RE: [CAD_CAM_EDM_DRO] [EE]: USB stepper drive system

List
I have been thinking in this same direction. Currently I have been trying
to get my hands on a NetChip Net2890 Evaluation Board.
http://www.netchip.com/products/2890eb.htm This board contains a USB chip
and a 8051 processor on the board. In addition, the board contains a
parallel port. The kit is suppose to supply all source code for both the
8051 and the PC end.
The theory is to have a distributed processing arrangement where the PC
parses the Gcodes and develops step and direction commands along with some
sort of a timing index. This 'packet' would be sent via USB to the board
which would handle the timing and output through the parallel port to motor
control boards.
At this point, I am still trying to get a $ response from the local
distributer.

Dennis




On Tuesday, December 19, 2000 11:57 PM, Lawrence Glaister
[SMTP:lg@...] wrote:

>
> There has been a lot of talk lately on the list promoting the

development

> of
> some "smart hardware" to supplement the PC's poor performance. The

second

> item that is rearing its ugly head is that pc's are rapidly losing their
> ISA
> slots and their serial/parallel ports. I also subscribe to the usb-devel
> list and am getting a pretty good feel for what usb is capable of. I use
> EMC
> as the PC end smarts. It basically works well as an open source gcode
> interpreter that expects to output a drive signal and receive back an
> encoder signal for each axis every 1ms or so (programmable). The usb bus
> can
> be thought of as a fast 12mb/sec serial port (about 1/2 of this is

actually

> usable). I am starting to think along the lines of a usb board that
> contains
> some number of rate generators (like Marriss's DDS system or even pic

based

> software DDS) to generate the stepper drive signals smoothly and the

same

> number of encoder interfaces (either in hardware counters or possibly

pic

> based software interfaces). The interface would use an isosyncronous

read

> port and a write port to read/write the command/status signals every ms.

A

> four channel card would cover most applications although once design is

a

> little further along, it may be possible to put 6 axis on a card and
> produce
> them in various states of population. USB support is getting pretty good
> under linux, with quite a few example drivers. Between the lists, there

is

> a
> lot of talent available... where to we need to be in a year from now?

Would

> USB make sense in a shop environment for getting machine control
> information
> in/out of the computer?
> Would DAC outputs for servos make sense? Would +-50ma outputs make sense
> for
> driving hydraulic servo valves? How much would the board cost to

produce?

> It
> is going to be hard to beat the cost of an add-in parallel port. The

card

> would definitely make laptops or low end Macs like an iMac attractive as

a

> dedicated controller. Just some ideas to think about for the next
> generation
> cnc controllers.
> =======================================================
> Lawrence Glaister VE7IT email: lg@...
> 1462 Madrona Drive http://jfm.bc.ca
> Nanoose Bay BC Canada
> V9P 9C9
> =======================================================
>
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