2.0 Discussion: Units, sensor types and protocol

[Zeph]

@hek said:

S_RGBW - RGBW Light
V_STATUS - 1 - turn on, 0 = turn off
V_R_PERCENTAGE - Red component % <int>
V_G_PERCENTAGE - Green component % <int>
V_B_PERCENTAGE - Blue component % <int>
V_W_PERCENTAGE - White component % <int>
V_WATT - Watt <int>
V_WATT_MAX - Max watt value
V_WATT_MIN - Min watt value
V_WATT_AVERAGE - Min watt value
V_WATT_RESET - Reset max/min values

One of the areas where the spec is very unclear is when a variable is writable and where it's only reportable (read only).

For example, can I set the watts to 20 above (or for S_DIMMABLE) in order to tell the light how much power I want it to use? Seems like a valuable option. How am I supposed to know?

What if we made the write/report/trigger function explicit:

S_RGBW - RGBW Light

W_STATUS - 1 - turn on (100%), 0 = turn off (0%)
W_R_PERCENTAGE - Red component % <int>
W_G_PERCENTAGE - Green component % <int>
W_B_PERCENTAGE - Blue component % <int>
W_W_PERCENTAGE - White component % <int>
R_WATT - Watt <int> - current instantaneous or short term average value
R_WATT_MAX - Max watt value since last reset
R_WATT_MIN - Min watt value since last reset
R_WATT_AVERAGE - Min watt value since last reset
T_WATT_RESET - Reset max/min/avg value

W variables can be written to; the current value can also be queried
R variables can only be reported (automatically or by query)
T variables are triggers, writing to them triggers some action

This gives guidance to both the sketch writer for the node, as well the controller adapter writer in knowing what they can do with each variable a node presents.

The actual numeric values for R, W and T codes could be interspersed or non-overlapping ranges could be reserved for each (eg: 1-100 for R, 101-200 for W and 201-255 for T)

[Damme]

@Zeph it all depends on how skilled programmer and how nerdy you are. if you want to set a lamp power with V_WATT great, thats nerdy! but in not, just dont read any thing from v_watt. .. there is no such thing as a read only variable, all depends on if you listen to incoming messages of that type or not.... I think you over-think this a bit. The atmega328 is a rather small mcu and wont be able to magically do tons of stuff. how to know what is what, well every home automation system should have a manual :) Write it down.

[Zeph]

@John

I can see a case for making HSB the norm.

Think of light types like a class heirarchy, with added functionality

S_BINARY

V_STATUS (1=100%, 0 =0%)

S_DIMMABLE

V_STATUS (1=100%, 0 =0%)
V_PERCENTAGE (0.0% - 100.0%)

S_HSB

V_STATUS (1=100%, 0 =0%)
V_PERCENTAGE (0.0% - 100.0%)
V_HUE (0.0 - 360.0)
V_SATURATION (0.0% - 100.0%)

If you set V_STATUS to 0, or V_PERCENTAGE to 0%, any of these lights turn fully off.
If you set V_PERCENTAGE to 100%, S_DIMMABLE will go to 100% (V_STATUS=1)
and S_HSV will go to 100%, in the current hue and saturation
If you set V_PERCENTAGE to 50%, likewise.

I think one could make the case that it's more human compatible to go to "yellow, 25%" than to figure out what the RGB values would be. (The user interface could translate yellow to a hue number)

One aspect HSB is that there are a couple of ways of associating colors with angles, so we would need to specify which is our standard, so 40 degrees is the same hue for all nodes. I like the rainbow style.

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@hek
I do also get the point that HSB -> RGB conversions could be done on the controller, passing the lower level RGB values to the node. There is an attraction to that as well.

This cannot be fully resolved without also considering the question of light curves or gamma factors, which has been raised. The controller needs to know whether or not the node implements light curves for RGB channels, so it can avoid doing that twice; and also it in the changes how the controller should convert HSB to RGB (the stock conversions assume RGB are linear).

[Zeph]

@Damme said:

Write it down

That's what I'm trying to do.

We could CLEARLY write down that V_WATT is intended only to report values and cannot be set, while V_RESET is a trigger, and V_R_PERCENTAGE is settable - so different implementors don't make different and incompatible guesses about what these mean.

We do not want the situation where one sketch writer interprets V_WATT to be a way to control how much power the lamp will use and another sketch write interprets it as reporting only. And then controller interface writers also guess differently about what it means. That's chaos.

One step in that direction would be naming them according to the intention - writable, reportable, or trigger.

