Hardware¶

The bus the driver talks on: settings, identifiers, the exact bytes of each frame and the objects it names.

Bus settings¶

Setting	Value
Frame format	Classic CAN 2.0A: 11-bit identifier, no RTR, 0 to 8 data bytes (`VortexCanFrame`)
Bit rate	Set by your CAN controller, the same on every node; the Vortex V1 HAL uses 500 kbit/s
Node IDs	1 to 127; NMT target 0 addresses every node
Termination	120 Ω at each end of the bus
Vortex V1 controller	ESP32-C6 TWAI, TX on GPIO14, RX on GPIO15, transceiver standby on the PCAL95555 expander

VortexCanFrame also carries extended and rtr flags; the session always sends them false.

Identifiers¶

Frame	COB-ID	Sent by this driver
NMT command	`0x000`	Yes, `sendNmt()`
SDO request (client to server)	`0x600 + node`	Yes, `sdoDownloadExpedited()`
SDO response (server to client)	`0x580 + node`	No: read it yourself
Boot-up and heartbeat	`0x700 + node`	No
EMCY	`0x080 + node`	No
PDOs (default set)	`0x180 + node` to `0x500 + node`	No

NMT frame¶

ID 0x000, DLC 2.

Byte	Content
0	Command, from `NmtCommand`
1	Target node ID; 0 for all nodes

Command	Byte 0
`NmtCommand::Start`	`0x01`
`NmtCommand::Stop`	`0x02`
`NmtCommand::PreOperational`	`0x80`
`NmtCommand::ResetNode`	`0x81`
`NmtCommand::ResetCommunication`	`0x82`

SDO expedited download frame¶

ID 0x600 + node, DLC 8, little-endian.

Byte	Content
0	Command specifier: `0x2F` for 1 byte, `0x2B` for 2 bytes, `0x23` for 4 bytes
1, 2	Index, low byte first
3	Sub-index
4 to 7	Value, low byte first; bytes past the size are 0

A size other than 1, 2 or 4 is refused before anything is sent.

sequenceDiagram
    participant H as Host (VortexHostSession)
    participant N as Vortex node 5
    H->>N: 0x000  01 05  (NMT start)
    Note over N: Operational
    H->>N: 0x605  2F 60 60 00 03 00 00 00  (0x6060:00 = 3)
    N-->>H: 0x585  60 60 60 00 00 00 00 00  (download confirmed)
    Note over H: the response is read by your code, not the session

Object dictionary constants¶

The named objects in VortexProtocol.hpp. The node's object dictionary (its EDS, or the CANopenNode tables in the device firmware) is authoritative.

Constant	Value	Kind	Header comment
`kIdxErrorRegister`	`0x1001`	index	CiA 301 — Error register (0x1001) subindex 0
`kIdxPredefError`	`0x1003`	index	CiA 301 — Pre-defined error field (0x1003) sub 0 = number of errors
`kIdxErrorBehavior`	`0x1029`	index	CiA 301 — Error behavior (0x1029); sub 1 = communication error
`kIdxControlword`	`0x6040`	index	CiA 402 — Controlword (0x6040) — used for drive state machine
`kIdxStatusword`	`0x6041`	index	CiA 402 — Statusword (0x6041)
`kIdxModesOfOperation`	`0x6060`	index	CiA 402 — Modes of operation (0x6060)
`kIdxModesDisplay`	`0x6061`	index	CiA 402 — Modes of operation display (0x6061)
`kIdxPosActual`	`0x6064`	index	CiA 402 — Position actual value (0x6064)
`kIdxVelActual`	`0x606C`	index	CiA 402 — Velocity actual value (0x606C)
`kIdxVendorBase`	`0x2000`	index	Proposed HardFOC vendor range 0x2000–0x2FFF, inside the CiA 301 manufacturer-specific area (0x2000–0x5FFF). Reserve sub-ranges as products solidify.
`kIdxVendorDeviceId`	`0x2000`	index	Example: 0x2000:01 — u32 build id / device magic (placeholder)
`kSubVendorDeviceId`	`0x01`	sub-index

Source: inc/vortex/VortexProtocol.hpp.

tests/protocol checks every index and NMT command byte in this table against CiA 301 and CiA 402 at compile time (Testing).

Reference documents¶

Document	What it defines
CiA 301 (CAN in Automation)	CANopen application layer: NMT, SDO, PDO, object dictionary
CiA 402 (CAN in Automation)	Drive profile: controlword, statusword, modes of operation
Vortex V1 hardware	The board, its CAN pins and transceiver

Next: Architecture.