About that pause when reading the 1-wire temp sensors...
I'm somewhat new to MH, 1-wire, and perl, so someone please correct me if anything I say here isn't quite right.
When dealing with parasitic powered DS1820 sensors it's necessary to enable a "strong pullup" after sending the convert command to the sensor, so that it has sufficient current to convert the temperature. This lasts about 600ms. After that, the temperature can be read from the sensor's scratch pad. But during the 600ms time it takes to convert the temperature, MH sleeps, thus the pause.
In non-parasite mode, without the strong pullup, couldn't MH go off and do other things during that conversion period? Even with parasitic powered sensors and the strong pullup, the only restriction would be that no other 1-wire activity could happen while the strong pullup is active. The temperature function could be divided into 2 functions, one to command the conversion and the other to read the temperature from the scratchpad. In fact, using the SKIP ROM (CCh) command all DS1820s on the bus could be commanded to convert the temperature at once, and then they could be read individually sometime later.
If I find some time I'll try and play around with this some, but I thought I'd throw it out there and see if anyone had any ideas on the topic.
Nigel Titley <email@example.com> wrote:
Don Wilde, Ph.D. wrote:
> I was looking at the link-TH at (www.ibuttonlink.com). It appears to
> have internal polling for temperature sensors and voltage sensors.
> Has anyone tried this? If true, it would eliminate the pause in MH
> when reading these 1-wire devices.
Yes it does, and yes it should. Of course you'd need to write the
interface to MH, which is something that I'm going to get around to at
some point if someone else doesn't. One advantage of selling the stuff
is that I can play with it (of course the disadvantage of selling the
stuff is that I now don't have *time* to play with it).
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