On Jan 8, 4:40=A0am, "anex" <anex.stormrider@n_o_s_p_a_m.gmail.com>
wrote:
> Hi,
>
> I want to try and develop a network of micro-controllers that can interac=
t
> and share data with each other in real time and coordinate together to
> perform a function. I want to use a wireless mode of networking and not t=
he
> traditional wired CAN network. However I need to convince my supervisor o=
f
> the possible applications it may have and its advantages over the wired
> version. I am stuck at this point and it seems I dont have any use of the
> concept.
>
> Can anyone out of their experience suggest any possible application to su=
ch
> a network. I have heard about CAN being used in cars to coordinate
> different control units, but I wanted something more domestic and looking
> for small push to get some ideas rolling in my own head.
>
> thanks
>
> ---------------------------------------
> Posted throughhttp://www.EmbeddedRelated.com
> On 14/01/12 23:58, Bob wrote:
>> Sure, the easy path is to give up, but that doesn't help develop
>> anything new. If the OP wants to go wireless, why not let him try.
>>
>> Apparently, "engineers" have developed some quite successful wireless
>> technologies. I guess if John Logie Baird had been on the internet,
>> some people would tell him he was crazy, and should stick to wires.
>>
>> Perhaps having spent time working on mobile phones, DECT etc, I am
>> not quite so scared of wireless as you are. As you say, there is a
>> market for wireless devices, maybe some engineers will be smart
>> enough to work out the solutions.
>
> If wireless the best choice for the problem at hand, then use wireless.
> But as the OP described the situation, they could deal with it using
> wired connections, and that's what the boss wanted (presumably the boss
> knows more than the OP, or has taken advice from people who do). So
> wired networking is good engineering - it solves the problem reliably in
> a way that satisfies the customer. Using wireless networking may or may
> not be an alternative - good engineering practice is to consider it, but
> only to use it if there are clear advantages.
>
> I think you are mixing up "inventions" and "engineering". When you know
> a good way to achieve the required results, then it is simply
> unprofessional to waste time and money on something unknown unless you
> have good reason to believe it will be much better in the end.
My take on the OP is NIH.
Not Invented Here.
He wants his ideas to be the "profitable" idea.
don
Reply by David Brown●January 15, 20122012-01-15
On 14/01/12 23:58, Bob wrote:
> Sure, the easy path is to give up, but that doesn't help develop
> anything new. If the OP wants to go wireless, why not let him try.
>
> Apparently, "engineers" have developed some quite successful wireless
> technologies. I guess if John Logie Baird had been on the internet,
> some people would tell him he was crazy, and should stick to wires.
>
> Perhaps having spent time working on mobile phones, DECT etc, I am
> not quite so scared of wireless as you are. As you say, there is a
> market for wireless devices, maybe some engineers will be smart
> enough to work out the solutions.
If wireless the best choice for the problem at hand, then use wireless.
But as the OP described the situation, they could deal with it using
wired connections, and that's what the boss wanted (presumably the boss
knows more than the OP, or has taken advice from people who do). So
wired networking is good engineering - it solves the problem reliably in
a way that satisfies the customer. Using wireless networking may or may
not be an alternative - good engineering practice is to consider it, but
only to use it if there are clear advantages.
I think you are mixing up "inventions" and "engineering". When you know
a good way to achieve the required results, then it is simply
unprofessional to waste time and money on something unknown unless you
have good reason to believe it will be much better in the end.
Reply by ●January 15, 20122012-01-15
On Sat, 14 Jan 2012 14:58:30 -0800 (PST), Bob
<bobcousins42@googlemail.com> wrote:
>Sure, the easy path is to give up, but that doesn't help develop anything new.
>If the OP wants to go wireless, why not let him try.
The problem is the great influx of people with only digital logic
background trying to do wireless things.
Unfortunately, the learning curve may be too steep for real world
non-trivial wired digital communication (which essentially deals with
analog phenomenons) not to mention any non-line-of sight wireless
communication systems.
