Hi Jose,

I have not yet experimented with inter-board communication with UART link. However, I am wondering why you absolutely want to transfer data from your ATmega328 to the ESP32, when the ESP32 could also fulfil the functions of your ATmega328? You are adding complexity and an extra module that will consume power.

Well, obviously, I don’t know your circuit, so I guess you probably need to spread the load over 2 microcontrollers (maybe because of the number of pins?). I’m just wondering 🙂

Anyway, you can read the following article which details each pin of the ESP32:

ESP32 Pinout Reference: Which GPIO pins should you use?

You will see that the ESP32 has 3 UART interfaces. While browsing through the comments I saw that Sara advised to go and watch this video to know more about it:

Additional ESP32 Serial Channels in Arduino IDE (Quickie)

However, I unfortunately did not find any specific article on the issue on the RNT website.
(but maybe there are some … maybe I didn’t look hard enough?)

I hope this will help you see things more clearly.

Dear Stéphane, first of all thanks a lot for your fast answer, I was working in UART communications between systems since 1985, long time ago, and I feel confident doing that, it’s a good way to exchange information, if you have not lots of info to transfer, referring to change the Atmega, there are different applications for different chips, I think the Atmega it’s good enough to do the job, and have some advantages over any other system in this specific situation, by a lot of different reasons, yesterday night, after write this comment I found the video from Andreas Spiess, the one you’re recommending me, but anyway I still have a doubt, GPIO and GPIO3, both are part of UART0, then the question is are USB and UART0 the same connection?, are them sharing same signals?

As far as i know this will be a way to use the three UART outputs:
/* ESP32 3 UARTs */
HardwareSerial Serial1(1);
HardwareSerial Serial2(2); // Choose two free pins
#define SERIAL1_RXPIN 12
#define SERIAL1_TXPIN 13
void setup()
{
Serial.begin(115200); // This is serial 0
Serial1.begin(9600, SERIAL_8N1, SERIAL1_RXPIN, SERIAL1_TXPIN); // This is serial 1, definning pins as we need
Serial2.begin(4800); // pin 16=RX, pin 17=TX, and this is Serial 2 with default pins
}
void loop()
{
// Do something wonderful, preferably using UARTs once defined
}

Dear Jose,

Okay, I bow 🙂

Maybe the simplest way to find out is to plug an LED on these pins and see if it lights up during an upload, don’t you think?

I’m sorry… I’m still a beginner in the fields that you probably know better than me, but here’s an idea that comes to mind…

Assuming you wish to use the DoIt ESP32 DevKit v1 board, you can also take a look at this documentation. It seems to indicate that the USB port is linked to Serial0:

Our answers have crossed!
But thanks for this piece of code, I take note of it 🙂

Good tip to use leds to know if we have flow on USB, I think you’re not a beginner, you really have a deep knowledge, but it’s not possible to deeply know absolutelly everything, thanks again for the whole of your help

Ha ha,

That’s very kind of you to say that, but I assure you I’m a real novice in this field!

Anyway, it was my pleasure to give you a (good) tip 🙂

Many thanks for your words, I hope to disturb you again in a near future