Wattcher help

[hobbes487]

I am working on the Wattcher project and have a couple questions. I have the hardware all built and it is working as best as i can tell. My question is about how to convert the incoming data into volts and current. I am writing my own program in C# so I'm not just copying your code.

1. Converting ADC0 to voltage:
In your loop to convert all the samples to voltage you have this equation: voltagedata[i] = (voltagedata[i] * MAINSVPP) / vpp
What should the value of MAINSVPP be? I figured it should be 340 in order to get a range of +-170

2. Converting ADC4 to current:
In your loop to convert the samples to current you have this equation: ampdata[i] /= CURRENTNORM
What should the value of CURRENTNORM be? I have no idea.

Any help would be awesome. great tutorial btw!

[adafruit]

theyre constants defined in the .py
look at the top of the code?

[hobbes487]

Thanks. I didn't see that until I looked at the full code. It wasn't in the snippets in the tutorial. How were these constants derived? I have been using the same constants as you and my measurements seem to be off. Would these constants need to be calculated on an individual basis?

[adafruit]

they were 'calibrated'/'guesstimated'
they may be off