>Apparently, "engineers" have developed some quite successful wireless technologies. I guess if John Logie Baird had been on the internet, some people would tell him he was crazy, and should stick to wires.
>
>Perhaps having spent time working on mobile phones, DECT etc,
>I am not quite so scared of wireless as you are.
>As you say, there is a market for wireless devices,
>maybe some engineers will be smart enough to work out the solutions.
Different wireless users groups have quite different expectations for
the reliability of communication.
For instance, some amateur radio operators are satisfied if they can
utilize some special propagation phenomenon that might work 1 % of the
time (or even once in a lifetime).
A person marketing some wireless gadgets are usually satisfied with
30-70 % reliability, so that in a marketing situation, the system
would appear to work (and if it fails to work in some are marketing
situation, it is still easy to find some excuses :-).
Any serious wireless communication system is expected to work 99 % or
even 99.99 % of the time. Unfortunately. the system cost tend to go up
by one decade, for each nine added to the reliability requirement.
Reply by Bob●January 14, 20122012-01-14
Sure, the easy path is to give up, but that doesn't help develop anything new. If the OP wants to go wireless, why not let him try.
Apparently, "engineers" have developed some quite successful wireless technologies. I guess if John Logie Baird had been on the internet, some people would tell him he was crazy, and should stick to wires.
Perhaps having spent time working on mobile phones, DECT etc, I am not quite so scared of wireless as you are. As you say, there is a market for wireless devices, maybe some engineers will be smart enough to work out the solutions.
Reply by ●January 13, 20122012-01-13
On Fri, 13 Jan 2012 10:12:12 +0100, David Brown
<david@westcontrol.removethisbit.com> wrote:
>On 12/01/2012 19:52, Sink0 wrote:
>> As far as i could understand, OP just need a isochronous network. For sure
>> he does not need a lot of reliability on the data delivered, but just a
>> strict timing.
>
>Wireless does not give you any reliability about data delivering /or/
>timing. You must build your wireless system with the assumption that it
>often won't work at all, and certainly that telegrams will get delayed,
>lost, re-transmitted, corrupted, etc.
Except for really trivial communication cases, you either get reliable
but not realtime transfers or alternatively realtime but unreliable
communication, but you can not get both reliable and realtime at the
same time. This applies to both wired as wireless environments.
In a broadcast (one way) system (e.g. GPS downlink), the timing is
quite exact, only slightly varying due to the varying speed of light
in a medium (troposphere and ionosphere).
Reply by David Brown●January 13, 20122012-01-13
On 13/01/2012 13:37, Sink0 wrote:
>> On 13/01/2012 12:26, Sink0 wrote:
>>
>> We are talking about CAN, and not video, because the OP asked about
>> real-time networking and data sharing between microcontrollers using
>> wireless networking instead of CAN.
>>
>> I am not sure why you brought video into the discussion.
>>
>> Maybe there has been some mix-up of threads somewhere. I see that both
>> you and the OP posted through a website rather than using the
>> comp.arch.embedded newsgroup directly - maybe you've mixed something up
>> with other discussions elsewhere on that website?
>>
>>
>>
>
> I guess i got confused here. I thought that the third message was sent by
> OP. The one talking about modular matrix displays. But i am wrong. Sorry my
> mistake.
>
> Cya
>
Well, when people use meaningless pseudonyms and silly names, it's easy
to get mixed up. There are occasional good reasons for anonymity in
Usenet groups or other discussion forums (I know some manufacturers and
tool developers haunt this group under pseudonyms, for example - if they
were open about their names and employers then it could hinder free
discussions). But mostly such names just means no one knows who is
talking to whom.
