RE: [Embedlets-dev] Light Blinker update and uVM serial multidrop network

[James C. <ca...@vi...>]

Hi Ted, All

The RS232-MultiDrop design is very straight forward. All you need is a
single Maxim device to handle the communications between the PC and the
first element of the chain for the voltage conversion and from there on
it looks quite similar to an I2C or 1-wire pullup configuration.

I have created a partial diagram from virtual breadboard in the Scalar
Vector Graphics output (SVG)

If you haven't already got a viewer for SVG you need to install one

http://www.adobe.com/svg/viewer/install/main.html


To note: 
1) The PIC is just a placeholder to show the connection to TX/RX you
have to change the actual pins according to the actual PIC used
obviously
2) The RX/TX top right connect to the MAXIM device or other RS232 level
shifting device.

The idea is very simple,
We are using a pulldown diode to prevent the discrete PIC's from driving
each others outputs to the wrong levels. This works because the master
will transmit and all will listen but only one device will respond to
any one request (it has a matching IP address) so there is no collision
in the return TX all we need to do is to prevent each device from
effecting the output driver of the other devices which we do with the
diode.

I haven't build one yet.. But when I do I will publish more complete
schematics but if you want to get started early this is what I am
thinking.

James Caska
www.muvium.com
uVM - 'Java Bred for Embedded'




-----Original Message-----
From: emb...@li...
[mailto:emb...@li...] On Behalf Of
Ted Kosan
Sent: Thursday, 17 July 2003 7:27 AM
To: emb...@li...
Subject: [Embedlets-dev] Light Blinker update and uVM serial multidrop
network


Topic tags:[ARCH][JAPL][WIRING][DOCS][MGMT][STRATEGY][NEWBIE]
_______________________________________________

I submitted the Global Light Blinker proposal to the JXTA community and
the feedback that I received on the idea was all +1s so I have been
moving ahead with developing the software.

The next step in the process is to submit the project idea for formal
approval and I will do this as soon as I have a working demonstration.

The demonstration application is currently 90% functional and the main
thing that is preventing 100% functionality is a method in the JXTA core
libraries that has not been implemented yet.  I have been using the JXTA
lists in order to resolve this issue as soon as possible.

In the meantime, I am now ready to start working on the reference
implementation hardware design.



James,

Do you happen to have a diagram of your RS232 serial line multidrop
design?  My initial plan was to go with 1-Wire for the reference
hardware but I am very reluctant to deal with Dallas Semiconductor
directly to obtain serial-to-1Wire converters (DS9097Us) and it looks
like we are about 3 months away from having a second source for an
equivalent serial-to-1Wire board.

uVMs using your RS232 multidrop idea seem to be an excellent non-1Wire
based solution to the problem and so I would like to proceed with this
strategy


Ted

__________________________________
Do you Yahoo!?
SBC Yahoo! DSL - Now only $29.95 per month! http://sbc.yahoo.com


-------------------------------------------------------
This SF.net email is sponsored by: VM Ware
With VMware you can run multiple operating systems on a single machine.
WITHOUT REBOOTING! Mix Linux / Windows / Novell virtual machines at the
same time. Free trial click here: http://www.vmware.com/wl/offer/345/0
_______________________________________________
Embedlets-developer mailing list
Emb...@li...
https://lists.sourceforge.net/lists/listinfo/embedlets-developer