Serial connection between ESP-32 and Arduino UNO

[saif_hossain]

I want to send data from my Arduino UNO to esp-32 via serial connection. I connected an Arduino UNO to esp-32 via tx-rx pins. It works fine when the delay() is greater than or equal to 999. When it is less than 999, the value is not transferred to esp-32. Is there any to reduce the delay time?

[Idahowalker]

Yes, there is a way to reduce the delay time.

[sterretje]

Show your code for both the ESP32 and the Uno.

Your topic has been moved to a more suitable location on the forum. Introductory Tutorials is for tutorials that e.g. you write, not for questions. Feel free to write a tutorial once you have solved your problem

[saif_hossain]

how can i reduce it?
can you please provide me any way?

[Idahowalker]

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If you are using a 9V battery like this.

Don't.

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Info about multi things

Demonstration code for several things at the same time

NOTE for newcomers. The demo is entirely contained in this Post and Reply #1. There is no need to read further unless you are interested. ...added 25Sep2014 There have been a few occasions recently where newcomers seemed to have difficulty applying the "blink without delay" and "state" concepts to a sketch that is intended to manage a number of concurrent actions. Its very time consuming to respond with suitable code examples - particularly as every case is a little different. I have prepared…

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I2C scanner

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How to Scan and Detect I2C Addresses

What did the I2C scanner report?

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Bread board power rail split

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Serial Input basics.

Serial Input Basics - updated

Updated Version Please note that this is a revised version of the advice in this earlier Thread which has become very long. As far as possible I have kept the code examples identical or simplifed them slightly. It should not be necessary to refer to the older Thread, but feel free to do so. Contents The following sections are in this Tutorial Introduction Serial data is slow by Arduino standards Example 1 - Receiving single characters Why code is organized into functions Exampl…

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[horace]

have a look at thread communication-between-esp32-cam-and-arduino-uno

[saif_hossain]

sure, here is my code for arduino uno:

void setup() {
  Serial.begin(115200);
}
void loop() {
  int val = analogRead(A1);
  Serial.println("LDR value: "+ String(val));
  delay(999);
}

here is my code for esp-32:

#define RXp2 16
#define TXp2 17
void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial2.begin(115200, SERIAL_8N1, RXp2, TXp2);
}
void loop() {
    Serial.println("Received value: ");
    Serial.println(Serial2.readString());
}

[horace]

think you need to wait for serial data to arrive, e.g.

void loop() {
if(Serial2.available()) {
    Serial.println("Received value: ");
    Serial.println(Serial2.readString());
}
}

[saif_hossain]

Same result, not showing any output when delay is less than 999

[b707]

It happened because the readString() method waits timeout of 1 second. Do not use it, read the data yourself char by char with read() method

or decrease the timeout by

Serial.setTimeout() - Arduino Reference

[saif_hossain]

yeah, this is working, thank you very much