Help with Master and slave Arduino code

Projects Programming
1

So I am trying to use the TX of the master Arduino to talk to the RX of the Slave Arduino. I am wanting to have a master with 8 buttons and when a button is pressed it sends a string to the slave Arduino, and the slave Arduino reads the incoming to a string, and depending on the string it will send/type a keystroke. When I uploaded the code initially it didn't work but I added Serial1 and now they can communicate. The problem is when I plug in the slave Arduino to a pc and power on the master it just repeats keystrokes 12345678 all at once every second or so. So before I even get to touch a pin to the ground ie (button press) it is sending all keystrokes at once and touching pins 1-8 to the ground doesn't visibly do anything. In short, I want to press 1 button out of 8 on the Master and have the Slave do the one action out of 8 and then wait for another keypress to send another action. Any help would be amazing.

MASTER and Slave are ATmega32u4
TX of master plugged into RX of slave
Buttons connected to digital pins 2-9 on the master Arduino sharing common ground.

Master Code

  /*
*/

// This section Defines the serial string variables. 
char Str1[3] = "B1";
char Str2[3] = "B2";
char Str3[3] = "B3";
char Str4[3] = "B4";
char Str5[3] = "B5";
char Str6[3] = "B6";
char Str7[3] = "B7";
char Str8[3] = "B8";

const int buttonPin[] = {2, 3, 4, 5, 6, 7, 8, 9};
int pinCount = 8;
int buttonState[] = {0, 0, 0, 0,0 ,0 ,0 ,0}; 
int prevButtonState[] = {HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, HIGH, HIGH};
 
long lastDebounceTime[] = {0, 0, 0, 0, 0, 0, 0, 0};
long debounceDelay = 150;

void setup() {
  setPrescaler();
// This is required for the use of thisPin and defines what pin the buttons are.
  for (int thisPin = pinCount - 1; thisPin >= 0; thisPin--) {
    pinMode(buttonPin[thisPin], INPUT);
    digitalWrite(buttonPin[thisPin], HIGH);
  }
  
// This is important because it tells the serial to began transmitting on the TX pin.
  Serial.begin(9600);
  Serial1.begin(9600); 
  
}


// Output actions. This will send a string "B1-8" to be written in the serial.
int outputAction(int currentButton) {
    if (currentButton + 1 == 1) {
      Serial1.write(Str1,2);
      Serial.write(Str1,2);
      wait(5);
    }
    
    if (currentButton + 1 == 2) {
      Serial1.write(Str2,2);
      Serial.write(Str2,2);
      wait(5);
    }
    
    if (currentButton + 1 == 3) {
      Serial1.write(Str3,2);
      Serial.write(Str3,2);
      wait(5);
    }
    
    if (currentButton + 1 == 4) {
      Serial1.write(Str4,2);
      Serial.write(Str4,2);
      wait(5);
    }
    if (currentButton + 1 == 5) {
      Serial1.write(Str5,2);
      Serial.write(Str5,2);
      wait(5);
    }
   
    if (currentButton + 1 == 6) {
      Serial1.write(Str6,2);
      Serial.write(Str6,2);
      wait(5);
    }
    
    if (currentButton + 1 == 7) {
      Serial1.write(Str7,2);
      Serial.write(Str7,2);
      wait(5);
    }
    
    if (currentButton + 1 == 8) {
      Serial1.write(Str8,2);
      Serial.write(Str8,2);
      wait(5);
    }
        
        
}
     

void loop() { // Main Function - workflow is called within loop();
for (int thisPin = pinCount - 1; thisPin >= 0; thisPin--) {
    buttonState[thisPin] = digitalRead(buttonPin[thisPin]);

//This is the code to tell when a button is pressed do action x defined up above @~98
    if ((buttonState[thisPin] != prevButtonState[thisPin]) && (buttonState[thisPin] == HIGH)) {
      if ((millis() - lastDebounceTime[thisPin]) > debounceDelay) {
        outputAction(thisPin);
        lastDebounceTime[thisPin] = millis();
      }
    }

    prevButtonState[thisPin] = buttonState[thisPin];
  }
}


void bootLoop() {
  //      digitalWrite(RXLED, LOW);   // set the LED on
  TXLED0; //TX LED is not tied to a normally controlled pin
  delay(200);              // wait for a second
  TXLED1;
  delay(200);
  TXLED0; //TX LED is not tied to a normally controlled pin
  delay(200);              // wait for a second
  TXLED1;
  delay(800);
}


void wait(int cycles) {
  for (int i = 0; i < cycles; i++) {
    if (slowMode) {
      delay(250);
    }
  }
}



void Button() {

}


void setPrescaler() {
  // Disable interrupts.
  uint8_t oldSREG = SREG;
  cli();

  // Enable change.
  CLKPR = _BV(CLKPCE); // write the CLKPCE bit to one and all the other to zero

  // Change clock division.
  CLKPR = 0x0; // write the CLKPS0..3 bits while writing the CLKPE bit to zero

