canopen-vhdl

A lightweight CANopen controller in VHDL

eds2vhdl.py

Generates a VHDL file from a CANopen Electronic Data Sheet (EDS). eds2vhdl.py -h for usage.

Names and Ports

The entity name is derived from ProductName key of the DeviceInfo section Signal and constant names are derived from the ParameterName key All names are scrubbed to be VHDL compatible and follow the NASA style guide

The index number and AccessType key of each object determine how the object is parsed:

• Below 0x2000: (communication objects)
  • const: Declared as constant, unless the mux is specified as a --port argument, then it is an in port signal
  • others: Declared as internal "signal"
• 0x2000 and above: (application objects)
  • const: Declared as "constant"
  • ro: Declared as in port signal
  • rw: Declared as out port signal with output buffer for reading internally
  • wo: Declared as out port signal with additional out port signal suffixed with _strb (strobe) of type std_logic that is pulsed high during SDO download

Data Types

All data types must be explicitly defined in the EDS. No data type validation to CiA301 is performed. Data type lengths of 1-32 support "const", "ro", and "rw" access Data type lengths of 0 (undefined) and greater than 32 support "ro" upload via Segmented SDO interface (see below)

Supported communication objects

Index	Object name	Limitations
0x1000	Device type
0x1001	Error register	or'd with ErrorRegister in port
0x1002	Manufacturer status register	always in port
0x1005	COB-ID SYNC
0x1006	Communication cycle period
0x1007	Synchronous window length	Ineffective, no EMCY
0x1012	COB-ID TIME	consumer only
0x1014	COB-ID EMCY	producer only, mostly generic EECs only, no MSEFs, reset error EMCY write only when no errors
0x1016	Consumer heartbeat time	No SDO abort on duplicate Node-IDs
0x1017	Producer heartbeat time
0x1018	Identity object
0x1019	Synchronous counter overflow value	No EMCY on data length mismatch, no SDO abort if 0x1006 is not zero
0x1021	Store EDS	Uses Segmented SDO interface
0x1022	Store format
0x1029	Error behavior	sub-indices 0x00-0x02 only, error class values 0x00-0x02 only
0x1200	Server SDO paramter	mandatory entries only, expedited download only, supports block upload PSTs <= 4
0x1800	TPDO1 comm. parameter
0x1801	TPDO2 comm. parameter
0x1802	TPDO3 comm. parameter
0x1803	TPDO4 comm. parameter
0x1A00	TPDO1 mapping parameter	const or read-only
0x1A01	TPDO2 mapping parameter	const or read-only
0x1A02	TPDO3 mapping parameter	const or read-only
0x1A03	TPDO4 mapping parameter	const or read-only
0x1F80	NMT Startup	bit 3 (self-starting) only

ErrorRegister

Low-to-high bit transitions perform EMCY write with CanOpen.EMCY_EEC_GENERIC; to-all-zeroes transition performs EMCY write with CanOpen.EMCY_EEC_NO_ERROR

Segmented SDO interface

For transferring DOMAIN data via segmented (normal or block). All signals are synchronous to Clock.

Port	Direction	Data type	FIFO Equivalent	Description
SegmentedSdoMux	out	std_logic_vector(23 downto 0)	Address	Concatenation of object dictionary index and subindex. Ex: 0x101801 for Identity object, Vendor-ID
SegmentedSdoReadEnable	out	std_logic	Enable	Start/!stop: Asserted high during entire data transfer, deasserted when finished or aborted
SegmentedSdoDataReadEnable	out	std_logic	Full	Ready/!Ack: Asserted high until one clock cycle after SegmentedSdoDataValid = '1'
SegmentedSdoData	in	std_logic_vector(55 downto 0)	Data	Initially data size (32-bit max), in bytes, from when SegmentedSdoReadEnable = '1' to first SegmentedSdoDataReadEnable = '1', then segment data with LSB first
SegmentedSdoDataValid	in	std_logic	WriteEnable	Asserted when SegmentedSdoData is valid, deasserted when SegmentedSdoReadValid = '0' or SegmentedSdoReadEnable = '0'

Timing diagram:

Clock                      _|¯|_|¯|_|¯|_|¯|_|¯|_|¯|_|¯|_|¯|_|¯|_|¯···_|¯|_|¯|_

                                __________________________________   ______
SegmentedSdoMux            XXXXX                                  ···      XXX
                                ¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯   ¯¯¯¯¯¯

SegmentedSdoReadEnable     _____|¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯···¯¯¯¯¯|___


SegmentedSdoReadDataEnable _____________|¯¯¯¯¯¯¯|___|¯¯¯¯¯¯¯|___|¯···¯¯¯¯¯|___

                                 _______ ________    ________    _   ______
SegmentedSdoData           XXXXXX size  X   D0   XXXX   D1   XXXX ··· DN   XXX
                                 ¯¯¯¯¯¯¯ ¯¯¯¯¯¯¯¯    ¯¯¯¯¯¯¯¯    ¯   ¯¯¯¯¯¯

SegmentedSdoDataValid      _________________|¯¯¯¯¯¯¯|___|¯¯¯¯¯¯¯|_···¯¯¯¯¯|___

Other Files

eds2mem.py generates a memory file (MEM) from an EDS (or any other) file to be loaded into RAM/ROM, specifically for use with CANopen DOMAIN objects (such as 0x1021: Store EDS) accessed via segmented SDO. eds2mem.py -h for usage.

src/CanOpen_pkg.vhd defines standard CANopen constants and record types, as well as helper functions. Required.

src/CanOpenIndicators.vhd contains a module that can convert the CANopen NMT State and CAN status signals into the appropriate CiA 303-3 indicator signals.

src/SegmentedSdo*.vhd interface adapters between the Segmented SDO interface (above) and various memory configurations (RAM, ROM, etc.).