OpenBeken SG90 servo control configuration guidance, Home Assistant integration?

Name: OpenBeken SG90 servo control configuration guidance, Home Assistant integration?
Uploaded: 2025-03-02T09:29:28+01:00
Description: Hi all. I've got a device (IR rx/tx) running OpenBeken, and I need to drive a servo with it. I can handle the pins and the soldering and all that, but I'm coming up short on configuration. I need to be able to set the angle (I don't care if it's 0~180, 0~1, 0~255, etc) and release the servo...

Question

Hi all. I've got a device (IR rx/tx) running OpenBeken, and I need to drive a servo with it. I can handle the pins and the soldering and all that, but I'm coming up short on configuration. I need to be able to set the angle (I don't care if it's 0~180, 0~1, 0~255, etc) and release the servo...

p.kaczmarek2 · Answer

Sure, it's a good idea. Let me try this out so we can figure out a config for you:

Handheld oscilloscope with signal graph and breadboard with electronic components.

@divadiow do you have any servos?

@insmod I think it may be a good time to clear up pwm frequency settings and maybe add them per pin, can you check out this PR? https://github.com/openshwprojects/OpenBK7231T_App/pull/1554 WIP

Added after 32 [minutes]:

Set required pin to PWM_ScriptOnly. Give it channel 20. Just to be sure, use my PR or wait for merge. Use autoexec.bat:


PWMFrequency 20

startDriver httpButtons

setButtonEnabled 0 1
setButtonLabel 0 "Set -90"
setButtonCommand 0 "setChannelFloat 20 5"

setButtonEnabled 1 1
setButtonLabel 1 "Set 0"
setButtonCommand 1 "setChannelFloat 20 3"

setButtonEnabled 2 1
setButtonLabel 2 "Set 90"
setButtonCommand 2 "setChannelFloat 20 1"

It works, more or less:

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.

insmod · Answer

>>21462196 LGTM for setting up frequency in pwm start, but i'm not sure about per channel frequency. Theoretically it's a good idea, but practically i've yet to encounter any device that would've required it.
And isn't array size of 16 for periods a little too big? Set it to 6 and use pwmIndex, not pin index to access it. (and what would happen now if pins 24 or 26 are selected? out-of-bounds?)

p.kaczmarek2 · Answer

Actually I have considered it again and I also decided that maybe for now I'll stop with what we have now. Per channel frequency can be added later when we'll have someone show up who really needs this setting.

For the use case from this topic, global frequency seems still fine.

Array is a placeholder, I'll check size in a moment

divadiow · Answer

Negative. I do not

CodeFaux · Answer

>>21462196

This is a good start. Thank you very much. It is working. I didn't have PWM_ScriptOnly but an update fixed that.

Is there a way I can set the script to release the servo automatically after ~2 sec or must I implement that myself? I need to release the servo so it doesn't overheat and melt if it's stuck, and so the user can adjust the control themselves if required. 'setChannelFloat 20 0' will release, but I need a pause while the servo moves.

p.kaczmarek2 · Answer

I'm not sure what you mean, are you asking how to make a delay? You can use delay_s within autoexec.bat script. Or are you asking how to entirely disable PWM? Well, I would assume that, for example, doing setPinRole to AlwaysLow or AlwaysHigh can do that, but PWM with 0 duty is the same as AlwaysLow...

Or maybe I am overthinking it and you just need to read:
https://github.com/openshwprojects/OpenBK7231T_App/blob/main/docs/autoexecExamples.md
and adjust:


alias disable_with_delay backlog cancelRepeatingEvent 123456; addRepeatingEventID 5 1 123456 setChannel 1 0

maybe into:


alias setOn setChannelFloat 20 0.2
alias setOff setChannelFloat 20 0
alias run_and_disable backlog setOn ; cancelRepeatingEvent 123456; addRepeatingEventID 5 1 123456 setOff

Or you can do the same in script...

I am creating multiplatform open source firmware (Tasmota replacement), right now supporting BK7231T, BK7231N, XR809, BL602, W800, W600, LN882H and soon supporting RTL and W701:
https://github.com/openshwprojects/OpenBK7231T
If you like my work, support me at: https://paypal.me/openshwprojects

Helpful post? Buy me a coffee.

CodeFaux · Answer

>>21463683

A servo forces its position to match PWM signal.

If you turn off PWM the servo releases and will let you turn it.

