Problem with large data array in ROM and #rom

[giuseppe]

On my PIC24FJ256GA106 project I've defined a large data array for character's map for my LCD graphic display, and I've defined it as constant

[Ttelmah]

How can you say:
"The value obtained by MappaCaratteri[index] (when index = 0) is the previous array value [index -1]". There is not and cannot be an entry for array-1. Doesn't make sense.

However there are inherent faults in what you do, that may be causing you problems:

index = n*5;

n is an int8. So is '5', so this is going to wrap into the wrong part of the array when n is greater than 51.

index = n*5L;

or

index = (int16)n*5;

are needed to ensure the arithmetic does not overflow.

#ROM, tells the compiler to put an array at an address in ROM. If you do it inside a block of code, a segment will be created, but if you do it outside (as for a global variable), the memory space won't be reserved. Reserve the memory space with an #ORG to avoid it being overwritten.

Best Wishes

[giuseppe]

Hi!
I've fixed this potential bug, but I was sure the n cannot be greater than 24.

[jeremiah]

In your last example, you created a ram array instead of a rom array by mistake. My guess is that when main goes to initialize the ram array, the code needed pushes the size of main past the allowed boundary. Remember that #org is for organizing ROM, not RAM

[giuseppe]

[Ttelmah]

The way to declare a const array at a location, is:

[giuseppe]

OK, thank you, Now It works... I've some problems with memory organization but I hope to solve also it.