Skip to main content

CAN FD

These commands are available three ways — in the FREE-WILi GUI app, in a serial terminal, and on the device itself. See Connecting it to a computer for how to reach them.

Stream CAN(FD)​

Enables or disables streaming of received CAN/CAN-FD frames and bus errors from the selected channel to the host.

Example​

o 0 1   # enable streaming on channel 0
o 1 0   # disable streaming on channel 1

Notes​

  • Each channel streams independently; toggling one channel does not affect the other.
  • If only channel parses successfully but enabled does not, streaming on that channel is forced off as a safety fallback.
  • All frames will be received unless a receive filter is configured (see Setup Filter) so the controller actually accepts the frames you want to observe.
  • FreeWili2 only has one CAN channel (channel 2 is reserved for future orcas)

How to use it — press o. At the prompt, enter: Channel and enable state.

What you enter — channel, enabled.

Transmit CAN(FD)​

Transmits a single CAN 2.0 or CAN-FD frame on the selected channel. The frame is queued to the controller's transmit FIFO and sent as soon as the bus permits.

Valid payload lengths (DLC)​

  • Classic CAN (canFd = 0): 0–8 bytes.
  • CAN-FD (canFd = 1): 0–8, 12, 16, 20, 24, 32, 48, or 64 bytes.

Any other byte count is rejected and the command reports Invalid.

Examples​

# Classic CAN, standard ID 0x123, 4 data bytes
w 0 0x123 0 0 DE AD BE EF

# Classic CAN, extended ID 0x1ABCDEF, no data (remote/empty frame)
w 0 0x01ABCDEF 0 1

# CAN-FD, standard ID 0x200, 16-byte payload
w 0 0x200 1 0 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF

Notes​

  • The frame is queued to the transmit FIFO; if the FIFO is full or the bus is unavailable the frame may be delayed.
  • Make sure the controller's bit timing (and FD data-phase timing) is configured before transmitting — see the Neptune/Orca setup commands.
  • For periodic / repeated transmission use Transmit CAN(FD) Periodic instead.

How to use it — press w. At the prompt, enter: Channel ArbID (hex) isCANFD isXtd Bytes (hex).

What you enter — channel, arb_id, can_fd, xtd_id, data_in.

Transmit CAN(FD) Periodic​

Configures one of the controller's periodic-transmit slots. Each slot holds a CAN/CAN-FD frame that is re-sent automatically at a fixed interval (or as fast as the bus permits) until it is disabled.

Valid payload lengths (DLC)​

  • Classic CAN (canFd = 0): 0–8 bytes.
  • CAN-FD (canFd = 1): 0–8, 12, 16, 20, 24, 32, 48, or 64 bytes.

Any other byte count is rejected and the command reports Invalid.

Short form (toggle only)​

If only the first arguments parse — index, enable, and channel — the previously configured frame in that slot is simply enabled or disabled without being re-loaded:

p <index> <enable> <period_ignored> <channel>

In practice, to just turn a configured slot off, the simplest form is:

p 0 0 0 0     # disable slot 0 on channel 0

Examples​

# Slot 0 on channel 0: send classic standard-ID 0x123 with 4 data bytes every 10 ms
p 0 1 10000 0 0x123 0 0 DE AD BE EF

# Slot 1 on channel 0: send CAN-FD standard-ID 0x200, 16-byte payload, as fast as possible
p 1 1 0 0 0x200 1 0 00 11 22 33 44 55 66 77 88 99 AA BB CC DD EE FF

# Slot 2 on channel 0: extended-ID 0x1ABCDEF, no data, every 1 s
p 2 1 1000000 0 0x01ABCDEF 0 1

# Disable slot 0 on channel 0
p 0 0 0 0

Notes​

  • Frames are queued to the transmit FIFO; if the FIFO is full or the bus is unavailable the frame is delayed until room becomes available.
  • period = 0 ("as fast as possible") fills any free TX FIFO slots every service tick and can saturate the bus — use with care.
  • Make sure the controller's bit timing (and FD data-phase timing) is configured before transmitting — see the Neptune/Orca setup commands.
  • Periodic slots are independent per channel; slot 0 on channel 0 is unrelated to slot 0 on channel 1.
  • To send a single, one-shot frame instead of a periodic stream, use Transmit CAN(FD).

