serial communication from nano to uno basic steps

stern · May 23, 2016, 2:21pm

hallo,
I have a basic problem using the rx/tx connectors of arduino boards nano and uno.

my project: because, after connecting a 2.8" display only less ports are free for input/output I want to connect a nano via rx/tx to the uno-board using this to show the values.

this seems to be easy but I have no success.

I´m searching a most simple code to implement to my other program parts.

and it should run over the rx/tx tx/rx pins ..... dont know why they are described so...and not useable?

has anyone a solution ? thank you!

Robin2 · May 23, 2016, 4:52pm

Post your code so we can see what you can see.

Use SoftwareSerial to communicate between the two devices so as to leave HardwareSerial free for debug messages.

Have a look at Serial Input Basics - the 3rd example will be most reliable.

...R

stern · May 23, 2016, 6:56pm

hmmm

I won´t show my codes...I know they are not korrekt.

I´m virtuoso in serial communication with basic-language... but not with C

but that seems not to be the problem.

there are any charakters appearing on the screen. but I dont know where these are received from.

the NANO works perfect and I get korrekt values on the serial monitor.
these values should appear on the UNO-display.

my questions: must tx/rx pins be aktivated? like this: pinMode(...., OUTPUT); ?

what date-format do the transmitted data have? o.k. they are digital... ? start/stop-bit?
how many data-bits? must I take my osci first?

and how must the UNO read them.... as a string? or single char-value.

I tried everything....no satisfying effect... always the same numbers...without sens. the whole ASCII- code-table...may be . it is possible that the nano doesn´t send on TX. but the values appear on the serial monitor as I discribed above... but I want to see them at the 2.8" display.

how can I get tft.println(values) ?

thank you trying to help me

ps

osci says: data are flowing from NANO. 1 start-bit 48 data-bit? 5 char and CR?

now I have an idee: may it be serial receiving is unable if usb is connected with the PC? fact is: USB doesn´t work if TxD is connected with the NANO ???????

Robin2 · May 24, 2016, 7:39am

stern:
I won´t show my codes...I know they are not korrekt.

That is silly. There would be no need to post code if it was correct.

Everyone on the Forum posts incorrect code - you will be among friends.

Without seeing your code it is impossible to make sense of your description.

...R

stern · May 24, 2016, 10:22am

no...it´s not silly.
I will send code, as soon as possible.
first I must do it by myself. I now know: the NANO is sending data without problems. further I can receive these data as CHAR.... but only one by one
I can´t find any example what a char is... is it to treat like a string? it seems do be restistant.

it will work if I exactly know how to create length of data( buffer-size) string-length or such as.....
and buffer must be cleared... there are always the same data in char...until reset....

to night I see more.
then if the first NUMERIC-value appears on my 2.8" screen... I send both codes (NANO and UNO) an you can correct it please.

Robin2 · May 24, 2016, 5:37pm

stern:
further I can receive these data as CHAR.... but only one by one
I can´t find any example what a char is... is it to treat like a string? it seems do be restistant.

If we can see your code it makes it much easier to understand your thinking and then to explain things.

Technically, a char is a signed 8 bit value, whereas a byte is an unsigned 8 bit value. A string is an array of chars terminated with a char having a value of 0.

However I won't be surprised to hear that is not answering the real question in your mind.

...R

stern · May 24, 2016, 8:27pm

this is the actually used code on the UNO with display:

// UNO
// IMPORTANT: Adafruit_TFTLCD LIBRARY MUST BE SPECIFICALLY
// CONFIGURED FOR EITHER THE TFT SHIELD OR THE BREAKOUT BOARD.
// SEE RELEVANT COMMENTS IN Adafruit_TFTLCD.h FOR SETUP.
//Technical support:goodtft@163.com
//  freie pins:  A3 A5    D10 11 12 13
#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_TFTLCD.h> // Hardware-specific library

// The control pins for the LCD can be assigned to any digital or
// analog pins...but we'll use the analog pins as this allows us to
// double up the pins with the touch screen (see the TFT paint example).
#define LCD_CS A3 // Chip Select goes to Analog 3
#define LCD_CD A2 // Command/Data goes to Analog 2
#define LCD_WR A1 // LCD Write goes to Analog 1
#define LCD_RD A0 // LCD Read goes to Analog 0

