shelly plus addon analog input

[ChrisROL]

Hi,

is there a possibility to use the shelly plus addon analog input on gpio 3 with an ntc resistor?
As far as i understood , the input works with an sawtooth comperator and the signal on gpio3 should be simular to an pwm signal.
Maybe it can be done in berry, but i have not worked with berry till now.

Regards Chris

[ChrisROL]

Hi there,

has really nobody any idea how to make the "analog" input at a shelly plus addon useable?

[ChrisROL]

This is exactly why I'm asking about a PWM input for Tasmota. I don't know how Berry is implemented in Tasmota and whether interrupts are supported. I had solved most of my previous problems using GEMU scripting

[sfromis]

And I answered about PWM input. Not supported. Interrupts are only workable if you create a native driver in C++, along the lines of the existing driver supporting pulse counting via interrupts.

ESP32 also has a pulse counter feature (PCNT) for counting pulses, but AFAIK this is not used by Tasmota, and while I'm not sure of any details, a cursory look does not look like this is supporting duty cycle.

[barbudor]

@ChrisROL an NTC will not generate an PWM signal. You would need additional circuitry for that.
The 'add-on' input are not straight connected to an ESP GPIO so you can't use an analog input

So instead of making it more complicated than it is, use what is supported by the hardware and the software.
Otherwise it's that you choice of hardware (the Shelly) is not appropriate to your project

[sfromis]

@barbudor What is suggested by what I saw is that the plus addon indeed has an analog input, which is not connected to an analog pin on the ESP32. Instead the addon has additional circuitry generating a sawtooth pulse, as one side input to a comparator, thus generating a PWM signal with the duty cycle matching the analog voltage.

Cool idea, I suppose, but it is only workable if the software on the ESP32 is able to detect the duty cycle. Which should not be a "big problem", if someone decided to code a driver to handle that, maybe on top on the counter driver which can be used to determine frequency.

Yeah, Shelly does seem to like making things more complicated, instead of just providing simple gpio connections.....

[ChrisROL]

I think shelly goes this way, because there power supply for the ESP is not isolating the 3,3V from the 230V.
I guess the duty cycle measuring shoul be possible, the original shelly firmware does support it.
Unfortunately, with my very limited programming skills, I am unable to adapt the counter driver

[Jason2866]

The pragmatic way, replace the Shelly with an esp32 and use the adc ntc feature implemented in Tasmota.

[ChrisROL]

Sound very easy, but there is a reason why i choiced the shelly plus with addon.
In a very simular room with nearly the same conditions i did it with a LUANI HVIO Modul and a printed case.
But in this room the heater mat needs 230V/7A and the controller should be placed in a german flush-mounted box
If you know a device, better matching to my requirement than the shelly, please tell me. I'm not fixed to shelly but the NTC and the heating mat are not really changeable.

[sohail-bakhtiari]

Another - may be overkill - solution would be to simulate a DS18B20 using a micro-controller.
There are good comments and links here:
#17133

[ChrisROL]

Hi,
it's me again. Has somebody a suggestion for a different hardware for my floor heating?
I have a NTC for the floor temperature, a DHT22 for the room temperature (could be changed) and need a relais for 230V min. 7A .
Or is somebody able to do the programming of a additional driver? If necessary, i would also provide my hardware components.