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Current transformer connection to Nucleo U545REQ

reedomneck
Associate III

Hello,

I've configured my ADC channels in differential mode and I'm able to do some basic test by connecting variable supply to my ADC pins. The results are coming properly. Here I'm connecting directly to my Nucleo545REQ board.

 

Now when I connect CT(Current transformer) lines with 100watt load to my Nucleo board ADC I don't see anything. Values are in the range of floating.

Can someone help me if I need to do anything in firmware or do I need to have any change in hardware.

3 REPLIES 3
Andrew Neil
Super User

Welcome to the forum

Please see How to write your question to maximize your chances to find a solution for best results

Please show a schematic of how you are connecting the current transformer to the board.

If you probe with an oscilloscope on the STM32 pins, do you see valid signals at the ADC inputs?

 

Please also show your code - see How to insert source code 

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.

I'm reframing my query with additional details.

I'm using  NUCLEO-545REQ board for my project and I've created sample project in which I've enabled ADC in differential mode.

On NUCLEO-545REQ kit in CN8 connector A4 & A5(These are the pairs) are the differential ADC inputs where I'm directly connecting CT pins.

When I connect CT to these pins I don't see any results. Do I need to have anything here.
I verified ADC reading by connecting variable supply and looks fine.

It's far more effective to provide a schematic than to try to describe an electronics circuit in words!

 

Again, if you probe with an oscilloscope on the STM32 pins, do you see valid signals at the ADC inputs?

 

PS:

A current transformer gives a current output, whereas the STM32's ADC measures a voltage input - so you need to provide a load on the transformer.

https://www.electronics-tutorials.ws/transformer/current-transformer.html

https://circuitdigest.com/electronic-circuits/ac-current-measurement-circuit-using-current-transformer-and-arduino

A complex system that works is invariably found to have evolved from a simple system that worked.
A complex system designed from scratch never works and cannot be patched up to make it work.