#define LCD_RESET A4 // Can alternately just connect to Arduino's reset pin




// Assign human-readable names to some common 16-bit color values:
#define	BLACK   0x0000
#define	BLUE    0x001F
#define	RED     0xF800
#define	GREEN   0x07E0
#define CYAN    0x07FF
#define MAGENTA 0xF81F
#define YELLOW  0xFFE0
#define WHITE   0xFFFF

Adafruit_TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);
// If using the shield, all control and data lines are fixed, and
// a simpler declaration can optionally be used:
// Adafruit_TFTLCD tft;

//char d1,d2,d3,d4;
char dat=0;


void setup(void) {
  Serial.begin(9600);
  
  Serial.println(F("TFT LCD test"));

#ifdef USE_ADAFRUIT_SHIELD_PINOUT
  Serial.println(F("Using Adafruit 2.4\" TFT Arduino Shield Pinout"));
#else
  Serial.println(F("Using Adafruit 2.4\" TFT Breakout Board Pinout"));
#endif

  Serial.print("TFT size is "); Serial.print(tft.width()); Serial.print("x"); Serial.println(tft.height());

  tft.reset();

  uint16_t identifier = tft.readID();
   if(identifier == 0x9325) {
    Serial.println(F("Found ILI9325 LCD driver"));
  } else if(identifier == 0x9328) {
    Serial.println(F("Found ILI9328 LCD driver"));
  } else if(identifier == 0x4535) {
    Serial.println(F("Found LGDP4535 LCD driver"));
  }else if(identifier == 0x7575) {
    Serial.println(F("Found HX8347G LCD driver"));
  } else if(identifier == 0x9341) {
    Serial.println(F("Found ILI9341 LCD driver"));
  } else if(identifier == 0x8357) {
    Serial.println(F("Found HX8357D LCD driver"));
  } else if(identifier==0x0101)
  {     
      identifier=0x9341;
       Serial.println(F("Found 0x9341 LCD driver"));
  }else {
    Serial.print(F("Unknown LCD driver chip: "));
    Serial.println(identifier, HEX);
    Serial.println(F("If using the Adafruit 2.8\" TFT Arduino shield, the line:"));
    Serial.println(F("  #define USE_ADAFRUIT_SHIELD_PINOUT"));
    Serial.println(F("should appear in the library header (Adafruit_TFT.h)."));
    Serial.println(F("If using the breakout board, it should NOT be #defined!"));
    Serial.println(F("Also if using the breakout, double-check that all wiring"));
    Serial.println(F("matches the tutorial."));
    identifier=0x9341;
   
  }

  tft.begin(identifier);

 
}

void loop(void) {

  if (Serial.available() > 0) {
       dat= Serial.read();
       

       
      
    }
   
//zeitformatierung 
  int time=millis()/1000;
int stime=time;  
int mtime=time/60;
int htime=time/3600;
int dtime=time/3600*24;
stime=stime-mtime*60;
mtime=mtime-htime*60;
htime=htime-dtime*24;7;


String sti = String(stime);
String mti = String(mtime);
String hti = String(htime);   
  
   tft.fillScreen(BLACK);
  unsigned long start = micros();
  
  uint16_t identifier = tft.readID();
  tft.setCursor(50,30);
  tft.setTextColor(BLUE); tft.setTextSize(1);
  tft.println("490323  20160516");
  tft.println("shield identfizierung:"),
  tft.println(identifier,HEX);
  tft.setTextColor(GREEN); tft.setTextSize(2);
   tft.println("anfang");
  tft.println(0);
  tft.print("zeit     "+ hti+":"+ mti+ ":"+sti);
  tft.println();
  tft.println();
  
  tft.setTextColor(BLUE);    tft.setTextSize(2);
   tft.println("uno  2.8inch  ");
  tft.println("daten seriell in");
  tft.setCursor(1,180);
  tft.println("volt    ");
   Serial.println(dat);
 
  
  tft.println(dat);
  
  tft.setTextColor(WHITE);    tft.setTextSize(2);
   tft.println("test  grundprogramm");
   tft.setTextColor(YELLOW);    tft.setTextSize(5);
   tft.println("");
   tft.setTextColor(RED);    tft.setTextSize(1);
   tft.println("ende");
  
  tft.println();
  
  delay(1000);delay(1000);delay(1000);delay(1000);delay(1000);
}
[Code/]

stern · May 24, 2016, 8:33pm

and this the code of the data sending NANO:

/*
 NANO 
 lademanager  solar-akku-wandler    lsaw   c20160505- wb49
               panel-spannung messen   analog  A2
               akku-spannung messen    analog  A3
               ssr (akku-hauptschalter) schalten D2 
               serielle schnittstelle öffnen
               werte verarbeiten
               bedingung für digitale ausgabe (if ..else)
               digitale ausgabe  als leuchtende LED
                
