CAN
The phyCORE-AM62x SOM provides Controller Area Network (M_CAN) ports. These interfaces support CAN and CAN FD (flexible data-rate) specifications, conforming with CAN protocol version 2.0 part A, B and ISO 11898-1:2015. This guide will walk-through the basic usage of this interface by transferring data to and from a host PC. To learn more information about the phyCORE-AM62x CAN serial interface, please see section 7.1 in the Hardware Manual.
Interface Name |
Hardware Reference |
|---|---|
main_mcan0 |
X9 |
mcu_mcan0 |
X17 (Expansion Connector) |
mcu_mcan1 |
X17 (Expansion Connector) |
Requirements
DB9 Male to RS232 Female Cable (Included in development kit)
CAN Cable
CAN to USB Adapter
Setup the CAN Network
Connect a D-sub 9 ribbon cable (included in development kit) to the CAN0 connector X9 (red line indicates Pin 1).
Connect the CAN to USB adapter to your host PC (USB port) and the D-sub 9 ribbon cable that is now attached to the CAN0 connector X9 on the development kit.
Setup CAN Software
Step 1: Install can-utils on the Host System
To use the necessary CAN tools, install the can-utils package on your host system:
sh-host:~$ sudo apt update
sh-host:~$ sudo apt install can-utils
Step 2: Verify Matching CAN Bitrates on Host and Target
Ensure that the CAN bitrates on both the host and target systems are identical. Check the bitrate using the following commands:
On the target (e.g., main_mcan0):
phyboard-lyra-am62xx-3:~# ip -details link show main_mcan0 | grep bitrate
bitrate 500000 sample-point 0.875
On the host (e.g., can0):
sh-host:~$ ip -details link show can0 | grep bitrate
bitrate 500000 sample-point 0.800
dbitrate 8000000 dsample-point 0.800
Step 3: Adjust CAN Bitrate if Needed
If the bitrate or sample point differs between the host and target, temporarily update the configuration using these commands:
phyboard-lyra-am62xx-3:~# ip link set main_mcan0 down
phyboard-lyra-am62xx-3:~# ip link set main_mcan0 up type can bitrate 500000 sample-point 0.800
Changing the CAN interface
There are two ways to modify the CAN interface configuration. This section will explain how to change the CAN bitrate from 500 kbit/s to 1 Mbit/s.
Runtime Configuration
To change the interface on the running system:
Edit the network configuration file:
phyboard-lyra-am62xx-3:~# vi /lib/systemd/network/11-main_mcan.network
Modify the Address line under the [CAN] section:
[CAN] BitRate=1000000
Restart the network service:
phyboard-lyra-am62xx-3:~# systemctl restart systemd-networkd
Build-time Configuration
To permanently change the default static IP:
Edit the network configuration in your BSP layer:
meta-ampliphy/recipes-core/systemd/systemd-conf/|intf-can0-service-name|Update the bitrate line as shown above
Rebuild the BSP image
Send CAN Messages
In this example, you’ll verify data transfer from the phyCORE-AM62x to the host PC via CAN.
In a terminal on the host PC, use candump to capture all error and data frames on the can0 interface:
sh-host:~$ candump can0,0:0,#FFFFFFFF
Note
You can explore more options for using candump by running:
sh-host:~$ man candump
In another terminal, access the Linux console on the phyCORE-AM62x and send an example CAN frame using the following command:
phyboard-lyra-am62xx-3:~# cansend main_mcan0 000#FE.ED.C0.DE.CA.FE.BA.BE
After sending, the candump terminal should display the transmitted CAN message. For example:
sh-host:~$ candump can0,0:0,#FFFFFFFF
can0 000 [8] FE ED C0 DE CA FE BA BE
You can modify the three-character CAN ID (before the # symbol) or the data payload (after the #) to send different messages.
candump runs continuously in a loop. Press Ctrl+C to terminate the tool.
Receive CAN Messages
After verifying data transfer from the phyCORE-AM62x to the host PC, you can test the reverse direction by following these steps.
In the Linux console on the phyCORE-AM62x, use candump to capture all error and data frames on the |intf-can0-dev-name| interface:
phyboard-lyra-am62xx-3:~# candump main_mcan0,0:0,#FFFFFFFF
On the host PC, send an example CAN frame using the following command:
sh-host:~$ cansend can0 005#CA.FE.BA.BE.FE.ED.C0.DE
After sending the frame, the candump terminal on the phyCORE-AM62x should display the transmitted CAN message. For example:
phyboard-lyra-am62xx-3:~# candump main_mcan0,0:0,#FFFFFFFF
main_mcan0 005 [8] CA FE BA BE FE ED C0 DE
As before, feel free to modify the three-character CAN ID (before the # symbol) or the data payload (after the #) to test different messages.
candump runs in a continuous loop. Use Ctrl+C to terminate it when finished.
Generate CAN Messages
Manually sending data frames is useful for testing specific commands and verifying connectivity. However, the can-utils package also includes a tool called cangen that automatically generates CAN frames with varying CAN IDs and data content.
