large array compiler error - Trying to load image into Flash

Projects Programming
1

All,

I am trying to load Flash of Mega 2560 (with 3.2 inch LCD) with a roughly 320x213 image. I try the following segments, and get

sketch_dec16a:11: error: size of array 'myInts' is too large
sketch_dec16a:13: error: size of array 'myInts2' is too large

Board is set correctly in Arduino Sketch. if I move the array size to apps 16000, it compiles and works. Looking for a way to have a few images sent in the executable. (no flash card right now). If I move the size down, everything compiles and downloads just fine. However, it doesn't work if I break it up into 16k chunks to get to the 68k (for the image size)

Suggestions?

#include <UTFT.h>
#include <avr/pgmspace.h>
#include "Arduino.h"

#define arraysize 17000

prog_uint16_t myInts[320][213] PROGMEM;

prog_uint16_t myInts2[arraysize] PROGMEM;

2

I suspect the Mega uses 16 bit pointer types which cannot address more than 64KB,
BTW your arrays are of 16bit ints, not chars, you are asking for 136kB, not 68kB

3

16 bits per pixel is quite extravagant . Is it a colour display, and if so what colour depth does your image need to have?

4

I just used the image converter on http://www.henningkarlsen.com/

If 64k, I should be able to go to 320 x 100, right ? (16 bit) It is bombing after roughly 155x103.
I don't need 16 bit depth. Just trying to put a few images on the display using memory.
Better converter?

#define arraysize 32000
prog_uint8_t myInts2[arraysize] PROGMEM;
is the max that will compile at 8 bit.

Thank you,

Peter

5

Array indices limited to int16 isn't unlikely on an 8 bit processor with 8K of SRAM. Suspect
it needs to be broken up to be stored.

6

Apparently there are two separate limits:

  1. The index of arrays is defined to be a signed int, so no array can have more than 32768 things in it.
  2. The total size of the array cannot exceed 64k bytes.

http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=58517

7

drewesp:
All,

I am trying to load Flash of Mega 2560 (with 3.2 inch LCD) with a roughly 320x213 image. I try the following segments, and get

Storing a bitmap should require 8 bit variables, like this:

static const uint8_t bitmap[] PROGMEM = {
        0x00, 0xff, 0x00, 0xff, etc........ // bitmap data
};

Using 16 bits is a waste of space.

A 320 by 213 array is 68160 bytes (a bit larger than 64K). The Mega uses a 16 bit pointer for PROGMEM, so it won't be able to address the entire array.

Break it into two bitmaps, then access each one for 1/2 of the image bitmap.

If all your data takes up more than 64K of flash, you may need to use pgm_read_byte_far() to get at them.

Good luck.

8

westfw:
Apparently there are two separate limits:
1) The index of arrays is defined to be a signed int, so no array can have more than 32768 things in it.
2) The total size of the array cannot exceed 64k bytes.

http://www.avrfreaks.net/index.php?name=PNphpBB2&file=viewtopic&t=58517

I've placed around 50K chunks of data in flash and was able to sequentially access all of them (which it seems I should not be able to if the pointer is SIGNED).

I used static const uint8_t bitmap[] PROGMEM = { ....~50 k of data .... };

and then pgm_read_byte (bitmap + x); where "x" was a uint16_t and it worked fine.

Strange......

9

Salve a tutti,
non sono riuscito a capire come caricare un'immagine sul display TFT touchscreen,
Devo utilizzare la seguente libreria:
prog_uint16_?

Fatemi sapere grazie

F.N.

10

Krupski:
I've placed around 50K chunks of data in flash and was able to sequentially access all of them (which it seems I should not be able to if the pointer is SIGNED).

I used static const uint8_t bitmap[] PROGMEM = { ....~50 k of data .... };

Not using Arduino and GCC you didn't. It has a maximum of 32768 bytes, not elements per addressable object regardless of what those AVRFreaks think, try and declare these arrays bigger:

char a[ 32767 ];
short b[ 16383 ];
int c[ 16383 ];
long d[ 8191 ];
long long e[ 4095 ];
float f[ 8191 ];
double g[ 8191 ];

http://arduino.land/FAQ/content/6/7/en/what-is-the-maximum-number-of-elements-an-array-can-have.html