SoftwareSerial TX problem

Official Hardware Nano Family Classic Nano
1

Hi!
I'm using Arduino nano with the library "SoftwareSerial.h" and I have a problem with the TX pin.
Problem is:
When I'm using pin no.11 as TX pin, no transmitting happening, only receiving. I discovered that when I comment on some part of code, TX on 11 then working normally.
Part of the code I comment on is no related to pin no. 11 and I'm not using pin no. 11 anywhere in code except in the constructor of SoftwareSerial.
Also discovered when I change the TX pin from pin no. 11 to pin no.12, everything is working fine - without commenting code.
Is it possible that is somehow related to the memory location issue or something like that?
I'm using now :
RAM: [==== ] 37.3% (used 763 bytes from 2048 bytes)
Flash: [=== ] 29.6% (used 9092 bytes from 30720 bytes)

2

Hi!

Do you realise we can see neither code, nor schematic?

3

Some code certainly can have a mysterious effect on pins, without the pins being explicitly defined in your sketch. Hardware SPI is an example which, incidentally, can affect exactly the pins you have been discussing.

4

I'm confused because when I comment on some random part of the code TX line again works.
And I'm not using any other library related to the physical pins of Arduino.

5

See reply #2

6

Here is part of the code that is related to that issue.

code
code1215×854 51.5 KB

When i comment those lines, it is working.

7

Here is part of my answer:

8

What is the value of RELAY_1 in that code snippet ? 11 by any chance ?

9

Pictures of code are not ideal. The how to get the most from this forum post has instructions on how to properly post code. Use the IDE autoformat tool (ctrl-t or Tools, Auto Format) to format code before posting in code tags.

10

No, it is pin no.5, and that function "send_SMS(number,message_to_send)" not contains digitalWrite or anything related to physical pins ,but contains thihg related to SoftwareSerial - example smsModem.print(message);

void send_SMS(String number, String message)
{
    wdt_reset(); //Reset watchdog timer

    if (setup_over)
    {
        String phone_numb = "AT+CMGS=\"" + number + "\""; //Phone number string format
        //smsModem.println(phone_numb);

        while (true)
        {

            if (smsModem.available() > 0)
            {
                String incomingResponce= smsModem.readString(); // Read  string from modem

                if (incomingResponce.indexOf("MODEM:STARTUP") != -1) // Modem send this message if restarted
                {
                    setup_over = false;
                    break;
                }

                if (incomingResponce.indexOf('>') != -1) // Waiting ">" from modem for sending message
                {
                    smsModem.print(message);    //Print message to modem
                    smsModem.println((char)26); // CTRL+Z (char for send message)
                    incomingResponce = "";
                    Serial.println("Sending message..."); //Debug
                    delay(5000);                          //pause for network to send sms
                    smsModem.println("AT+CMGD=1,4");      //Delete message from memory of modem
                    Serial.println("Message SENT!");      //Debug
                    delay(100);
                    break;
                }
                else if (incomingResponce.indexOf("ERROR") != -1) //Modem send this message if command is wrong
                {
                    break;
                }
            }
        }
    }
}
11

So, I found the solution! I literally changed the library from SoftwareSerial.h to NeoSWSerial.h and now all works fine! Seems like the SoftwareSerial library is not so good... following lines are ONLY lines that I changed in code:

//#include <SoftwareSerial.h>
#include <NeoSWSerial.h>

NeoSWSerial smsModem(RX_pin,TX_pin); //Rx pin,Tx pin
//SoftwareSerial smsModem(RX_pin,TX_pin); //Rx pin,Tx pin
12

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