               
               ausgabe des anlog eingelesenen wertes durch den seriellen monitor
*/


// setup  des programmes

void setup() {
 #define adf 0.004882
 // initialize digital pin 13 and  3  as an output.
 pinMode(13, OUTPUT);
 pinMode(3,OUTPUT);
 pinMode(2,OUTPUT);   //  ssr ansteuern
 // öffnen der seriellen schnittstelle
 Serial.begin(9600);
 //ad-wandlung  faktor
 
 
 
 
}
 
// programm schleife

void loop() {
//float adf= 5.0/1024.0*10;

//up panelspannung
//ua akkuspannung 
float up = analogRead(A2);
float ua = analogRead(A3);

float U1 = up*adf;
float U2 = ua*adf*10;
//Serial.println(U1 ); 
Serial.print(U2 );




  
//  bedingungen für das schalten des ssr
//  z.b.  u1>u2    ssr einschalten   
// da nach einschalten des ssr u1=u2   
//  ausschalten des ssr wenn u1=u2< 36V
 
 if (U2 < 25.5 )  
 {
 digitalWrite(13, LOW);
 
 }
 else   if (U2 >41.2)
 {
 digitalWrite(13, HIGH);
 

 
 }
 
 
 
 
 delay(500);



               // wait for a second
}

[Code/]


I only want to show the measured values at the display   .........

stern · May 24, 2016, 8:41pm

value of experimental generated voltage for exampel 23.45 is shown asl

2
3
.
4
5

and so on.... it´s a loop only

how to get them in one row
and how are they always actual..... clear buffer ??

stern · May 24, 2016, 10:41pm

ahhhh

/*
void loop(void) {
   buf=""; 
  if (Serial.available()>0) {
     //  dat= Serial.read();
       
    for (int i=0;i<10;i++){
    buf += (char)Serial.read();
    }  
      
    }
 
[Code/]
a  step of success...

Robin2 · May 25, 2016, 7:02am

@stern, please modify your posts and use the code button </> so your code looks like this and is easy to copy to a text editor. See How to use the Forum Your code is too long to study quickly without copying to a text editor.

...R

stern · May 25, 2016, 1:46pm

robin......

why didn´t you write: insert with

/* ....  [Code/]

I´m  looking  1/4 h   for any "code-button"


programers  must be think:   everyone can , not  all,  but anything....  but not everyone thinks like a programer  ;)

Robin2 · May 25, 2016, 2:15pm

stern:
robin......

why didn´t you write:

I thought I did. My Reply #10 looks almost exactly the same as your #11

...R

stern · May 25, 2016, 2:29pm

I always used this quick-reply-window.....
there is no </>

a little bit knowledge now..... there is a reply-window and a </> -button.... yeah

Robin2 · May 25, 2016, 5:12pm

stern:
I always used this quick-reply-window.....
there is no </>

In my QuickReply window the </> is the first ICON on the left.
Maybe it is because I always edit in Source mode (the icon on the right). You can make this choice in your Profile. It makes posting links much easier.

...R

stern · May 26, 2016, 1:18am

now I have a rough but right working code. I hope you can see, what I mean.

/*
  NANO 
  lademanager  solar-akku-wandler    lsaw   c20160505- wb49
                panel-spannung messen   analog  A2
                akku-spannung messen    analog  A3
                ssr (akku-hauptschalter) schalten D2 
                serielle schnittstelle öffnen
                werte verarbeiten
                bedingung für digitale ausgabe (if ..else)
                digitale ausgabe  als leuchtende LED
                 
                
                ausgabe des anlog eingelesenen wertes durch den seriellen monitor
 */


// setup  des programmes

void setup() {
  #define adf 0.004882
  // initialize digital pin 13 and  3  as an output.
  pinMode(13, OUTPUT);
  pinMode(3,OUTPUT);
  pinMode(2,OUTPUT);   //  ssr ansteuern
  // öffnen der seriellen schnittstelle
  Serial.begin(9600);
  //ad-wandlung  faktor
  
  
  
  
}
  
// programm schleife

void loop() {
//float adf= 5.0/1024.0*10;

//up panelspannung
//ua akkuspannung 
float up = analogRead(A2);
float ua = analogRead(A3);
 
float U1 = up*adf;
float U2 = ua*adf*10;
//Serial.println(U1 ); 

