Hi i am trying to comunicate two arduinos using Serial pins. I can see the bytes im sending when I reset the arduino, but sudenly the message received is always the same has nothing to do with the bytes I am sending. The conections are just rx on arduino 1 to tx on arduino 2, and tx arduino 1 to rx on arduino 2, and a cable to ground of both. This is the code for the sender: const byte nitro[] = {0x01,0x03, 0x00, 0x1e, 0x00, 0x01, 0xb5, 0xcc}; void setup() { Serial.begin(9600); Serial.println("serial has started"); delay(3000); } void loop() { Serial.println("values ti be written : "); for(int i=0; i 0){ Serial.readBytes(message,8); } if(message[0]==start[0]){ Serial.println("NUEVO MENSAJE:"); for(int i=0;i<sizeof(message);i++){ Serial.println(message[i],HEX); } } else{ Serial.println("No se enconntro mensaje"); for(int i=0;i<sizeof(message);i++){ Serial.print(message[i],HEX); message[i]=0; } Serial.println(""); } delay(1000); } And this is the message that Im receiving: 616C756573207476

@arturovelasquez It was difficult for me to reproduce the fault of your sketch of post #1 with UART connection between two Arduinos. It is not recommended to use the UART Port for data exchange as these ports remain engaged with PC/IDE/SM. I have connected UNO and NANO using Software UART (SUART) Port as per Fig-1 and then have uploaded your sketches (with slight modifications) to receive message from Sender correctly. [uartUnoNano-1] Figure-1: Sender Sketch: #include SoftwareSerial SUART(2, 3); //SRX = 2, STX = 3 const byte nitro[] = {0x01, 0x03, 0x00, 0x1e, 0x00, 0x01, 0xb5, 0xcc}; void setup() { Serial.begin(9600); SUART.begin(9600); Serial.println("serial has started"); delay(3000); } void loop() { Serial.println("values ti be written : "); for (int i = 0; i SoftwareSerial SUART(2, 3); //SRX = 2, STX = 3 byte message[8]; byte start[4] = {0x01, 0x03, 0x00, 0x1e}; void setup() { Serial.begin(9600); SUART.begin(9600); } void loop() { if (SUART.available() > 0) { SUART.readBytes(message, 8); if (message[0] == start[0]) { Serial.println("NUEVO MENSAJE:"); for (int i = 0; i < sizeof(message); i++) { Serial.print(message[i], HEX); } Serial.println(); } else { Serial.println("No se enconntro mensaje"); } } } Receiver Output: NUEVO MENSAJE: 1301E01B5CC

If you want ASCII, look up the difference between “types” byte and char.

Did you want ? for (int i = 0; i < sizeof(nitro); i++) { //Serial.print(nitro[i],HEX); Serial.write(nitro[i]); }

Isn’t the serial on UNO is the same serial you connect to the monitor?

That worked perfectly. I still don't understand why it dosent work well with pins o and 1. I thought those were the ones desingned for this type of transmission. The project I am trying to build includes a NPK sensor that needs conversion from RS485 to TTL. I thought that connecting the conversion circuit to the UNO's tx and rx pins was the correct thing to do, but since I could not get any signal I simplified to just verify I could read and writte correctly using serial comunication. For future reference: should I avoid using pins 0 and 1 for comunication?

[image] arturovelasquez: I still don't understand why it dosent work well with pins o and 1. Hope that the following diagram (Fig-1) will help to visualize the stuff that are connected with Hardware UART Port of the ATmega328P MCU of the UNO Board. [uart-1x] Figure-1: [image] arturovelasquez: For future reference: should I avoid using pins 0 and 1 for communication? If you are making UNO-based project, then leave the UART Port for down loading/debugging the sketches.

Serial between two arduino UNO

Projects Programming

groundFungus August 9, 2022, 11:33pm 3

The serial input basics tutorial may be of interest.

Topic		Replies	Views
Serial communication Programming	6	563	August 13, 2024
Communication between 2 arduinos UNO, UART Programming	8	916	June 18, 2021
Serielle Kommunikation zwischen 2 Arduino Deutsch	25	1038	February 26, 2025
Communication between two arduino UNO via Tx and Rx Programming	9	17235	July 24, 2023
Serialle Komunikation Rx/Tx Deutsch	15	574	November 6, 2025

Serial between two arduino UNO

Related topics