On Fri, 29 Sep 2017 16:34:18 +0200, Axel Berger wrote:

> This leads to two questions: What programming language should I use? I
> haven't done any real programming in ages and the languages I used to
> know are obsolete. I have done (or rather used) a simple test routine
> for my solenoid output card in python, which seems to be the accepted
> standard for the pi, but I don't like it.

A lot of low level driver stuff for breakout boards is for Python, my
current project is using a couple of those and thus is being written
in Python. I don't like it either. It's probably my lack of knowledge
about the very basics of how Python expects you to construct your
program and how to properly organise the source code file structure.
I've yet to find a good, clear, guide/tutorial on those aspects.

> The second problem is hardware. The ducts leading to my current
> thermostats are strictly a star configuration, so one wire is not the
> obvious choice.

I wouldn't write off 1-wire, it can do star. IIRC star and parasitic
power don't play nicely. There are some pretty good guides on the
limitations and how to configure/build 1-Wire networks out there. I
think they are on the Dallas site.

Or there is the Embeded Systems OW Server that has three 1-Wire
ports, fairly sure they are independant of each other.

> What ohter kinds of sensors are there and how can I connect at least 8
> to the Pi? Part of the GPIO, 8 output pins, is already taken by the
> solenoid card.

Yuk, have a look at the 1-Wire DS2408 8 channel addressable switch.
I'm using one to monitor the state of some mains relays as you can
read the state of the output pins not just an internal register You
can read those as well though. You can of course switch things on/off
and as you can read the state of the of pins get feedback that at
least the switch in the chip has
operated.

https://www.maximintegrated.com/en/products/digital/memory-products/DS
2408.html

I see that there are relay boards controlled by this chip on eBay but
the ones I briefly saw on a google results page were £35 so not
exactly cheap.

--
Cheers
Dave.

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