NeoThermic:
Hi,Had a bit of a search around but still a bit confused on this point.
I've got a project where the arduino is powered by USB from another device, which in turn takes its power from a 5v voltage regulator, connected to a battery pack.
My question is relating to grounding, and avoiding running too much current through the arduino's ground pins.
If i have my grounds linked (there is a wire connecting the arduino ground pin and the negative side of the battery PRE regulator) do I need to worry about too much current flowing through my arduino's ground pin
I have a few MOSFET controlled higher power LEDs etc which will take 100mA each. The intention is that the current will flow from the regulator, through these devices, through the MOSFET gate and down to ground of the battery, without ever passing through the arduino itself.
Will this happen? Does linking the ground to the negative achieve this? Thanks in advance!
Sounds like you are doing it correctly, but maybe redundantly so. The Arduino must have a common ground reference from the voltage source, and as you stated your Arduino is being powered via it's USB connector, and if that is a fact, then it will already have a ground reference established via the USB as that connector carries both +5vdc and a ground connection, as well as two data signal lines.
You external higher current drawing components (like your mosfet controlled LEDs) are best served if they have a dedicated ground reference wire to the voltage source, the battery in your case. That keeps higher ground return currents out of the arduino board and can help with noise suppression.
I see no advantage, only problems, with adding a diode in any of the ground leads as the prior poster suggested. Perhaps if he supplied a schematic drawing his idea might be better understood?
Lefty