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VSCP Level II Firmware

Copyright © 2000-2018 Åke Hedman, Grodans Paradis AB,


The VSCP firmware is code that you find in nodes. It is built to be able to fit in the smallest possible device and it is free of assumptions on which transport mechanism that is used.

Anyway it is not a big deal to make a node that follow the the VSCP standard. You should however be aware of what registers are, what events are, what a MDF is, what a decision matrix (DM) is and what a GUID is before you start. You find all that information in the VSCP Specification.

If you are making modules for sale or delivery outside your own lab bench you should probably ask for a GUID series for your device. Send a mail to providing your contact information and ask for a series. You get a series free of charge.

Before you go

You have to chose what type of interface you want to implement in your node. Basically there is two types. Packet based or command based. But you can also skip implemention of a client interface all together and instead actively connect to a VSCP daemon/server instead of waiting for connection.

Normally you should implement all the required parts of VSCP but if you are on very constraint hardware you also have the option to implement a dumb node. A dumb node just has to implement an event sender and send a node heartbeat.

Packet based nodes (Ethernet/UDP/Multicast)

This is a model that works much the same as for Level I firmware. The firmware received VSCP events and send VSCP events. All nodes should implement the heartbeat and capabilities event.

The VSCP Link interface is a telnet interface which is a subset of the VSCP daemon tcp/ip interface. It always handles the following commands

Command Description
NOOP No operation. The response is always “+OK”
QUIT Close the connection
USER Username credentials used to login to the interface.
PASS Password credentials used to login to the interface.
CHALLENGE Used to get a session unique id. Part of log in process.
SEND Send event to node.
RETR Get event from node.
RCVLOOP Enter receive loop.
QUITLOOP Terminates/end receive loop.
CDTA/CHKDATA Check if there is events waiting to be received.
CLRA/CLRALL Clear event input queue.
STAT Get statistical information from node.
INFO Get status information from node.
CHID/GETCHID Get channel id from node.
GGID/GETGID Get GUID for node.
VERS/VERSION Get version for node firmware.
SFLT/SETFILTER Set event filter on interface.
SMSK/SETMASK Set event mask on interface.
DM Decision matrix handling functionality. (optional)
VAR Variable handling functionality. (optional)


The variable handling functionality makes it possible to read registers on a device.


Subcommand Description
READ Read a variable.
WRITE Write a variable.
READVALUE Read a variable value.
WRITEVALUE Write a variable value.

Registers are defined by page,register. So


will return content of register 11 on page 0 as

register - value

In the same manner you write a register with


where value is the new content that should be written to the register.

Abstractions defined in the MDF can be written and read using there name


will return



VAR WRITEVALUE version value

will set the version abstraction to value.


Can be used to read and write decision matrix rows.


start_l2.txt · Last modified: 2018/02/16 18:08 by admin