Communication between RS485 module and esp8266

Using Arduino Project Guidance
1

Hello
I want to connect an RS485 module to an esp8266 and read the data coming from the RS485 module and display it on a 16 x 2 LCD. I connected the RX module pin 485 to the TX of the esp8266 and the TX pin of the 485 module to the RX of the esp8266. I also fed 5 volts to the 485 module. Are the connections correct? And what code should I write for the esp8266 module that can read the data and display it on the lcd?

800px-Item-D1_mini_Esp8266-wemos-d1-mini-pinout
800px-Item-D1_mini_Esp8266-wemos-d1-mini-pinout1896×528 84.9 KB

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3

D1 mini (with name upgrade to LOLIN D1 mini): https://www.wemos.cc/en/latest/d1/d1_mini.html with schematic.

The RS-485 module seems to work at 3.3V and 5V, according to websites here, here and here.
This website has a schematic:

afbeelding
afbeelding1241×543 24.1 KB

The RX and TX on the D1 mini are used by the serial-usb chip to upload a sketch, or do you upload a sketch via Wifi ? I think the RX and TX can not be used for something else.

The pins of the ESP8266 are more-or-less 5V tolerant. It might be possible to run the RS-485 module on 5V.

The ESP32 has a extra Serial2 that works, but the ESP32 is not 5V tolerant. The RS-485 module should be powered with 3.3V.

4

Thanks for your help
What about MAX3485? I think it works with 3.3 volts. Can MAX3485 be serially connected to a base other than RX and TX? Thanks if you have a code about ESP8266 serial connection with me.

5

Is there a library for RS-485 ?
The Arduino has a official RS-485 shield: Arduino MKR 485 Shield — Arduino Official Store
Can you read the Docs and the Quickstart Guide, to see if the Arduino RS-485 library is compatible with other hardware ?

Are you talking about the bare MAX3485 chip or a module with that chip.
The module that you have now, has a circuit with protection for voltage spikes.

The ESP8266 can run SoftwareSerial to create a serial port on any pins. I heard that it is not as bad as the SoftwareSerial on a Arduino Uno.

7

Thank you very much for your help
I had another question that using the SoftwareSerial library I want to display the read value on a 16 x 2 LCD. This is my code. I also defined the LCD. How can I display the Read parameter on the LCD?

#include <SoftwareSerial.h>
#include <Wire.h> 
#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27, 16, 2);
SoftwareSerial mySerial(6, 7); // RX, TX

void setup()
{
   lcd.begin();

  // Turn on the blacklight and print a message.
  lcd.backlight();
  
  // Open serial communications and wait for port to open:
  Serial.begin(115200);
 
  
  while (!Serial) {
    ; // wait for serial port to connect. Needed for Native USB only
  }

  Serial.println("Goodnight moon!");

  // set the data rate for the SoftwareSerial port
  mySerial.begin(38400);
  mySerial.println("Hello, world?");
}

void loop() // run over and over
{
  if (mySerial.available())
    Serial.write(mySerial.read());
  if (Serial.available())
    mySerial.write(Serial.read());
}
8

You could make a test-sketch and print variables and text on the display.

9

Your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project :wink: See About the Installation & Troubleshooting category.

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