problem with using String()

Question

I'm new to arduino and currently trying to build a small program with multiple screens and buttons and a counter. when I try to convert a int to a chararray it messes up the world. with out it what I have so far works any suggestions on what I'm doing wrong? with the code to convert the int to chararray it seems to lock up the program when I switch from main screen to options screen then back. I put some serial outs to narrow down where the flaw is.

My results are it is between

 test1++; Serial.println("oops check");
 str = String(test1); Serial.println("sanity check"); 

Something hangs it up after it outputs "oops check" so I figure it is str = String(test1); I have been searching and trying every thing I can find. if someone can give me a kick in the right direction. I'm usin the tft seedstudio v2 display with the modified tft library for text direction.

 /* 
 Title: TouchScreenButton Tutorial
 About: Example/tutorial file for how to create buttons with the TouchScreenButtons library
 Author: Richard Kirkpatrick
 Date: 20 July 2014
*/
// Libraries
#include <stdint.h> 
#include <SeeedTouchScreen.h> // Library for the Seeed Studio TFT Touch Shield 
#include <TFTv2.h> // Library for the Seeed Studio TFT Touch Shield 
#include <TouchScreenGeometry.h> // Library for drawing geometric shapes for the touch screen
#include <TouchScreenStrings.h> // Library for drawing strings for the touch screen
#include <TouchScreenButtons.h> // Library for creating buttons for the keypad
#include <SPI.h>
//Measured ADC values for (0,0) and (210-1,320-1)
//TS_MINX corresponds to ADC value when X = 0
//TS_MINY corresponds to ADC value when Y = 0
//TS_MAXX corresponds to ADC value when X = 240 -1
//TS_MAXY corresponds to ADC value when Y = 320 -1
#define TS_MINX 890*2
#define TS_MAXX 116*2
#define TS_MINY 913*2
#define TS_MAXY 83*2
TouchScreen ts = TouchScreen(XP, YP, XM, YM);
// Global variables
String str;
Button bigButton;
Button buttons[12];
Button reset;
Button back;
int screen = 1;
int test;
int test1 = 0;
char b[5];
void setup() 
{
 // Initializes the TFT library
 Tft.TFTinit(); 
 // Start the Serial port. Used to determine which button was pressed.
 Serial.begin(9600); 
 screen = 1; 
}
void loop()
{ test1++; Serial.println("oops check");
 str = String(test1); Serial.println("sanity check");
 str.toCharArray(b,5);
 Serial.print("screen = "); Serial.print(screen );
 // A point objects holds x, y, and z coordinates
 Point p = ts.getPoint(); 
 p.x = map(p.x, TS_MINX, TS_MAXX, 240, 0);
 p.y = map(p.y, TS_MINY, TS_MAXY, 320, 0);
 // Determine which button was pressed
 int userInput = -1; // -1 means no button is pressed
 if (p.z > __PRESURE){ 
 userInput = getButtonNumber(p.x, p.y); 
 Serial.print("X = "); Serial.print(p.x);
 Serial.print("\tY = "); Serial.print(p.y);
 Serial.print("\tPressure = "); Serial.println(p.z);
 }
 // Show which button was pressed on the Serial monitor
 if (userInput == 13) {
 Serial.println("Options button was pressed!");
 bigButton.buttonDisplay();
 }
 if (userInput == 15) {
 Serial.println("back button was pressed!");
 back.buttonDisplay();
 }
 else if (userInput == 14) {
 Serial.println("reset button was pressed!");
 reset.buttonDisplay();
 } 
 delay(10);
if (screen == 1) {
if (test == 1) {
 Tft.fillScreen(); }
 Serial.print("test1 = "); Serial.println(b); // prints "Hello String"
 // Draw reset button
 reset.setValues(75, 215, 35, 100);
 reset.draw();
 // Draw the big button
 bigButton.setValues(15, 185, 35, 130);
 bigButton.draw();
Tft.drawRectangle(40, 15, 70, 120,BLUE);
Tft.setDisplayDirect(UP2DOWN);
 Tft.drawString("Frays",100,20,2,RED);
 Tft.drawString(b,65,20, 2, BLUE);
 //Draw reset buttons text
 TouchScreenString resetText("RESET", 100, 230, 2, RED);
 resetText.drawText();
 Serial.println("a"); // prints "Hello String"
 // Draw the big button's text
 TouchScreenString bigButtonText("OPTIONS", 40, 197, 2, WHITE);
 bigButtonText.drawText();
test = 0;
}
if (screen == 2) {
 if (test == 0) {Tft.fillScreen();}
 // draw back button
 back.setValues(15, 15, 35, 85);
 back.draw();
Tft.setDisplayDirect(UP2DOWN);
 // Draw the back button's text
 TouchScreenString backText("BACK", 40, 30, 2, WHITE);
 backText.drawText();
test = 1;
}}
// Gets which button was pressed. If no button is pressed, -1 is returned.
int getButtonNumber(int xInput, int yInput)
{
if (screen == 1) {
 if (bigButton.isPressed(xInput, yInput)) {
 screen = 2;
 return 13; // Signifies big button was pressed
 } }
 if (screen ==2) {
 if (back.isPressed(xInput, yInput)) {
 screen = 1;
 return 15; // Signifies big button was pressed
 }}
 if (screen == 1) {
 if (reset.isPressed(xInput, yInput)) {
 test1 = 0;
 return 14; // Signifies reset button was pressed
 }}
 else {
 return -1; // Signifies no button was pressed
 }
}

