I have multiple esp32s running to multiple SN74AHCT125N and plan to have 6 meter data lines in conduit to 2811 led strips. The leds are powered from 2 seperate power supplies and share a common ground with controllers and level shifters. The power cables to led strips are in a seperate conduit.
I’ve read having multiple data lines (6) running together would benefit from one or more ground lines running with them. My question is would these ground wires go from common ground to ground on the strips? Also, would they just run with the data lines as a bundle/loom or is there an optimum method such as wrapping around them? Thanks for any advice.
the GND return for the data signal should run from each strip in parallel with the data line, ideally twisted, back to the levelshifter for best noise performance.
Thanks for your reply. Since I am running power in a separate conduit, can I run a dedicated separate ground wire from the LED strip ground connection > twisted with data line > ground input on level shifter? The power wire is a heavy 20 amp rated pair, (LEDS may draw up to 15A collectively), will a lighter 18awg dedicated ground return still suffice? Thanks.
the idea behind the seperate GND for data is that the GND of the shifter and the GND of the LED strip are identical. depending on your layout this may become a bit more complex to avoid GND-curents in the data-GND due to GND shifts, this all depends on your layout and exact wiring but yes, in general a thin wire is sufficient.
Yes and in fact you should do this as it probably won’t work without a GND wire in each conduit. The wire gauge does not matter, 24AWG twisted pair is fine if that is what you have. As dedehai said, make sure the GND wire is connected directly to the GND on the shifter, closer is better.
OK. I have 6 data lines I need to run. I am planning on putting 3 in each of 2 shielded CAT6. Both CAT6 running in a single conduit. The CAT6 has double shielding. So from what I understand, the ground of each twisted pair connects to the common ground of the controller box and ground of strip. The shield needs to be grounded at only the controller end. Is it OK to connect the ground of twisted pair to common ground rather than directly to level shifter? It would just be a whole lot easier. Thanks
you can connect to common ground but keep connection to shifter GND short, like no more than 5cm or you can still get noise in and impedance mismatches. Shielded is not really needed but also wont hurt. Make sure to use the right data resistors to match that 100R diffpair.
Thank you. Can you please clarify, you say “keep connection to shifter GND short”. There is no shifter ground “out” as such, just an input terminal which is connected to a common ground terminal block. Can you please explain where I “connect to shifter ground”. Sorry but I’m just not understanding. Thanks.