  // Recopy interrupt register.
  SREG = oldSREG;
}

//TODO:
#define in_developer_mode 0 // Set to 1 if device is in developer mode

Slave Code

  /*
*/

#include <Keyboard.h>

#define slowMode 1

// Special characters definition
#define KEY_LEFT_CTRL   0x80
#define KEY_LEFT_SHIFT  0x81
#define KEY_LEFT_ALT    0x82
#define KEY_RIGHT_CTRL  0x84
#define KEY_RIGHT_SHIFT 0x85
#define KEY_RIGHT_ALT   0x86
#define KEY_UP_ARROW    0xDA
#define KEY_DOWN_ARROW  0xD9
#define KEY_LEFT_ARROW  0xD8
#define KEY_RIGHT_ARROW 0xD7
#define KEY_BACKSPACE   0xB2
#define KEY_TAB         0xB3
#define KEY_ENTER       0xB0
#define KEY_ESC         0xB1
#define KEY_CAPS_LOCK   0xC1

// This section Defines the serial string variables. 
char IncommingButton[3];
char Str1[3] = "B1";
char Str2[3] = "B2";
char Str3[3] = "B3";
char Str4[3] = "B4";
char Str5[3] = "B5";
char Str6[3] = "B6";
char Str7[3] = "B7";
char Str8[3] = "B8";

void setup() {
  setPrescaler();
  Keyboard.begin();
  
// This is important because it tells the serial to began receiving on the RX pin. 
  Serial.begin(9600);
  Serial1.begin(9600); // I added this one because Arduino IDE was using regular Serial
}


void loop() { // Main Function - workflow is called within loop();

    Serial1.readBytes(IncommingButton,2);
    

    if (IncommingButton == Str1, 2) {
      Keyboard.print("1");
      Keyboard.releaseAll();
    }
    
    if (IncommingButton == Str2, 2) {
      Keyboard.print("2");
      Keyboard.releaseAll();
    }
    
    if (IncommingButton == Str3, 2) {
      Keyboard.print("3");
      Keyboard.releaseAll();
    }
    
    if (IncommingButton == Str4, 2) {
      Keyboard.print("4");
      Keyboard.releaseAll();
    }
    if (IncommingButton == Str5, 2) {
      Keyboard.print("5");
      Keyboard.releaseAll();
    }
   
    if (IncommingButton == Str6, 2) {
      Keyboard.print("6");
      Keyboard.releaseAll();
    }
    
    if (IncommingButton == Str7, 2) {
      Keyboard.print("7");
      Keyboard.releaseAll();
    }
    
    if (IncommingButton == Str8, 2) {
      Keyboard.print("8");
      Keyboard.releaseAll();
    }
}


void bootLoop() {
  //      digitalWrite(RXLED, LOW);   // set the LED on
  TXLED0; //TX LED is not tied to a normally controlled pin
  delay(200);              // wait for a second
  TXLED1;
  delay(200);
  TXLED0; //TX LED is not tied to a normally controlled pin
  delay(200);              // wait for a second
  TXLED1;
  delay(800);
}


void repeatKey(byte key, int num) {
  for (int i = 0; i < num; i++) {
    Keyboard.write(key);
    wait(1);
  }
}

void wait(int cycles) {
  for (int i = 0; i < cycles; i++) {
    if (slowMode) {
      delay(250);
    }
  }
}



void setPrescaler() {
  // Disable interrupts.
  uint8_t oldSREG = SREG;
  cli();

  // Enable change.
  CLKPR = _BV(CLKPCE); // write the CLKPCE bit to one and all the other to zero

  // Change clock division.
  CLKPR = 0x0; // write the CLKPS0..3 bits while writing the CLKPE bit to zero

  // Recopy interrupt register.
  SREG = oldSREG;
}
2

  1. when you do array == array you compare pointers, and they never going to match

  2. adding , 2 after comparison makes no sense, all it does is it makes whole if expression return true

Basically your ifs look like this to compiler

if (false, true)…

Pure nonsense

3

Hi @JohnnyKi11z

Take a look at how the two Arduino Nanos communicate with each other in this tutorial:

4

Ok well, that's very helpful. My intention with that was to say if the incoming button string is the same as Str1 then run code. Because the sent string is B1 and on the receive Arduino Str1 = "B1" I thought it would work. I only added the ,2 because I was trying to tell it the string is 2 characters long but I guess that's not needed based on your above comment? I am new to Arduino and just trying to make sense of everything.

5

I know roughly how it is supposed to work, I don't want to use TX on the slave Arduino because I plan to have 1 master and 20 slaves, and I'm not trying to complicate the setup by having 20 slaves talk back to the master. I was under the impression from tutorials I watched that if I connect TX from master to RX of slave that should be all that is needed for one-way communication right?

6

Or I guess the proper question should be. How can I compare a received string through the serial to a known string and if it received string matches the known string do action x?