Please any advice for connecting shield for my project ?

[rdpdo]

Hello everyone,

I have a project consisting of making an ADC main board with a raspeberry PI4B which will allow me to measure differential voltages from a MEMS sensor on remote micro-boards.

These boards are connected to my main ADC board with 4-wire AWG32 cables + shield. The wires transport differentials analog outputs from MEMS IC.

I wonder how to connect the shield on the side of the ADC card and on the side of my MEMS micro-cards.

Could you give me your opinion please?

Thank you !

[robertferanec]

If you are not sure, the simple answer is: provide different options, test them and for production use the best one.

For example on number of boards I placed footprints between shield and board GND and tried to use capacitors or ferrite beads or 0R connections. In most cases, direct connection was the best, but, there were situations where I wanted to use something else.

[rdpdo]

Ok thanks you,

Some advice to place direct connection to GND only in one side (https://forum.allaboutcircuits.com/t...ielding.78211/). Do you think it is a good idea ?

[qdrives]

For motors we always had the best results connecting the shield at both ends.

I see that you are showing that shield connected to a 5th pin (as JST connectors are plastic). You would be creating a pig-tail. That way, shielding does not really help at higher frequencies (> 10MHz).

[robertferanec]

I am not super expert for this, but one side vs, two sides may only be important if both devices are powered from power main. if one of them is battery powered or if one is powering the other one what the effect of not connecting the other side would be?

What you may want to consider is:
- do you want to connect them directly or using a capacitor? For example, when connecting directly and both devices are powered from different power mains, you will have DC currents flowing through the shield. This may cause problems.
- can the cable behave like an antenna? If you have a noisy ground and if you connect this noisy ground to your cable, cable can create a very good antenna for some frequencies.

I have done some videos on shielding and emc:
- https://www.youtube.com/watch?v=F9tB6JtG7oQ
- https://youtu.be/gHF5JyJF-N4