Trying to implement serial data transmission using two digital pins other than rx and tx between arduino and esp32 - arduino

Question

I am developing a car robot for that I am using arduino and motor driving shield. I am trying to send commands from esp32 to arduino(as I am getting commands to esp32 from internet).
commands like forward, backward, right, left, autonomous, manual.
as rx and tx are used by motor driving shield, I decided to transfer data from esp32 to arduino through custom serial communication(by sending pulses for certain amount of durations)
arduino code:
void setup() {
Serial.begin(9600);
Serial.println("started");
pinMode(cmd_pin, INPUT);
pinMode(data_validator, OUTPUT);
digitalWrite(data_validator, HIGH);
}
String check(){
//String s = "";
int serial_data = digitalRead(cmd_pin);
if(serial_data==LOW){
delay(10);
digitalWrite(data_validator, LOW);
unsigned long high_dur = pulseIn(cmd_pin, HIGH);
unsigned long low_dur = pulseIn(cmd_pin, LOW);
Serial.println("HIGH ");
Serial.println(high_dur);
Serial.println("low ");
Serial.println(low_dur);
if(high_dur<=5000 && low_dur>24000){
automatic = false;
return "Forward";
}
else if(high_dur<=10000 && low_dur>19000){
automatic = false;
return "Backward";
}
else if(high_dur<=15000 && low_dur>14000){
automatic = false;
return "Turing right";
}
else if(high_dur<=20000 && low_dur>9000){
automatic = false;
return "Turing left";
}
else if(high_dur<=25000 && low_dur>4000){
automatic = true;
return "autonomous";
}
else if(high_dur<=30000 && low_dur>1900){
automatic = false;
return "manual";
}
digitalWrite(data_validator, HIGH);
}
}
void loop(){
command = check();
//ruuning command
Serial.println(command);
// if (command=="autonomous")
// auton();
// else if (command=="manual")
// moveStop();
// else if (command=="Turing left")
// turnLeft();
// else if (command=="Turing right")
// turnRight();
// else if (command=="Forward")
// moveForward();
// else if (command=="Backward")
// moveBackward();
// else{
// if (automatic)
// auton();
//}
}
information is transferred through cmd_pin,.
when low occurs in cmd_pin Arduino set data validator to low denotes the esp32 to send data
high_duration and low_duration are measure and decision is taken based on the duration.
esp32 code:
void manual(){
serial_busy = true;
digitalWrite(cmd_pin, LOW);
while (digitalRead(data_validator)!=LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(30);
digitalWrite(cmd_pin, LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(1);
digitalWrite(cmd_pin,LOW);
delay(2);
digitalWrite(cmd_pin,HIGH);
serial_busy = false;
delay(10);
}
void forward(){
serial_busy = true;
Serial.println("Forward");
digitalWrite(cmd_pin, LOW);
while (digitalRead(data_validator)!=LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(5);
digitalWrite(cmd_pin, LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(1);
digitalWrite(cmd_pin,LOW);
delay(25);
digitalWrite(cmd_pin,HIGH);
serial_busy = false;
delay(10);
}
void backward(){
serial_busy = true;
Serial.println("Backward");
digitalWrite(cmd_pin, LOW);
while (digitalRead(data_validator)!=LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(10);
digitalWrite(cmd_pin, LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(1);
digitalWrite(cmd_pin,LOW);
delay(20);
digitalWrite(cmd_pin,HIGH);
serial_busy = false;
delay(10);
}
void right(){
serial_busy = true;
Serial.println("Right");
digitalWrite(cmd_pin, LOW);
while (digitalRead(data_validator)!=LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(15);
digitalWrite(cmd_pin, LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(1);
digitalWrite(cmd_pin,LOW);
delay(15);
digitalWrite(cmd_pin,HIGH);
serial_busy = false;
delay(10);
}
void left(){
serial_busy = true;
Serial.println("Left");
digitalWrite(cmd_pin, LOW);
while (digitalRead(data_validator)!=LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(20);
digitalWrite(cmd_pin, LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(1);
digitalWrite(cmd_pin,LOW);
delay(10);
digitalWrite(cmd_pin,HIGH);
serial_busy = false;
delay(10);
}
void auton(){
serial_busy = true;
Serial.println("going autonomusly");
digitalWrite(cmd_pin, LOW);
while (digitalRead(data_validator)!=LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(25);
digitalWrite(cmd_pin, LOW);
delay(1);
digitalWrite(cmd_pin,HIGH);
delay(1);
digitalWrite(cmd_pin,LOW);
delay(5);
digitalWrite(cmd_pin,HIGH);
serial_busy = false;
delay(10);
}
void setup(){
Serial.begin(115200);
pinMode(cmd_pin, OUTPUT);
pinMode(data_validator, INPUT);
digitalWrite(cmd_pin, HIGH);
}
void loop(){
//call the functions left or right ..
}
I am calling the functions left,right,.... based on my websocket output(Not Included here)
where I was wrong, or is there any other methods available?
constrains: Pins available in arduino : 2,13, A3,A4 ,A5 (all other pins are used by other components)
I am expecting the best way to transfer data between arduino and esp32 loss-less transmission
using the availble pins only.

Answer 1

There is a software serial library available that you can use to enable serial communication over any GPIO pins.
Arduino Software Serial