Chars, strings and oled help please

qwilpen · April 29, 2022, 2:44pm

Hi 1st post asking for help, been trying to set up a nano, and a 128 x 64 oled for use on my model rail set up, i want the display to act as an arrival / departures board generating random times and destinations.

I can get it running using fixed times & destinations but am having issues with the random part, my current sketch is below.

any help would be greatly appreciated.

Steve


#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SH110X.h>

/* Uncomment the initialize the I2C address , uncomment only one, If you get a totally blank screen try the other*/
#define i2c_Address 0x3c //initialize with the I2C addr 0x3C Typically eBay OLED's
//#define i2c_Address 0x3d //initialize with the I2C addr 0x3D Typically Adafruit OLED's

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET -1   //   QT-PY / XIAO
Adafruit_SH1106G display = Adafruit_SH1106G(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);


char *myString[]={"London","Birmingham","Manchester","Munich","Berlin","Hamburg","Paris","Madrid","Rome","Amsterdam","Brussells",};
char *yoString[]={"10:15","10:20","10:25","10:30","11:15","11:25","11:35",};


void setup()   {

  Serial.begin(9600);
  delay(250); // wait for the OLED to power up
  display.begin(i2c_Address, true); // Address 0x3C default

  display.display();
  delay(2000);
  display.clearDisplay();
}
  
void loop()
{

  display.setTextSize(1.5);
  display.setTextColor(SH110X_WHITE);
  display.setCursor(0, 0);
  display.println("       ARRIVALS");
  display.setTextSize(1);
  display.println("10:20 Stutgartd");
  display.println("10:43 London");
  display.println("10:50 Hamburg");
  display.println("11:02 Paris");
  display.println("11:13 Rome");
  display.print("11:26"); display.println(" Berlin");
  display.display();
  delay(2000);
  display.clearDisplay();


  // text display tests
//  display.setTextSize(1.5);
//  display.setTextColor(SH110X_WHITE);
//  display.setCursor(0, 0);
//  display.println("       DEPARTURES");
//  display.setTextSize(1);
//  display.println("12:20 2Stutgartd");
//  display.println("12:43 2London");
//  display.println("12:50 2Hamburg");
//  display.println("13:02 2Paris");
//  display.println("13:13 2Rome");
//  display.print("13:26"); display.println(" 2Berlin");
//  display.display();
//  delay(2000);
//  display.clearDisplay();

  display.setTextSize(1.5);
  display.setTextColor(SH110X_WHITE);
  display.setCursor(0, 0);
  display.println("       DEPARTURES");
  display.setTextSize(1);


 
  for (int i = 0; i < 9; i++) {
  
   display.println(yoString[i+1])+(myString[i+1]);
   display.println(yoString[i+2]);(myString[i]);   
   display.println(yoString[i+3]);(myString[i]);
   display.println(yoString[i+4]);(myString[i]);     
   display.println(yoString[i+5]);(myString[i]);   
   display.println(yoString[i+6]);(myString[i]);
   display.println(yoString[i+7]);(myString[i]);  
  display.display();
  delay(2000);
  display.clearDisplay();

 }
 }

anon73444976 · April 29, 2022, 2:49pm

Not sure what is going on there, but those array indices are out of bounds.

jfjlaros · April 29, 2022, 2:50pm

Perhaps you want to use String instead of char* and do something like this?

   display.println(yoString[i+1] + myString[i+1]);

jremington · April 29, 2022, 2:52pm

"+" does not work with C-strings (zero terminated character arrays).

To concatenate C-strings, use strcat(), or better, strncat().

https://www.cplusplus.com/reference/string/string/

jfjlaros · April 29, 2022, 2:57pm

Didn't check the types, my mistake.

qwilpen · April 29, 2022, 2:59pm

qwilpen:

 for (int i = 0; i < 9; i++) {
  
   display.println(yoString[i+1])+(myString[i+1]);
   display.println(yoString[i+2]);(myString[i]);   
   display.println(yoString[i+3]);(myString[i]);
   display.println(yoString[i+4]);(myString[i]);     
   display.println(yoString[i+5]);(myString[i]);   
   display.println(yoString[i+6]);(myString[i]);
   display.println(yoString[i+7]);(myString[i]);  
  display.display();
  delay(2000);
  display.clearDisplay();

this part does part of what i want in that it displays the times in a column, but i can't get the code to add the destinations, as you can see i've tried several ways of doing this but none seem to work.

anon73444976 · April 29, 2022, 3:01pm

You haven't written any code to display the destinations.
And the indices for the times are out of bounds.

