Adding Watts to RMS example

[ncohen17]

Hi,

I wanted to know if it would be possible for you to add the Watts (Power) readings to the recently added Example 4 RMS voltage and current. so that it would be possible to read RMS values of voltage, current and power like in Example 1.

Best Regards
Netanel

[PaulZC]

Hi @ncohen17 ,

It will take us some time to do this. I will need to set up my ACS37800 test bed with AC source and load. And I do not have time to do that right now.

If you want to have a go at this yourself, you will need to replicate readRMS and adapt it so it reads ACS37800_REGISTER_VOLATILE_21 into a ACS37800_REGISTER_21_t struct and then extracts pactive and pimag. There is also papparent in ACS37800_REGISTER_VOLATILE_22.

If you get it working, please send us a Pull Request.

Best wishes,
Paul

[ncohen17]

Hi @PaulZC

Thanks for your reply.

I don't know nor have the experience to do it.

I would prefer to wait for you when you find the time.

When do you think you could have time to check it out and implement that feautre ?

Looking forward to hearing from you

Best Regards
Netanel

[ncohen17]

Hi @PaulZC ,

would it work if I make a simple equation in the existing example 4 code.

watts = volts x amps

Let me know your thoughts about this.

Looking forward to hearing from you

Best Regards
Netanel

[PaulZC]

Hi Netanel,

Calculating the V.A will give a good indication of the power drawn by the load, but it does not provide the full picture.

AC loads can be 'reactive' (inductive usually) and the current is out of phase with the voltage. To get the full picture, you need to know the Real, Reactive and Apparent Power:

https://en.wikipedia.org/wiki/Power_factor

The ACS37800 uses the terms Active, Imaginary and Apparent.

I am working on a lot of other projects at the moment. I will try and add this feature for you, but it will not be soon. Why not try and improve your coding skills and have a go yourself? ;-)

Best wishes,
Paul

[PaulZC]

Hi Netanel (@ncohen17 ),

I have added this in v1.0.5. Please update your library and give the new Example5 a try.

Best wishes,
Paul

[ncohen17]

Hi @PaulZC ,

I wanted to know if there is a way to read overall energy load consumption in kWh directly from the ACS37800 or would that need to be done using a separate calculation ?

Looking forward to hearing from you

Best Regards
Netanel

[PaulZC]

Hi Netanel (@ncohen17 ),

The ACS37800 has no built-in timing / clock / AC-cycle-counting functionality. It cannot measure energy use over time...

You could configure one of the DIO pins as "zero-crossing detection", connect it to an interrupt pin on your microcontroller, and use that to measure time (based on the AC frequency). But most microcontrollers have some form of built-in RTC which would be much easier to use.

Best wishes,
Paul