Communication issue between an arduino uno (slave) and a nano (master)

Using Arduino Programming Questions
#1

Hello, and thanks in advance for your help… i’m having a problem with this setup.

I want to control a stepper attached to the master, with the parameters of speed and steps numbers given by the slave.

so, in theory, every time the master completes a cycle, it demands to the slave the speed and steps to do the next cycle.

BUT, i didnt finish the code because i’cant get the values from the slave.
when i request the only think i get is “-1”

i have created an array (called receipt) to hold the data, but testing out the master dont even get in the loop of
“while (Wire.available()) {…}”
so i write the folowing sentences just to force to read something from the uno… and when i print that on screen it shows -1…

as you can see on the slave code, it doenst matter how i command the “Wire.write()” neither sending a int (32) nor a byte (z)

please, i need some guidance here… im kinda beginner

Also i got them connected like:
UNO TX (pd1)-> NANO RX (pd0)
UNO RX (pd0)-> NANO TX (pd1)
UNO GND-> NANO GND

MASTER (NANO)

#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_PCD8544.h>
#include <AccelStepper.h>
#include <Wire.h>  

#define dirPin 6
#define stepPin 5
#define motorInterfaceType 1
AccelStepper stepper = AccelStepper(motorInterfaceType, stepPin, dirPin);

// SCK is LCD serial clock (SCLK) - this is pin 13 on Arduino Uno
// MOSI is LCD DIN - this is pin 11 on an Arduino Uno
// pin 9 - Data/Command select (D/C)
// pin 8 - LCD chip select (CS)
// pin 7 - LCD reset (RST)
Adafruit_PCD8544 display = Adafruit_PCD8544(9, 8, 7);

const int  endstopPin = 3;
const int  sleep = 4;

int cadencia = 10;
int volume = 500;
float velocidad;
float nPasos;

int i;

int receipt[] = {1,2,3};

void setup() {
    Serial.begin(9600);
    Wire.begin();
    
    display.begin();
    display.setContrast(50); 
    display.setRotation(2);
    display.clearDisplay();
   
    escribir (0,0,"VOLUMEN",1);
    escribir (0,10,"CADENCIA",1);

    pinMode(endstopPin, INPUT);
    pinMode(sleep, OUTPUT);

    stepper.setAcceleration(1000.0);
    stepper.setMaxSpeed(200);
    stepper.setSpeed(-200);

    i=0;
    display.fillRect( 20,  40,  30, 10, WHITE);
    while (i<3) {
        escribir (20+10*i,40,String(receipt[i]),1);
        i++;
    }
    
    //homming  
    activate();
    while(digitalRead(endstopPin)!=HIGH){
        stepper.runSpeed();
    }
    stepper.setCurrentPosition(0);
    deactivate();
}

void loop() {
      
    //escribe datos
    display.fillRect( 60,  0,  30, 10, WHITE);
    display.display();
    escribir (60,0,String(volume),1);
    escribir (60,10,String(cadencia),1);
    delay (20);

    //demanda parametros al esclavo
    display.fillRect( 20,  40,  30, 10, WHITE);
    i=0;
    Wire.requestFrom(5,3);
    while (Wire.available()) {
        receipt [i]= Wire.read();
        escribir (20+10*i,40,String(receipt[i]),1);
        i++;
    }
    
    i=0;
    while (i<3) {
        receipt [i]= Wire.read();
        escribir (20+10*i,40,String(receipt[i]),1);
        i++;
    }
    


     
    //calcula parametros
    int nPasos =  volume*0.8076;          // 200* VOL*10*pi()/i*pRosca*diam^2
    int velocidad = cadencia*nPasos/100;  // 2*CAD*(VOL*10*pi()/i*pRosca*diam^2)
    display.fillRect( 0,  20,  60, 10, WHITE);
    escribir (0,20,"np "+String(nPasos)+"  vel "+String(velocidad),1);

    // espera señal de arranque

    //ciclado
    stepper.setMaxSpeed(velocidad);
    
    activate();
    stepper.runToNewPosition(nPasos);
    deactivate();
    
    delay(1000);
    
    activate();
    stepper.runToNewPosition(0);
    deactivate();
    
    delay(1000);

    
}

//funciones utilizadas
void escribir(int16_t x, int16_t y, String texto, uint8_t s) {
  display.setCursor(x, y);
  display.setTextSize(s);
  display.setTextColor(BLACK);
  display.setTextWrap(false);
  display.print(texto);
  display.display();
}

void activate() {
    digitalWrite(sleep,HIGH);
}

void deactivate() {
    digitalWrite(sleep,LOW);
}

SLAVE (UNO)

#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ST7735.h>      // COLORES => ST7735_* (WHITE, BLACK, ETC)
#include <Arduino.h>
#include <Wire.h>  