I've done a LOT of implementing from specifications, as many others have. Having a clear specification that avoids huge ambiguities (is this something you set or something that reports is huge) is not over-thinking - it pays off big time.

[Yveaux]

@hek said:

Crazy

You didn't dare posting a red version, did you? :dancer:

[John]

@Zeph

I can see a case for making HSB the norm.

I'm not ;). it is just a possible addition of possible value types to the S_RGBW type and if not possible like you stated a S_HSB and to keep clarity V_PERCENTAGE should then be V_BRIGHTNESS. Or both percentages (not possible) or both naming as it is.

One aspect HSB is that there are a couple of ways of associating colors with angles

Off topic, which ones? i only know one, are you sure your not mixing HSB with HSL?

On topic:
I'm fine with only sending RGB if HSB ain't possible to be combined with S_RGBW or added with S_HSB/S_HSV if it is thought of as a logical addition.

[Zeph]

@John
You are probably way ahead of me in terms of formal color spaces. I'm just a color user.

I like using a modified Hue, such the the "rainbow" described here:

https://github.com/FastLED/FastLED/wiki/FastLED-HSV-Colors

[John]

@zeph said

You are probably way ahead of me in terms of formal color spaces

Not really, i'm no color expert, But did a lot with colors lately because i use this to influence our living environment

Ok got it, Hue with rainbow style is variable due to the amount of colors (real life circumstance like angel etc) on that page an almost perfect rainbow angle and lighting situation is used.

I agree with you, but that's user implementation on the hardware, and something mysensors can not control. You would still need the HSB parameters ;) The implementation of rainbow or spectrum should be done on the controller<->end device side and the end user should know about it (or at least the developer of that specific controller/hardware implementation), not protocol based, because the parameters are still the same.

[epierre]

@Hek globally I don't understand the min/max/average, are they managed by the sensor or the controller ? if it is the sensor in case of reboot it should get it back from the gateway/controller and should be resettable maybe to have a year/month/week/day min/max. For me that should be controller side to handle this logic...

Now for my favorite playground ;-) it needs the calibration value clearly first, then for the discussion some projects (AirPi) avoid the calibration pitfall by sending back the voltage... If we want to have a concentration value from the sensor that is ok.

 S_AIR_QUALITY - Air Quality Sensor
 V_LEVEL - ? We need to describe this better
 V_LEVEL_RESET - Reset max/min value

@hek Hmm.. Soil Moisture.. I have no idea how to represent this. Help me! The ebay sensors we're using isn't super accurate and comes uncalibrated.

@damme   Hmm... V_Moisture, (relative) 0-255 / 0-100% / True | False

On both I agree, I have some imaginatronix and yes you need a margin of error... but when it rains it rains... this is where a calibration value will be usefull at least to have several sensors showing the same value at the same environment time... I you want a logic then the true false can be good but not enough... on my imagitronix I have an empty value of 20% and a watered value of 100%, sometimes after the rain it is 80%..., where would be the limit ?

Also, I am thinking of a leaf wetness (we had a lot here this year... and diseases that goes with it) that could be mapped to soil sensors [Article on values(http://www.decagon.com/education/do-you-measure-leaf-wetness/)

[hek]

@epierre said:

globally I don't understand the min/max/average, are they managed by the sensor or the controller ? if it is the sensor in case of reboot it should get it back from the gateway/controller and should be resettable maybe to have a year/month/week/day min/max. For me that should be controller side to handle this logic...

The MAX/MIN/AVERAGE are optional to use. My idea was that sensors would manage them. They can choose to store it in eeprom or throw away values when reboot occurs.
The idea originates from GUST for wind which really is a max value over a certain time. This is just a generalization.
Usecase: Sensor might not report every wind value to controller but just every 10 minute. But internally it can calculate average/max/min for every 10 seconds without pushing this.

[Rasmus Eneman]

Please leave HSV/HSL to the controller. Why complicate the node more that necessary?
Using LEVEL would be good, 8 bit per color is good, it's also super easy for the node to scale down if only supporting 7 or 6 bits and it's perfect for those digital LED strips.

Please have a pure RGB without W, most strips and RGB leds don't have a W diode so that would need to be simulated with different result in different nodes.

[John]

@Rasmus-Eneman

Please leave HSV/HSL to the controller. Why complicate the node more that necessary?

That's why i asked for an addition if it would over complicate stuff (and if there is room for it) ;). And well, yeah you're right, S_RGBW with HSB would be complicating things more mixing capabilities with the node naming. There is always S_CUSTOM with V_VAR_1,V_VAR_2,V_VAR_3 combination.