Reply by John Mianowski●January 13, 20122012-01-13
On Jan 8, 4:40=A0am, "anex" <anex.stormrider@n_o_s_p_a_m.gmail.com>
wrote:
> Hi,
>
> I want to try and develop a network of micro-controllers that can interac=
t
> and share data with each other in real time and coordinate together to
> perform a function. I want to use a wireless mode of networking and not t=
he
> traditional wired CAN network. However I need to convince my supervisor o=
f
> the possible applications it may have and its advantages over the wired
> version. I am stuck at this point and it seems I dont have any use of the
> concept.
>
> Can anyone out of their experience suggest any possible application to su=
ch
> a network. I have heard about CAN being used in cars to coordinate
> different control units, but I wanted something more domestic and looking
> for small push to get some ideas rolling in my own head.
>
> thanks
>
> ---------------------------------------
> Posted throughhttp://www.EmbeddedRelated.com
This approach is what's called, "A solution in search of a problem".
It almost never ends any way other than ugly, expensive, unreliable,
expensive, or an utter failure, not to mention expensive. Did I
mention "expensive"? Good luck becoming a rare exception!
Key points:
"..I need to convince my supervisor of the possible applications..." -
In other words, there are no defined needs.
"...I dont have any use of the concept..." - Nor do your customer(s),
who are expected to actually pay for the product.
Start with your (customers') needs & requirements. Work from there.
Search for the simplest & most robust solutions that solve the actual
problems. It may very well turn out that wireless is the best
solution. It also may not. It's not a very sexy process, but it
improves your odds of ending up with a viable product.
Starting with a solution, & trying to shoehorn problems into it, is
what I call "Painting yourself into a corner". Once you've made a
particular choice (i.e. to paint the floor next to the door first,
etc.) it can become very difficult to adapt when the REAL problems
that actually do need solving pop up.
Reply by Sink0●January 13, 20122012-01-13
>On 13/01/2012 12:26, Sink0 wrote:
>
>We are talking about CAN, and not video, because the OP asked about
>real-time networking and data sharing between microcontrollers using
>wireless networking instead of CAN.
>
>I am not sure why you brought video into the discussion.
>
>Maybe there has been some mix-up of threads somewhere. I see that both
>you and the OP posted through a website rather than using the
>comp.arch.embedded newsgroup directly - maybe you've mixed something up
>with other discussions elsewhere on that website?
>
>
>
I guess i got confused here. I thought that the third message was sent by
OP. The one talking about modular matrix displays. But i am wrong. Sorry my
mistake.
Cya
---------------------------------------
Posted through http://www.EmbeddedRelated.com
Reply by David Brown●January 13, 20122012-01-13
On 13/01/2012 12:26, Sink0 wrote:
>>
>> Wireless does not give you any reliability about data delivering /or/
>> timing. You must build your wireless system with the assumption that it
>> often won't work at all, and certainly that telegrams will get delayed,
>> lost, re-transmitted, corrupted, etc.
>>
>>
>
> I agree with all your opinions, but you can for sure get a very good timing
> on wireless video transmiting if you give up data integrity, and that is
> the whole point of working with isochronous transmission. You just dont
> check the data as in general the user wont be able to notice a wrong bit or
> even a whole dead frame if we are talking abou a 60hz refresh rate. That
> would work as a digital tv or any other digital video broadcast. Actually
> even working on wires, checking data integrity on your video can kill you
> whole application as you can not assure any timing. Thats why it is always
> isochronous transmission.
>
> Finally i dont know why you guys are talking about CAN... CAN is not meant
> to transmit any sort of video.. considering a 60Hz rate, with 3 bits
> collors and 2000 "pixels" (20x100) we gor 360kbps, and that is pretty close
> to CAN limit considering overhead.
>
We are talking about CAN, and not video, because the OP asked about
real-time networking and data sharing between microcontrollers using
wireless networking instead of CAN.
I am not sure why you brought video into the discussion.
Maybe there has been some mix-up of threads somewhere. I see that both
you and the OP posted through a website rather than using the
comp.arch.embedded newsgroup directly - maybe you've mixed something up
with other discussions elsewhere on that website?