CAN

The i.MX RT1170 processor includes three FlexCAN FD controllers (flexcan1, flexcan2, and flexcan3). In the current BSP-Zephyr-RT1170-PD26.1.0 release, only flexcan3 (can@40c3c000) is enabled and exposed on the phyCORE-RT1170 module, routed to connector X20 on the phyBOARD-Atlas RT1170 carrier board. You can inspect and exercise this device directly from the Zephyr shell using the built-in can commands, without writing any application code.

Note

The maximum supported CAN data rate is currently 500 kbit/s.

For detailed hardware-level information, refer to the 7.1 FlexCAN chapter in the Hardware Manual.

Requirements

• Two sets of phyBOARD-Atlas RT1170 carrier board

or (to test CAN from a host PC)

• DB9 Male to RS232 Female Cable (Included in development kit)

• CAN Cable

  • PCAN Cable 2

• CAN to USB Adapter

  • PCAN-USB Adapter

  • candleLight FD

Shell Usage

The examples below use two phyBOARD-Atlas RT1170 carrier boards with their CAN transceivers connected together via connector X20, referred to as Device A (sender) and Device B (receiver).

Run can without arguments to list the available subcommands:

uart:~$ can

Expected Output

can - CAN controller commands
Subcommands:
  start     : Start CAN controller
              Usage: start <device>
  stop      : Stop CAN controller
              Usage: stop <device>
  show      : Show CAN controller information
              Usage: show <device>
  bitrate   : Set CAN controller bitrate (sample point and SJW optional)
              Usage: bitrate <device> <bitrate> [sample point] [sjw]
  dbitrate  : Set CAN controller data phase bitrate (sample point and SJW
              optional)
              Usage: dbitrate <device> <data phase bitrate> [sample point] [sjw]
  timing    : Set CAN controller timing
              Usage: timing <device> <sjw> <prop_seg> <phase_seg1> <phase_seg2>
                     <prescaler>
  dtiming   : Set CAN controller data phase timing
              Usage: dtiming <device> <sjw> <prop_seg> <phase_seg1> <phase_seg2>
                     <prescaler>
  mode      : Set CAN controller mode
              Usage: mode <device> <mode> [mode] [mode] [...]
  send      : Enqueue a CAN frame for sending
              Usage: send <device> [-e] [-r] [-f] [-b] <CAN ID> [data] [...]
                     -e  use extended (29-bit) CAN ID
                     -r  send Remote Transmission Request (RTR) frame
                     -f  use CAN FD frame format
                     -b  use CAN FD Bit Rate Switching (BRS)
  filter    : CAN rx filter commands
              Usage: filter <add|remove> <device> ...
  dump      : Dump all CAN controller RX frames
              Usage: dump <device>

Starting the CAN Controller

Before using a CAN controller, start it on both boards:

uart:~$ can start can@40c3c000

Expected Output

uart:~$ can start can@40c3c000
starting can@40c3c000

Checking Controller Status

To inspect a controller’s current configuration and state:

uart:~$ can show can@40c3c000

Expected Output

core clock:      24000000 Hz
max bitrate:     5000000 bps
max std filters: 5
max ext filters: 5
capabilities:    normal loopback listen-only fd triple-sampling
mode:            normal
state:           error-active
rx errors:       0
tx errors:       0
timing:          sjw 1..32, prop_seg 1..64, phase_seg1 1..32, phase_seg2 2..32, prescaler 1..1024
timing data:     sjw 1..8, prop_seg 1..31, phase_seg1 1..8, phase_seg2 2..8, prescaler 1..1024
transceiver:     can-phy0

Sending and Receiving Frames

On Device A, send a CAN frame with standard ID 0x000 and data bytes 12 34 56 78:

uart:~$ can send can@40c3c000 0 12 34 56 78

Expected Output (Device A)

uart:~$ can send can@40c3c000 0 12 34 56 78
enqueuing CAN frame #1 with standard (11-bit) CAN ID 0x000, RTR 0, CAN FD 0, BRS 0, DLC 4
CAN frame #1 successfully sent

On Device B, dump incoming frames to see it arrive:

uart:~$ can dump can@40c3c000

Expected Output (Device B)

uart:~$ can dump can@40c3c000
dumping CAN RX frames on device can@40c3c000, press Ctrl+C to exit
can@40c3c000  --       000   [4]  12 34 56 78

Note

Please refer to the CAN reference documents for other products to learn how to test using a host PC.

Note

For any technical questions, feel free to reach out to PHYTEC’s Support Portal!