jremington · April 29, 2022, 3:03pm

The above does nothing. What did you intend it to do?

qwilpen · April 29, 2022, 3:11pm

sorry part of sketch not developed there i have just amended to show

   display.print(yoString[i+1]);display.print(" ");display.println(myString[i+1]);
   display.print(yoString[i+2]);display.print(" ");display.println(myString[i+2]);   
   display.print(yoString[i+3]);display.print(" ");display.println(myString[i+4]);
   display.print(yoString[i+4]);display.print(" ");display.println(myString[i+7]);     
   display.print(yoString[i+2]);display.print(" ");display.println(myString[i+6]);   
   display.print(yoString[i+3]);display.print(" ");display.println(myString[i+2]);
   display.print(yoString[i+1]);display.print(" ");display.println(myString[i+3]);

which gets me closer now just have to random it.

qwilpen · April 29, 2022, 3:15pm

it was supposed to be used to select from string but i realise i missed the +1 etc off the end.

thanks

jremington · April 29, 2022, 3:29pm

Still does nothing.

And the indices probably go out of bounds. Post ALL of the revised code.

qwilpen · April 29, 2022, 3:47pm

Latest version of sketch


#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SH110X.h>

/* Uncomment the initialize the I2C address , uncomment only one, If you get a totally blank screen try the other*/
#define i2c_Address 0x3c //initialize with the I2C addr 0x3C Typically eBay OLED's
//#define i2c_Address 0x3d //initialize with the I2C addr 0x3D Typically Adafruit OLED's

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 64 // OLED display height, in pixels
#define OLED_RESET -1   //   QT-PY / XIAO
Adafruit_SH1106G display = Adafruit_SH1106G(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

char *myString[]={"London","Birmingham","Manchester","Munich","Berlin","Hamburg","Paris","Madrid","Rome","Amsterdam","Brussells",};
char *yoString[]={"10:15","10:20","10:25","10:30","11:15","11:25","11:35",};
void setup()   {

  Serial.begin(9600);
  delay(250); // wait for the OLED to power up
  display.begin(i2c_Address, true); // Address 0x3C default
  display.display();
  delay(2000);
  display.clearDisplay();
}
  
void loop()
{

  display.setTextSize(1.5);
  display.setTextColor(SH110X_WHITE);
  display.setCursor(0, 0);
  display.println("       ARRIVALS");
  display.setTextSize(1);
  display.println("10:20 Stutgartd");
  display.println("10:43 London");
  display.println("10:50 Hamburg");
  display.println("11:02 Paris");
  display.println("11:13 Rome");
  display.print("11:26"); display.println(" Berlin");
  display.display();
  delay(2000);
  display.clearDisplay();


  // text display tests
//  display.setTextSize(1.5);
//  display.setTextColor(SH110X_WHITE);
//  display.setCursor(0, 0);
//  display.println("       DEPARTURES");
//  display.setTextSize(1);
//  display.println("12:20 2Stutgartd");
//  display.println("12:43 2London");
//  display.println("12:50 2Hamburg");
//  display.println("13:02 2Paris");
//  display.println("13:13 2Rome");
//  display.print("13:26"); display.println(" 2Berlin");
//  display.display();
//  delay(2000);
//  display.clearDisplay();

  display.setTextSize(1.5);
  display.setTextColor(SH110X_WHITE);
  display.setCursor(0, 0);
  display.println("       DEPARTURES");
  display.setTextSize(1);
 
  for (int i = 0; i < 9; i++) {
  
   display.print(yoString[i+1]);display.print(" ");display.println(myString[i+1]);
   display.print(yoString[i+2]);display.print(" ");display.println(myString[i+2]);   
   display.print(yoString[i+3]);display.print(" ");display.println(myString[i+4]);
   display.print(yoString[i+4]);display.print(" ");display.println(myString[i+7]);     
   display.print(yoString[i+4]);display.print(" ");display.println(myString[i+6]);   
   display.print(yoString[i+3]);display.print(" ");display.println(myString[i+2]);
   display.print(yoString[i+1]);display.print(" ");display.println(myString[i+3]);
  display.display();
  delay(2000);
  display.clearDisplay();

 }
 }

jremington · April 29, 2022, 3:51pm

The indices of yoString and myString go out of bounds, so expect garbage on the display and perhaps program crashes.

qwilpen · April 29, 2022, 3:57pm

i'm sure there will be issues as i am still learning but so far have got this.

jremington · April 29, 2022, 3:57pm

Well, have fun!

system · October 26, 2022, 3:57pm

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Chars, strings and oled help please

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