What should I do with these ground signals?

Dennis Farquhar

Tom Also has good points

Tom LeMense

There are two considerations for if/how grounds should be linked: First: if the grounds must be at the same electric potential. This is generally true for circuits that share 'single-ended' signals; for example, the digital and analog inputs and outputs of an Arduino. When circuits share 'differential' signals, a common ground signal is often not necessary. So, to be sure, check with the electrical engineer that designed the circuit, to confirm if these grounds should be isolated or common. I agree with RAfzal; if the circuit designer wishes that the grounds are isolated, then different symbols and net-names should be used for each of the grounds. Second: for Signal Integrity and EMC/EMI reasons it is often important to consider how grounds are linked. For example, a circuit with high current flow in one area, and small logic current in another, might benefit from having a separate 'power ground' and 'logic ground'. This can prevent the transient currents flowing in the power section from disturbing the small signals in the logic section. However, these two grounds often need to be at the same electric potential, and so one solution is to connect them together only at a single point - so called 'star grounding'. There are many papers and books written on the subject of grounding, and they do not all necessarily agree.

Dennis Farquhar

I agree with RAfzal

Rebecca Afzal

If your grounds are isolated from each other then you should use differently named GND symbols in you schematic to denote this. Having the GNDs properly labeled will help in the future if you re-use the design or add to it.

Dennis Farquhar

Don`t think it will do harm to leave them or to link them up.