I need to stop sending PWM after ~2 sec, any time PWM is enabled.

Seems some modification of https://www.elektroda.com/rtvforum/topic4011890.html#20797236 should work.


// want to turn off PWM on CH20 after 2 seconds
// addRepeatingEvent   [IntervalSeconds][RepeatsOr-1][CommandToRun]
alias turn_off_after_time addRepeatingEvent 2 1 setChannel 20 0
// this should run turn_off_after_time every time that CH20 becomes not 0 but does nothing
addChangeHandler Channel20 != 0 turn_off_after_time

But it does not work. turn_off_after_time works, and addChangeHandler works, but channel 20 changes don't trigger the alias. Any suggestions?

p.kaczmarek2 · Answer

That change handler is called when a transition from 0 to non 0 value happens. It won't be called when CH20 transitions from non-zero to non-zero value.

I think you rather need:


alias turn_off_after_time addRepeatingEvent 2 1 setChannel 20 0
alias set90deg backlog setChannelFloat 20 0.2; turn_off_after_time

The following will explicitly call delay and reset after you set given position in the servo.

CodeFaux · Answer

>>21465242

The 'addChangeHandler' Channel20 != 0 'turn_off_after_time' trigger is not called when a transition from 0 to non-0 happens. I know it should, but it does not. I tested it. That's why I said it doesn't work.

You have provided an alias to set to 90 degrees. I do not want to change to 90 degrees. I need to turn off PWM, automatically, after ~2sec, any time PWM is turned on to any value. The angle is not known ahead. I don't always need 90 degrees. I need to turn off PWM after ~2sec, always. 'addChangeHandler' should provide this, but it does not work for me. Can we fix this?

p.kaczmarek2 · Answer

Can you provide more information how to replicate addChangeHandler not working?
I've tried to check addChangeHandler in self test but it passes both on my machine and on Github.

Test commit:
https://github.com/openshwprojects/OpenBK7231...mmit/8c01b0cf83aaa2f34d2498b25b163ac1c51ebe8e
Screenshot:

Unless the problem is in the float version?
It seems that's the case...
Well, for now, I can try to add a work around, but I am not sure if it will work good with fractional parts, I will try to look into it a bit later more. I will just most likely adjust change callbacks to work with floating points internally.

CodeFaux · Answer

Here is my autoexec.bat set with buttons for initial testing. I will remove buttons and control differently later. Code: text Expand Select all Copy to clipboard PWMFrequency 20 startDriver httpButtons setButtonEnabled 0 1 setButtonLabel 0 Close setButtonCommand 0 setChannelFloat 20 5 setButtonEnabled 1 1 setButtonLabel 1 Open setButtonCommand 1 setChannelFloat 20 1 setButtonEnabled 2 1 setButtonLabel 2 Release setButtonCommand 2 setChannelFloat 20 0 alias turn_off_after_time addRepeatingEvent 2 1 setChannel 20 0 addChangeHandler Channel20 != 0 turn_off_after_time I expect: Click any button. Servo moves. ~2sec later, servo turns off. I get: Click any button. Servo moves. Servo never turns off. Version: Built on Mar 2 2025 22:30:59 version 1.18.53 Device template; Code: text Expand Select all Copy to clipboard {   vendor: Tuya,   bDetailed: 0,   name: aaa,   model: aaa,   chip: BK7231N,   board: TODO,   flags: 0,   keywords: [     TODO,     TODO,     TODO   ],   pins: {     6: Btn;0,     7: IRRecv;0,     8: WifiLED;0,     9: PWM_ScriptOnly;20,     26: IRSend;0   },   command: ,   image:    wiki:  }

CodeFaux · Answer

Nevermind, I will find another solution. Thank you for your time.

p.kaczmarek2 · Answer

I haven't seen this message. Maybe you can give a repeating event with time delay instead? Or .. use Berry. We've added Berry script 10 days ago, maybe you can use that:

miegapele · Answer

Not mixing setChannel with setChannelFloat should work, like this:

alias turn_off_after_time addRepeatingEvent 2 1 setChannelFloat 20 0

The bug is that setChannel does not update float value properly and prevents event triggering

p.kaczmarek2 · Answer

Maybe we should really migrate to float channels, but will it be safe? I wouldn't want to break stuff

OpenBeken SG90 servo control configuration guidance, Home Assistant integration?

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