Transfer data from ESP32 to Arduino Uno using UART

[TomGeorge]

@jolucas245

I just removed both resistors, I'll test again

No, just the one resistor I told you.

@TomGeorge

Try removing the resistor between ESP32 Tx and the UNO Rx and try connecting direct.

Between the ESP32 Tx PIN and the UNO RX PIN.

You do have
Tx ESP32 to Rx UNO
and
Rx ESP to Tx UNO type connections?
Tom..

[jolucas245]

Right, I left only the TX of the Esp32 and the RX of the UNO connected directly.

[GigaNerdTheReckoning]

@jolucas245

In this case, the ESP32 serial port would be 115200, correct? just change the serial.begin?

I've tried to modify my code from earlier to send from an ESP32 (Serial1) to an Arduino (software serial). You can use a baud rate at 9600 or 115200 etc., it doesn't matter (this is just the transmission speed), but you have to make sure that the baud rate is the same on the 2 serial ports that are communicating with each other.

[jolucas245]

@GigaNerdTheReckoning

I've tried to modify my code from earlier to send from an ESP32 (Serial1) to an Arduino (software serial). You can use a baud rate at 9600 or 115200 etc., it doesn't matter (this is just the transmission speed), but you have to make sure that the baud rate is the same on the 2 serial ports that are communicating with each other.

I think I understood

[camsysca]

@jolucas245

Right, I left only the TX of the Esp32 and the RX of the UNO connected directly.

And ground, I hope.

[david_2018]

Keep the baud rate at 9600 between the ESP32 and UNO, softwareserial is highly unreliable at the faster baud rates.

[GolamMostafa]

@jolucas245

it uses the ESP32 as an Arduino receiver, and I need it to be the other way around. Could you help me?

@jolucas245

Unfortunately not, Golam

You want ESP32 to work as Transmitter and Arduino UNO to work as Receiver in UART Network.

In this tested Tutorial, the ESP32 indeed does communicate with Arduino UNO.

1. Build the following setup between ESP32 and UNO using level shifter as ESP32 is a 3.3V Device and the UNO is a 5V Device.

Figure-1:

2. Upload the following sketch in ESP32.

void setup()
{
  Serial.begin(9600);
  Serial2.begin(9600, SERIAL_8N1, 16, 17); //RX2 = GPIO16, TX2 = 17
}

void loop()
{ 
  Serial2.println("Hello!");
  delay(1000);
}

3. Upload the following sketch in UNO.

#include<SoftwareSerial.h>
SoftwareSerial SUART(10, 11); //SRX = DPin-10, STX = 17

void setup()
{
  Serial.begin(9600);
  SUART.begin(9600);
}

void loop()
{
  while (SUART.available() != 0)
  {
    char ch = SUART.read();
    Serial.print(ch);
  }
}

4. Check that Serial Monitor of UNO shows the message "Hello!" at 1-sec interval.

[jolucas245]

Alright Golam, I'm going to buy a level shifter, which one do you recommend? Is there a way to do it without level shifter ?

[GolamMostafa]

@jolucas245

Alright Golam, I'm going to buy a level shifter,

Get this one:

You may try with the following untested setup (Fig-1) which may work.

Figure-1:

[GigaNerdTheReckoning]

See example: Using the BD-LLC for Serial, for hooking up the level shifter, which Golum posted, to UART.

I have edited post #30 to demo the sending/receiving of your 2 different commands. sending 0 will instruct the Arduino to lock, sending 1 will instruct Arduino to unlock.

Sender ESP32:

@GigaNerdTheReckoning

  delay(1000);

  Serial.print("0");
  Serial1.print("0"); //send 0 to lock

  delay(1000);

  Serial.print("1");
  Serial1.print("1"); //send 0 to unlock

Receiver Arduino:

@GigaNerdTheReckoning

void showNewData() {
  if (newData == true) {

    newData = false;

    switch (receivedChar) {
      case '0':  // receiving 0 will lock
        Serial.println("lock");
        break;
      case '1':  // receiving 0 will unlock
        Serial.println("unlock");
        break;
    }
  }
}

Yes, keep baud rate at 9600 when using software serial.

Also, if you needed 2-way communication from Arduino UNO to ESP32 and from ESP32 to Arduino UNO, then you cannot send data both ways at the same time, and you will need to program collision avoidance, as software serial cannot handle simultaneous 2 way communication. Some simple additional code can be added for the collision avoidance, however, to keep it simple, I would just switch to the primary Arduino's hardware serial port for this (pins 0 & pin 1) when you are finished prototyping with software Uart. This will require you to disconnect the RX and TX lines when you are uploading a sketch to Arduino.

[GolamMostafa]

@GigaNerdTheReckoning

Serial1.print("0"); //send 0 to lock

Any advantage of sending a null-ended character instead of sending a single character -- the '0'?

[GigaNerdTheReckoning]

Feel free to optimize the code, but my sketch should work fine for OP's basic requirements.

Reminder for OP to look up Serial Input Basics - updated for a very comprehensive tutorial on serial communication, which include some more advanced parsing techniques. Don't watch YouTube for this stuff, there are too many sketchy tutorials, especially concerning serial communication.

[rodolfomartelli]

Finally!!!!! I changed UNO voltaje regulator to 3v, it works, but pin 14 and 15 on the esp32 where the key !!!!!!!! with 16 and 17 doesnt work !!!!!!!!!
THANKS SO SO SO MUCH !!!!!!!!!!! Greetings from Argentina !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[creativelogy]

Hi giga, is it true that i really cannot do 2 way communication at the same time? is there anything i can do to be able to do it at the same time? I really need it to finish my college project. Thanks!