I agree with leaving out the W. But could be a nice addition for those non calibrated fixtures where you have to supply calibrated values in the node to get "proper" white levels.

[epierre]

@hek ok I agree. Can we have too an alert that could be sent back to the gateway, or like an armed mode for the air sensors ?

Today, one of my daughter broke a bottle of perfume, saturating the air and making the sensor go to its max. Even if the sensor is not calibrated, on some kind that (IMHO) must raise an alert for I cannot say infinite or over the maximum value...

[Yveaux]

@epierre In 1.4 a binary represetation of a float value can be exchanged with the library. This allows to report e.g. + or - infinite where normally floating point values are sent. Maybe this will serve your purpose?

[Zeph]

If you do have a strip with RGB and W LEDs (rare), this can be handled as an RGB light and a DIMMER.

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A lot of our discussions really hinge on how much smarts to put where in the architecture. My overall philosophy would be to keep the node simple and move functionality to it only when the same thing cannot be easily done centrally. Reasons to move smarts into a node could include:

• Uses local calibration that central doesn't have
• Needs updating more often than reports go to central (eg: wind max)
• Timing, eg: safety features that need to act fast
• Reliability of data links, eg: safety features that should not depend on RF robustness
• Providing some logically consistent interface available to all controllers
• Providing some functionality which cannot be as easily implemented in a controller (eg: closed source)

The latter two would be one-off custom coding at this time, tho @hek has mentioned the idea of pushing some rules down to the node level in a more automated way someday.

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This probably argues more for using RGB rather than HSV at the node level. What I liked about the HSB was the unification of on/off, dimmable, and HSB functionality as a nested set of expanding functionality. So a script or rule that sets the brightness could work on a DIMMABLE or a HSB light by setting the V_PERCENTAGE value (or V_BRIGHTNESS as someone suggested). But that could be done at the central level.

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I've used the term "central" because I still have the vision that a "hub" or "gateway" could implement some features, rather than having the smarts only in the controller or in the sensactuator nodes. So for example, it could be possible for the gateway to convert HSB to RGB such that the controller doesn't have to implement it. I know that approach is not currently popular so you don't need to register general disapproval. This will either come to seem a worthwhile additional open in coming years or not.

[Zeph]

@epierre said:

Can we have too an alert that could be sent back to the gateway, or like an armed mode for the air sensors ?

Today, one of my daughter broke a bottle of perfume, saturating the air and making the sensor go to its max. Even if the sensor is not calibrated, on some kind that (IMHO) must raise an alert for I cannot say infinite or over the maximum value...

Let's not bring infinity into this...

How about just returning "the maximum reportable value" (finite). If the node is capable of detecting "above measurable" conditions, have it define the "maximum reportable" as 1 higher than it's internal "maximum measurable".

The idea is to keep a simple scale of results, where for example we can consistently compute "max/min over 24 hours", or set a trigger on "value >= threshold" without needing to deal with infinity math. Some controller software may not have any concept of infinity, so using it brings in unnecessary incompatibilities.

This allows the controller to define the alert as it wishes. For example, suppose a sensor reports uncalibrated values of 25 to 173, and the node uses 174 for a detected "over-range". The controller can implement a trigger or event at "value > 160" to test for high values (without having to test for infinite values too). Or it could test for "value >=174" if it specifically wants to test for overrange (which could be way over the max measured value or just barely above it).

[hek]

@epierre said:

Today, one of my daughter broke a bottle of perfume, saturating the air and making the sensor go to its max. Even if the sensor is not calibrated, on some kind that (IMHO) must raise an alert for I cannot say infinite or over the maximum value...

LOL

[epierre]

@Zeph I don't share the same view, since we allow logic in the sensor for min/max interval, why not doing it too for the gas level ? all the more that the limit of the sensor is not a "business logic" but an internal logic linked by the physical capacity of the sensor itself (and which varies with each sensor type...).

My point was more that if you monitor LPG NO2 / NO3 or smoke that could be really harmfull we should provide safeguards anyway... not a big deal, more a safety net...

[hek]

Ok,

I will change create two device-types S_RGB and S_RGBW and use a level instead of percentage for each color component (0-255).

[epierre]

For my sound sketch :

S_SOUND - Sound sensor

V_LEVEL - sound level in db
V_LEVEL_MAX - Max sound level
V_LEVEL_MIN - Min sound level
V_LEVEL_AVERAGE - Average sound level
V_LEVEL_RESET - Reset max/min value