In the Linux console of the phyCORE-AM62x, use candump to monitor incoming CAN messages:
phyboard-lyra-am62xx-3:~# candump main_mcan0,0:0,#FFFFFFFF
In another terminal on the host PC, use cangen to generate random CAN frames:
sh-host:~$ cangen can0
Back on the phyCORE-AM62x, the candump terminal will display multiple incoming CAN messages, similar to the following example:
phyboard-lyra-am62xx-3:~# candump main_mcan0,0:0,#FFFFFFFF
main_mcan0 144 [7] 3C 51 75 7C CA B1 47
main_mcan0 413 [3] 92 B3 8D
main_mcan0 15A [8] D8 B4 00 68 64 FA D2 2E
main_mcan0 0A6 [8] 5E 97 E9 18 40 5A 6E 5E
main_mcan0 44C [8] 6A 30 39 11 F7 1C 60 34
main_mcan0 34F [8] 82 BA E1 7B 1F 3D FD 54
main_mcan0 2A3 [3] 09 04 77
main_mcan0 17E [8] FE 75 54 74 C2 1A 80 79
main_mcan0 7B2 [8] 8C CC C7 55 C6 EB 72 5D
main_mcan0 48E [8] F4 2E 69 63 E8 35 3B 4F
main_mcan0 2EC [8] 4C 30 0E 7E 92 D3 77 45
main_mcan0 56A [8] D2 2D E6 23 B7 B1 04 6F
main_mcan0 253 [8] AE CE 64 23 A3 6D CC 4E
main_mcan0 448 [1] C2
main_mcan0 274 [8] 63 B2 E1 24 F2 BB 28 2A
main_mcan0 146 [1] B4
main_mcan0 79C [1] BF
main_mcan0 35F [3] 12 CA 2D
main_mcan0 77F [8] DE 11 D3 6E EA 04 69 01
Press Ctrl+C to stop cangen on the host PC and exit the listening mode on the phyCORE-AM62x.
CAN FD
To verify if CAN FD is enabled, check the statistics of the CAN interface:
phyboard-lyra-am62xx-3:~# ip -details link show main_mcan0
3: main_mcan0: <NOARP,UP,LOWER_UP,ECHO> mtu 16 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
link/can promiscuity 0 allmulti 0 minmtu 0 maxmtu 0
can state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
bitrate 500000 sample-point 0.800
tq 12 prop-seg 63 phase-seg1 64 phase-seg2 32 sjw 16 brp 1
m_can: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp_inc 1
m_can: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..32 dbrp_inc 1
clock 80000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535 gro_max_size 65536 gso_ipv4_max_size 65536 gro_ipv4_max_size 65536 parentbus platform parentdev 20701000.can
If the interface does not display can <FD> in the output or lacks the dbitrate property, CAN FD needs to be enabled. Use the following commands to enable it. Ensure the dbitrate and dsample-point match the counterpart system or define common values.
phyboard-lyra-am62xx-3:~# ip link set main_mcan0 down
phyboard-lyra-am62xx-3:~# ip link set main_mcan0 up type can bitrate 500000 sample-point 0.800 fd on dbitrate 500000 dsample-point 0.800
Verify the updated configuration.
phyboard-lyra-am62xx-3:~# ip -details link show main_mcan0
3: main_mcan0: <NOARP,UP,LOWER_UP,ECHO> mtu 72 qdisc pfifo_fast state UP mode DEFAULT group default qlen 10
link/can promiscuity 0 allmulti 0 minmtu 0 maxmtu 0
can <FD> state ERROR-ACTIVE (berr-counter tx 0 rx 0) restart-ms 0
bitrate 500000 sample-point 0.800
tq 12 prop-seg 63 phase-seg1 64 phase-seg2 32 sjw 16 brp 1
m_can: tseg1 2..256 tseg2 2..128 sjw 1..128 brp 1..512 brp_inc 1
dbitrate 500000 dsample-point 0.800
dtq 50 dprop-seg 15 dphase-seg1 16 dphase-seg2 8 dsjw 4 dbrp 4
m_can: dtseg1 1..32 dtseg2 1..16 dsjw 1..16 dbrp 1..32 dbrp_inc 1
clock 80000000 numtxqueues 1 numrxqueues 1 gso_max_size 65536 gso_max_segs 65535 tso_max_size 65536 tso_max_segs 65535 gro_max_size 65536 gso_ipv4_max_size 65536 gro_ipv4_max_size 65536 parentbus platform parentdev 20701000.can
As you can see, the interface now has CAN FD enabled and a dbitrate set.
Testing the CAN FD Connection
The can-utils package includes canfdtest, a tool for testing CAN FD communication.
Run the following command to the Host PC:
sh-host:~$ canfdtest -v can0
Open a terminal on the phyCORE-AM62x and run the command with the
-goption to generate messages. Add-l 10000to limit the test to 10,000 messages:
phyboard-lyra-am62xx-3:~# canfdtest -v -g -l 10000 main_mcan0 interface = main_mcan0, family = 29, type = 3, proto = 1 ....................................... Test messages sent and received: 10000 Exiting...
canfdtest instances will run in a loop. Press Ctrl+C on the Host PC to stop the test.