Simple Multiple RX/TX SoftwareSerial?

Question

In this project I will be using multiple ESP8266 WiFi modules (4) connected by software serial to an Arduino Leonardo Micro (1 UART). I plan to rotate between all 4 (starting with 2): Open port, write, read response, close port, move on....

This is a very barebones version of my code to address this one issue. Works flawlessly with a single (always open) connection, but it does not work when I close Ser1 (even if I don't start Ser2!!!) Is the xxxx.end(); command broken or something? Or am I doing something wrong? :/

Note: This code sends "AT" to the module, it responds with "OK"

When adding Ser2, LED flashes on Arduino periodically indicating it is writing to serial monitor, but nothing appears...

Code:

#include <SoftwareSerial.h>
SoftwareSerial Ser1(10, 8);
SoftwareSerial Ser2(16, 7);
SoftwareSerial Ser3(14, 4);
SoftwareSerial Ser4(15, 2);
//Set up (RX, TX) pins^
void setup() {
 pinMode(10, INPUT);
 pinMode(16, INPUT);
 pinMode(14, INPUT);
 pinMode(15, INPUT);
 pinMode(8, OUTPUT);
 pinMode(7, OUTPUT);
 pinMode(4, OUTPUT);
 pinMode(2, OUTPUT);
 Serial.begin(9600);
 //Set up Serial Monitor on host computer
}
void loop()
{
 delay(1000);
 Ser1.begin(9600); // open Ser1
 Ser1.write( 'A' );
 Ser1.write( 'T' );
 Ser1.write( '\r' );
 Ser1.write( '\n' ); // sends the line: "AT" with appropriate format
 Ser1.listen(); // make sure it's listening
 while ((Ser1.available() > 0)) { //Read entire string
 Serial.write(Ser1.read()); //Dump it to serial monitor
 }
 //Should Respond with "OK"
 Ser1.end(); //close Ser1 port
 //This breaks the code for some reason....
 Serial.println(); // Extra line in Serial Monitor for neatness
 Ser2.begin(9600); // open Ser2
 Ser2.write( 'A' );
 Ser2.write( 'T' );
 Ser2.write( '\r' );
 Ser2.write( '\n' );
 Ser2.listen();
 while ((Ser2.available() > 0)) {
 Serial.write(Ser2.read());
 }
 Ser2.end();
}

• Ignacio Vazquez-Abrams: Why are you beginning and ending the object each time instead of just beginning once?
• WaffleFPV: @Ignacio, Software serial is only capable of one connection at a time, so it must be closed before I switch to a different port. Problem is my attempt to close it breaks the code. :(
• Ignacio Vazquez-Abrams: No, it is capable of only receiving on one connection at a time.
• WaffleFPV: @IgnacioVazquez-Abrams Do you suggest beginning them all in setup? Then how can I switch the receiving from port to port?
• Ignacio Vazquez-Abrams: Exactly how you already are.

Answer 1

As Ignacio mentions, you should not be stopping and starting the serial ports. Instead just switch between them with .listen():

Enables the selected software serial port to listen. Only one software serial port can listen at a time; data that arrives for other ports will be discarded. Any data already received is discarded during the call to listen() (unless the given instance is already listening).

SoftwareSerial::listen() Manual Page

So your code would be written as:

#include <SoftwareSerial.h>
SoftwareSerial Ser1(10, 8);
SoftwareSerial Ser2(16, 7);
SoftwareSerial Ser3(14, 4);
SoftwareSerial Ser4(15, 2);
//Set up (RX, TX) pins^
void setup() {
 Serial.begin(9600);
 Ser1.begin(9600); // open Ser1
 Ser2.begin(9600); // open Ser2 
}
void loop()
{
 delay(1000);
 Ser1.listen(); // Select Ser1 for receiving
 Ser1.print(F("AT\r\n")); 
 delay(1000); // Give it time to send a response or you'll get nothing!
 while ((Ser1.available() > 0)) { //Read entire string
 Serial.write(Ser1.read()); //Dump it to serial monitor
 }
 //Should Respond with "OK"
 Serial.println(); // Extra line in Serial Monitor for neatness
 Ser2.listen(); // Select Ser2 for receiving
 Ser2.print(F("AT\r\n"));
 delay(1000); // Give it time to send a response or you'll get nothing!
 while ((Ser2.available() > 0)) {
 Serial.write(Ser2.read());
 } 
}

• WaffleFPV: I really appreciate how you fixed my problem AND optimised my code at the same time!! I think the main issue was not waiting for a response (I tried your fix lol). Amazing work!!