subscribe and unsubscribe, which can take argument by a JSON event object.

The argument value is the CAN message generic_name as described in the JSON file used to generate cpp file for the binding.

To use the AFB Websocket CLI tool, a command line will be like the following:

<api> <verb> <arguments>

Where:

  • API : low-can.
  • Verb : subscribe or unsubscribe
  • Arguments : { “event”: “driver.doors.open” }

Subscription and unsubscription

You can ask to subscribe to chosen CAN event with a call to subscribe API verb with the CAN messages name as JSON argument.

NOTE: If no argument is provided, then you’ll subscribe to all signals at once.

For example from a websocket session:

low-can subscribe { "event": "doors.driver.open" }
ON-REPLY 1:low-can/subscribe: {"jtype":"afb-reply","request":{"status":"success","uuid":"a18fd375-b6fa-4c0e-a1d4-9d3955975ae8"}}

Subscription and unsubscription can take wildcard in their event value.

To receive all doors events :

low-can subscribe { "event" : "doors*" }
ON-REPLY 1:low-can/subscribe: {"jtype":"afb-reply","request":{"status":"success","uuid":"511c872e-d7f3-4f3b-89c2-aa9a3e9fbbdb"}}

Then you will receive an event each time a CAN message is decoded for the event named doors.driver.open with its received timestamp if available:

ON-EVENT low-can/messages.doors.driver.open({"event":"low-can\/messages.doors.driver.open","data":{"name":"messages.doors.driver.open","value":true, "timestamp": 1505812906020023},"jtype":"afb-event"})

Notice that event shows you that the CAN event is named messages.doors.driver.open but you ask for event about doors.driver.open.

This is because all CAN messages or diagnostic messages are prefixed by the JSON parent node name, messages for CAN messages and diagnostic_messages for diagnostic messages like OBD2.

This will let you subscribe or unsubcribe to all signals at once, not recommended, and better make filter on subscribe operation based upon their type. Examples:

low-can subscribe { "event" : "*speed*" } --> will subscribe to all messages with speed in their name. Search will be make without prefix for it.
low-can subscribe { "event" : "speed*" } --> will subscribe to all messages begin by speed in their name. Search will be make without prefix for it.
low-can subscribe { "event" : "messages*speed*" } --> will subscribe to all CAN messages with speed in their name. Search will be on prefixed messages here.
low-can subscribe { "event" : "messages*speed" } --> will subscribe to all CAN messages ending with speed in their name. Search will be on prefixed messages here.
low-can subscribe { "event" : "diagnostic*speed*" } --> will subscribe to all diagnostic messages with speed in their name. Search will be on prefixed messages here.
low-can subscribe { "event" : "diagnostic*speed" } --> will subscribe to all diagnostic messages ending with speed in their name. Search will be on prefixed messages here.

You can stop receiving event from it by unsubscribe the signal the same way you did for subscribe

low-can unsubscribe { "event": "doors.driver.open" }
ON-REPLY 2:low-can/unsubscribe: {"jtype":"afb-reply","request":{"status":"success"}}
low-can unsubscribe { "event" : "doors*" }
ON-REPLY 3:low-can/unsubscribe: {"jtype":"afb-reply","request":{"status":"success"}}

Filtering capabilities

It is possible to limits received event notifications into minimum and maximum boundaries as well as doing frequency thinning. This is possible using the argument filter with one or more of the filters available :

  • frequency: specify in Hertz the frequency which will be used to getting notified of new CAN events for the designated signal. If, during the blocked time, further changed CAN messages are received, the last valid one will be transferred after the lockout with a RX_CHANGED.
  • min: Minimum value that the decoded value needs to be above to get pushed to the subscribed client(s).
  • max: Maximum value that the decoded value needs to be below to get pushed to the subscribed client(s)

Order doesn’t matter neither the number of filters chosen, you can use one, two or all of them at once.

