Re: Simat 1 wire Hubs

[Jon Payne <jgpayne@xxxxxxxxxxxxxx>]

Yes, 750ms at 9-bit resolution, and on my TINI it takes almost 1.5
seconds because there are other threads running (although I need to
re-measure because I've just changed to timer based rather than thread
based so it should speed up a bit).

Another issue I have with the default 1-wire library implementation is that
it is just implemented as a delay, so to poll all temperature sensors I do
this at the moment:
1. lock 1-wire bus
2. select next temperature sensor
3. set temp conversion going
4. delay for 750ms
5. read temperature
6. deselect temperature sensor (close the path to the device)
7. release 1-wire bus (to let other's use the bus)
8. goto 1

So for n sensors it takes n * ( time to open path +750ms + time to close
path) at best.

Whereas I could do:
1. for all temperature sensors
1.1 lock 1-wire bus
1.2 select next temperature sensor
1.3 start temp conversion going
1.4 release 1-wire bus
2. delay for 750ms (although this could be optimised somewhat)
3. for all temperature sensors
3.1 lock 1-wire bus
3.2 select next temperature sensor
3.3 read temperature
3.4 release 1-wire bus

Which would be faster. And then if other sensors need polling I should
really optimise it according to their location on the bus so the same path
isn't opened multiple times when it doesn't need to be.

Hmmm... all a bit more complicated than I wanted...

----- Original Message ----
From: Frank Mc Alinden <frankmc@xxxxxxx>
To: ukha_d@xxxxxxx
Sent: Tuesday, 22 May, 2007 7:33:40 AM
Subject: Re: [ukha_d] Simat 1 wire Hubs


Hi Jon

>now I'm thinking that it slows down the 1-wire network too much for my
>purposes.

Yeah i noticed that the branches get polled.....Im going to put moisture
sensors and any outdoor temp sensors on the Hub  and my Ibuttons on the
main
trunk along with the lcd that i have just ordered.. Dont for get though Jon
it take approx 700mSEC to read a dallas temp sensor this delay is not due
to
the HUB.....Luckily my room temp sensors connect to my Probe system so that
will reduce the scan time a bit.....I,ll have  a play with the lcd
connected
to the HUB to see what sort of delays i get.......

Frank


----- Original Message -----
From: "Jon Payne" <jgpayne@xxxxxxx>
To: <ukha_d@xxxxxxx>
Sent: Monday, May 21, 2007 10:08 PM
Subject: Re: [ukha_d] Simat 1 wire Hubs


> Yep, same as you really I dusted it off about 1 year ago... now I'm
> thinking that it slows down the 1-wire network too much for my
purposes.
> With a couple of LCDs, a few ibutons, DS2406's, and about 8
temperature
> sensors it takes 10 seconds to scan for the presence of devices on the
> network, during which the network is locked out, before I've even
polled
> existing devices: about 20 seconds for temperature sensors (with most
on
> the same branch). This means for example a message needing to be
displayed
> on an LCD is delayed for too long.
>
> ----- Original Message ----
> From: Frank Mc Alinden <frankmc@xxxxxxx>
> To: ukha_d@xxxxxxx
> Sent: Monday, 21 May, 2007 12:30:04 PM
> Subject: [ukha_d] Simat 1 wire Hubs
>
>
> Hi Guys
>
> Just got round to trying out my  Simat 1 wire hubs...Cant believe they
> have
> been gathering dust that long  i think  that  we  had a bulk buy back
> around
> July/sept  2002 ;-)...
> Anyone on the list who got one using theirs ;-)
>
> Frank
> www.armaghelectrical.com.au
>
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