Re: Real Time sharing of data between WinCE systems?
- From: "Paul G. Tobey [eMVP]" <p space tobey no spam AT no instrument no spam DOT com>
- Date: Thu, 17 May 2007 11:39:19 -0700
Maybe you can find CAN controllers that will work from the hardware side,
but you'll have to write CE drivers for them. If it's not a board or a
dongle that plugs into a standard interface on some device's bus, I wouldn't
expect to find a CE driver for it.
Paul T.
"Martin Hughes" <martin@xxxxxxxxxxxxxxx> wrote in message
news:uZAE05KmHHA.4852@xxxxxxxxxxxxxxxxxxxxxxx
Hi Chris,
I think CAN would be ideal for the non-video networking of systems.
Maybe the best thingto do would be to separate the video networking from
the data networking and run them on 2 systems.
I agree that Ethernet is more generally available, but given the explosion
of CAN microcontrollers recently (and relatively cheap RS232/USB to CAN
adapters) CAN is not really that much more complicated.
As you mentioned, CAN is also built for noisy/hostile environments.
When you say "short" bus lengths, could you define that a little more
precisely? The UAV I am building is 3.5m long, so given wiring, the bus is
unlikely to be more than 4m long maximum...
A custom/home grown jobbie would be great, and certainly fun, but it would
also involve quite a bit of additional work, and I would really like to
concentrate on the systems design and programming, and not have to worry
too much about comms interfaces!
Cheers,
Martin
"<ctacke/>" <ctacke[at]opennetcf[dot]com> wrote in message
news:udsYI0JmHHA.4840@xxxxxxxxxxxxxxxxxxxxxxx
CAN and Ethernet sound like a good routes. With CAN all devices can see
data on the bus but you can "direct" messages to a specific target. The
overhead is low, and CAN speed is a least relatively fast (1Mbit/s on
short bus lengths) and works well in a noisy environment.
Ethernet would allow UDP for broadcasts, and while it has higher packet
overhead, that's offset by the fact you can get 100Mbit controllers.
Ethernet is probably more "generally available" on off-the-shelf devices.
Of course SPI could have very low "packet" overhead and the top speed is
generally clock limited, but is really intended for 1:1 comms.
Of source you could just do a home-grown 2-wire synchronous serial
interface that could broadcast. You could bit-bang it on GPIOs from the
processor at probably a really fast rate depending on your processor
speed. Turn off interrupts on the clock line when sending data, on when
you're not. Maybe add a 3rd line for bus control to prevent data
collision. The more I think about it, the more fun this option sounds.
--
Chris Tacke, Embedded MVP
OpenNETCF Consulting
Managed Code in an Embedded World
www.OpenNETCF.com
"Martin Hughes" <martin@xxxxxxxxxxxxxxx> wrote in message
news:ODT3s8ImHHA.4240@xxxxxxxxxxxxxxxxxxxxxxx
Hi bruce,
Thanks for the reply.
The requirements are reasonably straightforward. The quantity of data
will be quite high at maximum load (compressed video will be part of the
data swap) but under low conditions it will simply be ACSII data
streaming backwards and forwards.
The systems will be very close to each other - there are 3 (possibly 4)
systems onboard a UAV, all gathering and processing different data.
- System 1 is the IVSC (Integrated Vehicle Systems Controller) which
incudes the flight control system, autopilot and flight plan management
systems, flight augmentation system, and the subsystem controllers
(fuel, pneumatics, gear & brake management, electrical etc.)
- System 2 is the stores management system which controls and processes
data from onboard cameras and video cameras, and controls the actuators
for the cameras.
- System 3 is the Data Acquisition Concentrator, which takes data from
ALL the sensors (positional, air data, radar altimeter, GPS etc etc) and
also controls the Tx/Rx stream sent and received from the ground.
All these systems need to share data in real time. I looked at RS232,
but ideally it needs to be a star network (all the data from all the
systems needs to be available to all the other systems), which is why I
was looking at ethernet. I don't know if it is robust enough though, and
there is a lot of extraneous data (handshaking etc) which could slow the
network down.
Cheers,
Martin
"Bruce Eitman [eMVP]" <beitman.nospam@xxxxxxxxxxxxxxxxxxxxxx> wrote in
message news:OI6VGUImHHA.4876@xxxxxxxxxxxxxxxxxxxxxxx
Threre a lots of ways to exchange data between Windows CE systems, the
decision of course will have a lot to do with your overal requirements
including quantity of data, proximity of the systems to each other and
of course cost.
I have two systems sharing large quantities of data via SPI BUS, but
the two are touching. I have others using CAN/J1708/RS232 (pick one)
to do smaller data over longer distances. I have many systems using
Ethernet (wired and wireless). USB could be used, but would not be my
first choice. I suspect that others are using shared memory on a
system BUS.
--
Bruce Eitman (eMVP)
Senior Engineer
beitman AT applieddata DOT net
Applied Data Systems
www.applieddata.net
An ISO 9001:2000 Registered Company
Microsoft WEP Gold-level Member
.
- Follow-Ups:
- Re: Real Time sharing of data between WinCE systems?
- From: <ctacke/>
- Re: Real Time sharing of data between WinCE systems?
- References:
- Real Time sharing of data between WinCE systems?
- From: Martin Hughes
- Re: Real Time sharing of data between WinCE systems?
- From: Bruce Eitman [eMVP]
- Re: Real Time sharing of data between WinCE systems?
- From: Martin Hughes
- Re: Real Time sharing of data between WinCE systems?
- From: <ctacke/>
- Re: Real Time sharing of data between WinCE systems?
- From: Martin Hughes
- Real Time sharing of data between WinCE systems?
- Prev by Date: Re: Real Time sharing of data between WinCE systems?
- Next by Date: Re: SNTP does not sync continuously
- Previous by thread: Re: Real Time sharing of data between WinCE systems?
- Next by thread: Re: Real Time sharing of data between WinCE systems?
- Index(es):
Relevant Pages
|