• bladepanthera: When you say 'hangs it up', is there no error output? Have you tried printing String(test1) to see what happens? From what you've said I guess 'oops check' printed out but 'sanity check' didn't?
• Michael: when I say it hangs up the touch screen stops responding and the serial output stops with "oops check" being last thing printed. when this happens have to reboot processor. no I have not tried printing String(test1) will see if I can do that now.
• Michael: just tried printing (test1) and (str) both will print but it still locks up when it goes to execute the line str = String(test1); I can't figure why. the way the screen acts it's like the program corrupts. I'm getting stray lines and shapes on the screen at times.
• Michael: just tried removing all serial prints from the program and even removed str.toCharArray(b,5); and test1++ and it still fragments. which I find odd. if I set test1=20 it locks up. am I still running out of ram? it just doesn't seem right. I know I'm over looking something. guess I will go back to trying to get the drawnumber to work again.
• bladepanthera: Hmm weird. Have you tried commenting it all out then uncommenting it bit by bit? Then you can pin point exactly which line is causing problems. It is a problem with stuff that is happening before the while loop starts by the sounds of it, although considering you are using library functions for the stuff other than initialisations, I have no idea why it doesn't work. Do you have the correct library versions for the hardware you are using?

Answer 1

My guess is you are running out of RAM. Your various string constants alone take up 202 bytes. Then there is this:

 test1++; 
 str = String(test1); 
 str.toCharArray(b,5);

That is very likely to fragment memory, as test1 gets larger and larger. So you are fragmenting RAM, of which you don't have much to start with.

Why are you even converting test1 into a String object? And then converting it back into an array?

The array b can only hold 4 digits as it needs one byte for the trailing null-terminator.

I suggest you stop doing that String stuff, and also use the F() macro like this ...

Change:

 Serial.println("Options button was pressed!");

to:

 Serial.println(F("Options button was pressed!"));

Ditto for all the other places you are displaying stuff.

• bladepanthera: I agree with this solution, too. Although I find it curious that it runs out of memory during the first iteration. Printing using flash memory strings is something that I do most of the time now with my Uno/Mega, although if you're using a small micro-c there may be limited flash space to use (you probably wouldn't be printing anything then anyway as smaller devices often don't have serial ports).
• Michael: I agree it is running out of ram and fragmenting. as far as the Serial.println and all the other serial stuff I do not need. the reason for the String stuff is this. the device I'm trying to make I wanted the screen orientated so it is wider than it is tall. I can get the characters to display in the correct orientation but when I try to Tft.drawNumber(1024, 0, 0, 1, RED); the numbers are turned the right way but reads from bottom to top not left to right. can't get it to do right. this was my work around. I used to use avrgcc but been years. any suggestions?
• Michael: Thanks for the responses I'm still learning and trying to remember.