Usage examples :

low-can subscribe {"event": "messages.engine.speed", "filter": { "frequency": 3, "min": 1250, "max": 3500}}
low-can subscribe {"event": "messages.engine.load", "filter": { "min": 30, "max": 100}}
low-can subscribe {"event": "messages.vehicle.speed", "filter": { "frequency": 2}}

Get last signal value and list of configured signals

You can also ask for a particular signal value on one shot using get verb, like this:

low-can get {"event": "messages.engine.speed"}
ON-REPLY 1:low-can/get: {"response":[{"event":"messages.engine.speed","value":0}],"jtype":"afb-reply","request":{"status":"success"}}

CAUTION Only one event could be requested.

Also, if you want to know the supported CAN signals loaded by low-can, use verb list

low-can list
ON-REPLY 2:low-can/list: {"response":["messages.hvac.fan.speed","messages.hvac.temperature.left","messages.hvac.temperature.right","messages.hvac.temperature.average","messages.engine.speed","messages.fuel.level.low","messages.fuel.level","messages.vehicle.average.speed","messages.engine.oil.temp","messages.engine.oil.temp.high","messages.doors.boot.open","messages.doors.front_left.open","messages.doors.front_right.open","messages.doors.rear_left.open","messages.doors.rear_right.open","messages.windows.front_left.open","messages.windows.front_right.open","messages.windows.rear_left.open","messages.windows.rear_right.open","diagnostic_messages.engine.load","diagnostic_messages.engine.coolant.temperature","diagnostic_messages.fuel.pressure","diagnostic_messages.intake.manifold.pressure","diagnostic_messages.engine.speed","diagnostic_messages.vehicle.speed","diagnostic_messages.intake.air.temperature","diagnostic_messages.mass.airflow","diagnostic_messages.throttle.position","diagnostic_messages.running.time","diagnostic_messages.EGR.error","diagnostic_messages.fuel.level","diagnostic_messages.barometric.pressure","diagnostic_messages.ambient.air.temperature","diagnostic_messages.commanded.throttle.position","diagnostic_messages.ethanol.fuel.percentage","diagnostic_messages.accelerator.pedal.position","diagnostic_messages.hybrid.battery-pack.remaining.life","diagnostic_messages.engine.oil.temperature","diagnostic_messages.engine.fuel.rate","diagnostic_messages.engine.torque"],"jtype":"afb-reply","request":{"status":"success","uuid":"32df712a-c7fa-4d58-b70b-06a87f03566b"}}

Write on CAN buses

A new capability as been introcuded to be able to write on handled CAN buses. Two modes could be used for that which is either specifying the CAN bus and a RAW CAN message either by specifying a defined signal and its value.

Examples:

# Write a raw can frame to the CAN id 0x620
low-can write { "bus_name": "hs", "frame": { "can_id": 1568, "can_dlc":
8, "can_data": [ 255,255,255,255,255,255,255,255]} }
# Write a signal's value.
low-can write { "signal_name": "engine.speed", "signal_value": 1256}

To be able to use write capability, you need to add the permission urn:AGL:permission::platform:can:write to your package configuration file that need to write on CAN bus through low-can api.

Then in order to write on bus, your app needs to call verb auth before calling write, to raise its LOA, Level Of Assurance, which controls usage of verb write.

Using CAN utils to monitor CAN activity

You can watch CAN traffic and send custom CAN messages using can-utils preinstalled on AGL target.

To watch watch going on a CAN bus use:

candump can0

Or for an USB CAN adapter connected to porter board:

candump can1

Send a custom message:

cansend can0 ID#DDDDAAAATTTTAAAA

You can also replay a previously dumped CAN logfiles. These logfiles can be found in can_samples directory under Git repository. Following examples use a real trip from an Auris Toyota car.

Trace has been recorded from a CAN device can0 so you have to map it to the correct one you use for your tests.

Replay on a virtual CAN device vcan0:

canplayer -I trip_test_with_obd2_vehicle_speed_requests vcan0=can0

Replay on a CAN device can0:

canplayer -I trip_test_with_obd2_vehicle_speed_requests can0

Replay on a CAN device can1 (porter by example):

canplayer -I trip_test_with_obd2_vehicle_speed_requests can1=can0