M950 to add servo control

moth4017

M950 add the option so a sevo motor can be control for options like this
https://github.com/vitals78/Flap-controlled-CPAP

T3P3Tony

@moth4017 so this would be a hybrid "fan" where its the fan + a servo motor as a single addressable device?

whats the relationship between the ream fan speed PWM % and this composite fan flap%? Presumably the CPAP fan is not just set to 100% and the flab varied exclusively (or is it?)

moth4017

@T3P3Tony fan speed stays the same the flap varies the output 0 to 100%

T3P3Tony

@moth4017 Ok, when does the fan turn on/off? Is that a separate command or just when the "composite fan" is set above 0?

moth4017

@T3P3Tony
cpap/fan , controlled via A fan output,
servo Controlled via A fan output
Flap homing via digital input

required 2 fan outputs and 1 input in total

T3P3Tony

@moth4017 ok, but what would the configuration command look like and the control.command?

Presumably M106 for control?

jay_s_uk

@T3P3Tony I would suggest M106 for control, with M950 being able to set a minimum and maximum servo angle for 0 and 100%

moth4017

@jay_s_uk
so M950 set min & max angel
and
M106 still be 0 to 100%

jay_s_uk

@moth4017 yea exactly, so M106 is able to extrapolate an angle for an M106 percentage based on the min and max in M950

T3P3Tony

@jay_s_uk @moth4017 so M106 S0 sets the servo and the fan to 0, M106 S0.1 sets the fan to 100% and the servo to 10% ?

jay_s_uk

@T3P3Tony yes, something like that. maybe with the ability to set the % for the fan you want to use.
e.g.
M950 S0 "servo+fan" K10:90 U90
where K is the min/max angle and U is the fan percentage
Its a bit tight on what letters are available on M950 so I had to reuse a couple

T3P3Tony

@jay_s_uk ok the numbers would be for @dc42 to decide but I get the general idea.

Are there any other examples of these sorts of "composite" devices that come to mind?

jay_s_uk

@T3P3Tony none that come to mind that I've seen

T3P3Tony

@jay_s_uk was hoping for some nice generalisation of the concept. Oh well.

jay_s_uk

@T3P3Tony maybe its a bit like "if you build it they will come"
I don't keep track of most of the cooling options though TBH as I'm mostly CPAP now

moth4017

@jay_s_uk @T3P3Tony I have 2 applications for this cooling and venting, I sometimes need to vent the printer chamber through a carbon filter because of the fumes ,but can only do this when the chamber is cool enough for the activated carbon, I'm sure there will be other uses, as always I

T3P3Tony

@moth4017 that feels like something that can be done with metagcode already (,the chamber venting if the chamber sensor is below a certain temperature)

moth4017

@T3P3Tony i still need to control a vent/solenoid / servo as my chamber is sealed , i just thought it would be away to kill 2 birds one stone

T3P3Tony

@moth4017 This is logged in GitHub now:
https://github.com/Duet3D/RepRapFirmware/issues/1092

T3P3 created this issue in Duet3D/RepRapFirmware

open Allow support of composite Fans #1092

moth4017

@T3P3Tony thank you