Serial.print(U2 );
Serial.print("|");

 

   
 //  bedingungen für das schalten des ssr
 //  z.b.  u1>u2    ssr einschalten   
 // da nach einschalten des ssr u1=u2   
 //  ausschalten des ssr wenn u1=u2< 36V
  
  if (U2 < 25.5 )  
  {
  digitalWrite(13, LOW);
  
  }
  else   if (U2 >41.2)
  {
  digitalWrite(13, HIGH);
  

  
  }
  
  
  
  
  delay(500);

 
 
                // wait for a second
}

// UNO
// IMPORTANT: Adafruit_TFTLCD LIBRARY MUST BE SPECIFICALLY
// CONFIGURED FOR EITHER THE TFT SHIELD OR THE BREAKOUT BOARD.
// SEE RELEVANT COMMENTS IN Adafruit_TFTLCD.h FOR SETUP.
//Technical support:goodtft@163.com
//  freie pins:  A3 A5    D10 11 12 13
#include <Adafruit_GFX.h>    // Core graphics library
#include <Adafruit_TFTLCD.h> // Hardware-specific library

// The control pins for the LCD can be assigned to any digital or
// analog pins...but we'll use the analog pins as this allows us to
// double up the pins with the touch screen (see the TFT paint example).
#define LCD_CS A3 // Chip Select goes to Analog 3
#define LCD_CD A2 // Command/Data goes to Analog 2
#define LCD_WR A1 // LCD Write goes to Analog 1
#define LCD_RD A0 // LCD Read goes to Analog 0

#define LCD_RESET A4 // Can alternately just connect to Arduino's reset pin




// Assign human-readable names to some common 16-bit color values:
#define	BLACK   0x0000
#define	BLUE    0x001F
#define	RED     0xF800
#define	GREEN   0x07E0
#define CYAN    0x07FF
#define MAGENTA 0xF81F
#define YELLOW  0xFFE0
#define WHITE   0xFFFF

Adafruit_TFTLCD tft(LCD_CS, LCD_CD, LCD_WR, LCD_RD, LCD_RESET);
// If using the shield, all control and data lines are fixed, and
// a simpler declaration can optionally be used:
// Adafruit_TFTLCD tft;

//char d1,d2,d3,d4;
char dat[10];
String buf;
int lang;

void setup(void) {
  Serial.begin(9600);
  
  Serial.println(F("TFT LCD test"));

#ifdef USE_ADAFRUIT_SHIELD_PINOUT
  Serial.println(F("Using Adafruit 2.4\" TFT Arduino Shield Pinout"));
#else
  Serial.println(F("Using Adafruit 2.4\" TFT Breakout Board Pinout"));
#endif

  Serial.print("TFT size is "); Serial.print(tft.width()); Serial.print("x"); Serial.println(tft.height());

  tft.reset();

  uint16_t identifier = tft.readID();
   if(identifier == 0x9325) {
    Serial.println(F("Found ILI9325 LCD driver"));
  } else if(identifier == 0x9328) {
    Serial.println(F("Found ILI9328 LCD driver"));
  } else if(identifier == 0x4535) {
    Serial.println(F("Found LGDP4535 LCD driver"));
  }else if(identifier == 0x7575) {
    Serial.println(F("Found HX8347G LCD driver"));
  } else if(identifier == 0x9341) {
    Serial.println(F("Found ILI9341 LCD driver"));
  } else if(identifier == 0x8357) {
    Serial.println(F("Found HX8357D LCD driver"));
  } else if(identifier==0x0101)
  {     
      identifier=0x9341;
       Serial.println(F("Found 0x9341 LCD driver"));
  }else {
    Serial.print(F("Unknown LCD driver chip: "));
    Serial.println(identifier, HEX);
    Serial.println(F("If using the Adafruit 2.8\" TFT Arduino shield, the line:"));
    Serial.println(F("  #define USE_ADAFRUIT_SHIELD_PINOUT"));
    Serial.println(F("should appear in the library header (Adafruit_TFT.h)."));
    Serial.println(F("If using the breakout board, it should NOT be #defined!"));
    Serial.println(F("Also if using the breakout, double-check that all wiring"));
    Serial.println(F("matches the tutorial."));
    identifier=0x9341;
   
  }

  tft.begin(identifier);

