owlib does have support for that kind of device -- (multiple buses) -- The
DS2482-800 is a good example. It has one "port" and multiple buses. The
port gets locked for just the message (e.g. serial communication) and the
individual 1-wire bus and slave gets locked for the 1-wire "conversation".
Each of those buses can have independent conversations (e.g. do temperature
conversions independently).
On Tue, Aug 1, 2017 at 11:24 AM, Jan Kandziora <j...@gmx.de> wrote:
> Am 01.08.2017 um 16:01 schrieb Alastair D'Silva:
> > Hi folks,
> >
> > I'm currently designing an open-hardware 32 port 1wire bus master for
> part
> > of my home automation system, and would like your input.
> >
> > The design is based around an STM32F412ZG microcontroller, with MOSFET
> > active pullups & drive transistors. It will present as a hat for the
> Orange
> > Pi Prime (other Pis may also fit). My plan is to connect over the serial
> > port, but I've also wired through I2C & SPI just in case.
> >
> A hat employing standard connectors is going to be more useful to
> average users. This limits the number of channels because of the size of
> the hat.
>
> And nearly no one would need 32 channels. The 8 channels the DS2482-800
> offers are already too much for most applications.
>
> What would be incredibly useful is a chip that does have separated RX
> and TX lines for each channel so one could use optocouples for totally
> isolated onewires. People using Onewire for building a weather station
> will love you for such a thing. Your hat should employ these, as well as
> an optional isolating DC-DC converter!
>
> What would be also useful is a device that offloads e.g. the search
> algorithm as the DS2490 does. That chip is now unavailable outside of
> the DS9490U device.
>
>
> > I'm currently considering how the device should present to OWlib:
> >
> I found it most useful if you wrote a w1 kernel driver for it instead,
> so one could also use the DS28E17 Onewire-to-I²C bridge with your chip.
>
>
> > Option 1: Maintain an internal hashtable mapping devices to ports, and
> > present as a single bus master. This has the downside of limiting the
> > potential number of devices, as well as monopolising all the buses during
> > long events, such as a firmware update. This would be annoying, as my
> light
> > switches won't respond across the whole house if I have to update the
> > firmware on any device.
> >
> > Option 2: Present as a single multi-bus master. I'm not sure if OWlib has
> > such a concept, if not, there may be significant infrastructure work
> > required. If it does, great, as hopefully OWlib will keep track of which
> bus
> > a device belongs to.
> >
> Just look at the DS2482-800 host adapter code.
>
>
> > Option 3: Present as many bus-masters. I think this would be a reasonable
> > solution, as other buses should continue to operate even if one is
> > monopolised by a firmware update. In this situation, only a single room
> will
> > stop responding, rather than the whole house.
> >
> On the OWFS level? Better not, it would make the configuration awfully
> complicated and require an awful lot of work.
>
>
> >
> > PS. Would it be possible to get my current work reviewed? I'm not quite
> > ready to push it upstream, but it would be good to know early if there is
> > anything there that would prevent it from being merged. My repo is here:
> > https://github.com/InfernoEmbedded/owfs/tree/infernoembedded
> >
> Please do not use the same source file for both your upcoming host and
> your current LED controller and relay boards.
>
>
> If you are happy with your current devices **and have them tested
> against the current version of owfs**, prepare a patch and I will push
> it into master. You are the only one who can test it anyway as long
> noone else has this hardware.
>
> Kind regards
>
> Jan
>
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