How to use it — press p. At the prompt, enter: index enable period (us) Channel (0-1) ArbID (hex) isCANFD isXtd Bytes (hex).

What you enter — index, enable, period, channel, arb_id, can_fd, xtd_id, data_in.

Setup Filter​

Configures one of the CAN controller's hardware receive filters. Frames that do not match an enabled filter are dropped before reaching the stream / FIFO. If there are no filters configure Stream CAN(FD) shows all messages.

Examples​

# Enable filter 0 on channel 0, standard ID, accept only ID 0x123
f 0 0 1 0 0x7FF 0x123

# Accept any standard ID 0x100–0x10F (mask off low 4 bits)
f 0 1 1 0 0x7F0 0x100

# Same as above, but only frames whose first data byte is 0xA5
f 0 1 1 0 0x7F0 0x100 0xFF 0xA5 0x00 0x00

# Disable filter 2 on channel 0 (only the first three args are needed)
f 0 2 0

Notes​

  • Omitting mask/accept is only valid when enable is 0; otherwise parsing fails and the command reports Invalid.
  • If the byte-filter arguments are omitted, all four byte mask/accept values are cleared to 0 (i.e., no byte filtering).
  • Byte filtering applies to standard IDs only; do not rely on maskb0/maskb1 when xtdId = 1.
  • Filters are re-applied to the controller immediately (setupFilters(false)) after a successful update.
  • if no filters are configured all frames will be received.

How to use it — press f. At the prompt, enter: channel (0-1), index (0-32), enable, isXTD, mskID, ID, [(optional) mskb0, b0, mskb1, b1].

What you enter — channel, index, enable, xtd_id, mask, accept, maskb0, accept_b0, maskb1, accept_b1.

Read CAN Register(s)​

Reads one or more consecutive 32-bit Special Function Registers (SFRs) from the selected CAN controller and returns them to the host as name/value pairs.

Example​

# Read 4 words starting at SFR address 0x000 on channel 0
r 0 0x000 4

Notes​

  • The command operates directly on the CAN controller's SFR space — be careful when reading registers that have read-side-effects (e.g. interrupt/error status clears).
  • Use Set CAN Register (s) to write a register, and the Neptune/Orca setup commands for normal bit-timing and configuration changes.
  • Returns Invalid if channel is out of range or any argument fails to parse.
  • FreeWili GUI decodes these values for helpful debugging

How to use it — press r. At the prompt, enter: channel (0-1) address (hex) wordcount.

What you enter — channel, start_address, word_count.

Set CAN Register​

Writes a single 32-bit (or 8-bit) Special Function Register (SFR) on the selected CAN controller. This is a direct register write — bypassing the normal setup commands — and should be used only when you know exactly what the controller expects.

Examples​

# Write the 32-bit value 0x00000004 to SFR 0x000 on channel 0
s 0 0x000 4 0x00000004

# Write the single byte 0xA5 to SFR 0x010 on channel 0
s 0 0x010 1 0xA5

Notes​

  • This is a raw register write — be careful with registers that have write-side-effects (mode changes, FIFO control, interrupt clears, etc.).
  • For normal bit-timing and configuration changes, prefer the Neptune/Orca setup commands instead of writing SFRs directly.
  • Use Read CAN Register(s) (r) to verify the value after writing.
  • Returns Invalid if channel is out of range or any argument fails to parse.

How to use it — press s. At the prompt, enter: channel (0-1) address (hex) bytesize (1,4) word (hex).

What you enter — channel, start_address, byte_count, word_to_write.

See also: CAN (FD) panel — the on-screen panel for this.