 
}

void loop(void) {
   buf=""; 
  if (Serial.available()) {
    int len=Serial.available(); 
    
       
    for (int i=0;i<len;i++){
    buf += (char)Serial.read();
    }  
      
    }
 
//zeitformatierung 
  int time=millis()/1000;
int stime=time;  
int mtime=time/60;
int htime=time/3600;
int dtime=time/3600*24;
stime=stime-mtime*60;
mtime=mtime-htime*60;
htime=htime-dtime*24;


String sti = String(stime);
String mti = String(mtime);
String hti = String(htime);   
  
   tft.fillScreen(BLACK);
  unsigned long start = micros();
  
  uint16_t identifier = tft.readID();
  tft.setCursor(50,30);
  tft.setTextColor(BLUE); tft.setTextSize(1);
  tft.println("490323  20160516");
  tft.println("shield identfizierung:"),
  tft.println(identifier,HEX);
  tft.setTextColor(GREEN); tft.setTextSize(2);
   tft.println("anfang");
  tft.println(0);
  tft.print("zeit     "+ hti+":"+ mti+ ":"+sti);
  tft.println();
  tft.println();
  
  tft.setTextColor(BLUE);    tft.setTextSize(2);
   tft.println("uno  2.8inch  ");
  tft.println("daten seriell in");
  tft.setCursor(1,180);
  tft.println("volt    ");
  //controlle am seriellen monitor
   Serial.println(buf);
   lang=buf.length();
   Serial.println(lang);
  // vorläufige version den  messwert aus data zu separieren
  // bis mir was besseres einfällt oder ich einen vorschlag erhalte.   nach art basic: mid$
  //separatorposition bestimmen
    
   int pos=buf.indexOf('|');
  //für seriellen monitor 
   Serial.println(pos);

 //dies ist noch nicht so ganz das wahre..........aber erfüllt seinen zweck
  buf.toCharArray(dat,pos+1);
  Serial.println(dat);

  //anzeige auf TFT
  tft.setCursor(55,180);
  tft.print(dat);
  tft.println();
  
  tft.setTextColor(WHITE);    tft.setTextSize(2);
   tft.println("test  grundprogramm");
   tft.setTextColor(YELLOW);    tft.setTextSize(5);
   tft.println("");
   tft.setTextColor(RED);    tft.setTextSize(1);
   tft.println("ende");
  
  tft.println();
  
  delay(1000);delay(1000);delay(1000);delay(1000);delay(1000);
}

Robin2 · May 26, 2016, 6:17am

With this code

  if (Serial.available()) {
    int len=Serial.available();
   
       
    for (int i=0;i<len;i++){
        buf += (char)Serial.read();
    } 
     
  }

You have no idea whether 1 or 50 characters arrive.

Why not use the code in the link I gave you in Reply #1?

...R

stern · May 26, 2016, 10:14am

you mean this: ?

// Example 3 - Receive with start- and end-markers

const byte numChars = 32;
char receivedChars[numChars];

boolean newData = false;

void setup() {
    Serial.begin(9600);
    Serial.println("<Arduino is ready>");
}

void loop() {
    recvWithStartEndMarkers();
    showNewData();
}

void recvWithStartEndMarkers() {
    static boolean recvInProgress = false;
    static byte ndx = 0;
    char startMarker = '<';
    char endMarker = '>';
    char rc;
 
    while (Serial.available() > 0 && newData == false) {
        rc = Serial.read();

        if (recvInProgress == true) {
            if (rc != endMarker) {
                receivedChars[ndx] = rc;
                ndx++;
                if (ndx >= numChars) {
                    ndx = numChars - 1;
                }
            }
            else {
                receivedChars[ndx] = '\0'; // terminate the string
                recvInProgress = false;
                ndx = 0;
                newData = true;
            }
        }

        else if (rc == startMarker) {
            recvInProgress = true;
        }
    }
}

void showNewData() {
    if (newData == true) {
        Serial.print("This just in ... ");
        Serial.println(receivedChars);
        newData = false;
    }
}



To see how it works try sending "q

I first must understand this code. I´m a beginner

Topic		Replies	Views
Connecting PC to Arduino Uno and Uno to Nano Procedure Project Guidance	17	5719	May 5, 2021
Rx TX troubles... No serial communication. Programming Questions	17	1731	May 5, 2021
Serial communication over TX and RX pins doesn't work Nano RP2040 Connect	3	2780	April 14, 2022
Two arduino nano serial communication Programming Questions	21	1748	May 6, 2021
Arduino Nano vs Micro: TX/ RX pin functionality IDE 1.x	2	1067	May 5, 2021

serial communication from nano to uno basic steps

Related topics