// SCK is LCD serial clock (SCLK) - this is pin 13 on Arduino Uno
// MOSI is LCD DIN - this is pin 11 on an Arduino Uno
#define TFT_CS  2
#define TFT_RST 3
#define TFT_DC 4
Adafruit_ST7735 tft = Adafruit_ST7735(TFT_CS,  TFT_DC, TFT_RST);

const int  minusPin = 5;  
const int  plusPin = 6;  
const int  setPin = 7;

int cadencia;
int volume;
bool minus0;
bool minus1;
bool plus0;
bool plus1;
bool set0;
bool set1;

byte SlaveReceived = 0;

void setup() {
    Serial.begin(9600);
    Wire.begin(5);
//    Wire.onReceive(receiveEvent);          
    Wire.onRequest(requestEvent);  

    tft.initR(INITR_BLACKTAB);      
    tft.setRotation(1);             
    tft.fillScreen(ST7735_BLACK);   
    
    pinMode(plusPin, INPUT);
    pinMode(minusPin, INPUT);
    pinMode(setPin, INPUT);

    cadencia = 15;
    volume = 600;
    escribir (0,0,"VOLUMEN",2, ST7735_YELLOW);
    escribir (0,50,"CADENCIA",2, ST7735_YELLOW);
    escribir (35,20,String(volume),2, ST7735_WHITE);
    escribir (35,70,String(cadencia),2, ST7735_WHITE);
}

void loop() {
  delay(100);
    
    //deteccion de entrada a configuracion
    if(digitalRead(setPin)==HIGH){
        delay(50);
        while(digitalRead(setPin)!=LOW){}
        
        //deteccion de botones PARA VOLUMEN
        volume = buttons (volume, 35, 20, 1000, 500, 100);

        //deteccion de botones PARA CADENCIA
        cadencia = buttons (cadencia, 35, 70, 20, 12, 1);
    }
   
}

//funciones utilizadas
void escribir(int16_t x, int16_t y, String texto, uint8_t s, uint16_t color) {
    tft.setCursor(x, y);
    tft.setTextSize(s);
    tft.setTextColor(color);
    tft.setTextWrap(false);
    tft.print(texto);
}

int buttons (int variable, int X, int Y, int max, int min, int delta){
    plus0=0;
    minus0=0;
    tft.fillRect( X,  Y,  60, 20, ST7735_BLACK);
    escribir (X,Y,String(variable),2, ST7735_RED);
    while(digitalRead(setPin)!=HIGH){
        plus1 = plus0;
        plus0 = digitalRead(plusPin);
        delay(50);
        if (plus0 != plus1) { 
            if (plus0 == HIGH) { //se registra el cambio del boton delta, incrementando la cadencia y mostrandola en pantalla
                tft.fillRect( X,  Y,  60, 20, ST7735_BLACK);
                variable= variable + delta;
                if(variable > max) variable = max;
                escribir (X,Y,String(variable),2, ST7735_RED);
            }
        }
        
        minus1 = minus0;
        minus0 = digitalRead(minusPin);
        delay(50);
        if (minus0 != minus1) { 
            if (minus0 == HIGH) { //se registra el cambio del boton delta, incrementando la cadencia y mostrandola en pantalla
                tft.fillRect( X,  Y,  60, 20, ST7735_BLACK);
                variable= variable - delta;
                if(variable < min) variable = min;
                escribir (X,Y,String(variable),2, ST7735_RED);
            }
        }
    }
    tft.fillRect( X,  Y,  60, 20, ST7735_BLACK);
    escribir (X,Y,String(variable),2, ST7735_WHITE);
    delay(50);
    while(digitalRead(setPin)!=LOW){}
    return (variable);
}

void requestEvent(){
//  byte z = 35;
//  Wire.write(z);
  Wire.write(32);
}
#2

(deleted)

#3

yes, i'm trying to implement I2C protocols. So i use TX, RX and wire library... it isn't right?, why you say im using Serial? sorry i can't see the problem

#4

THANKS, I UNDERSTOOD... SO MUCH THANKS, I WAS DEALING WITH THAT NONSENSE ALLE THE MORNING! :) :)

#5

I2C is not serial. The UNO and the Nano use pins A4 and A5 for SDA and SCL. Connect those together with a pullup of 2K to 10K on each line then the wire.h functions should work.

As stated before, show your schematic.

#6

1. Make connection between NANO and UNO as per following diagram (Fig-1) using I2C Bus.

i2cNanoUno.png
i2cNanoUno.png929×328 25.4 KB

Figure-1:

2. Testing Sketch (untested) //Master send 0x23 to Slave and receives 0x65 from Slave
Master-NANO Code

#include<Wire.h>

void setup() 
{
  Serial.begin(9600);
  Wire.begin();
  //-----------
  Wire.beginTransmission(0x05); //checking the presence of Slave at adr: 5
  byte busStatus = Wire.endTransmission();
  if(busStatus != 0)
  {
    Serial.print("Slave is not found...!");
    while(1); //wait for ever
  }
  Serial.println("Slave found.");
  //---------------------------
  Wire.beginTransmission(0x05);
  Wire.write(0x23);    //dending 0x23 to Slave as test data
  Wire.endTransmission();
  //--------------------------
  Wire.requestFrom(5, 1);   //1-byte data requested from Slave
  byte x = Wire.read();
  Serial.print("Data received from Slave is: ");
  Serial.println(x, HEX);
}

void loop() 
{

}

Slave-UNO Code

#include<Wire.h>
volatile byte x;
volatile bool flag = false;

void setup()
{
  Serial.begin(9600);
  Wire.begin(0x05);
  Wire.onReceive(receiveEvent);
  Wire.onRequest(sendEvent);
}

void loop()
{
  if(flag == true)
  {
    Serial.print("Data Received from Master is: ");
    Serial.println(x, HEX);
    flag = false;
  }
}

void receiveEvent(int howMany)
{
  x = Wire.read();
  flag = true;
}

void sendEvent()
{
  Wire.write(0x65);
}

i2cNanoUno.png
i2cNanoUno.png929×328 25.4 KB

#7