ESP32 long data wire, any issues with this wiring?

Questions
1

My first project, do you see any issues?

  • 1s led ~ 15m from controller.
  • to run less wire- using 24v->5v converter to power 2nd RS485
  • Do I have to interconnect grounds on RS485s?

esp32
esp321920×1121 124 KB

2

Generally you should be OK with this approach.
Just a few details:

  1. You can power both RS485 boards and the ESP32 from a single 24->5V converter.
    The RS485 boards need very little power and the TX board (ESP end) can run at 5V as it has 3.3V compatible inputs. That will also give you a common ground between the RS485 boards.
    A small 4-wire (22/4, or 24/4) wire works well. You can even use 2 of the 4 pairs in a Cat5E cable.

  2. Make sure the GPIO from the ESP connects to the TXD pin on the RS485 Transmit board and the RXD pin on the Receive board connects to the LEDs.

  3. Solder the jumper near the R0 resistor to enable the 120R0 termination resistor on the Receive board.

  4. Watch out for issues with the GPIO pin you use. The Transmit board may pull that pin Hi, which can cause boot issues for the ESP depending on the pin you use.

3

Thank you @divsys

  1. the idea is to use less wires, I thinking to run single cable with 4 wires (pos/neg + data), then 24->5v for RS485. Or 3 wires with single QuinLED signal booster.

Or I do need common ground between RS485 and ESP32?

2, 3 are covered, 4 noted

Still waiting for components, studying theory for now :slight_smile:

4

Bare minimum would be 2 wires for data (the A/B lines).
Power needs common ground for all devices on the power supply side.
You can get away with no A/B ground although I often just tie it to the Vcc ground on each RS485.

A single cable (power and data) run is a nice idea for many installs. But if you realize your power and data requirements need different wiring types (and wiring rules) altogether, you’ll find your installs are more reliable and easier to troubleshoot.

Data wires are much smaller and don’t need to follow the power path (it’s often better if they don’t)

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5

Make sure, that the first RS485 chip works well with 3,3V level. It exist much, much derivats, but not all will run stable with 3,3V level. Often is the name from 3,3V versions xx3485

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6

Almost all parts are here, will report back once I get everything