Storing and retrieving 11KB fixed data within program code. AVR & PIC

[LeighM]

Hmm, well the XC8 compiler manual indicates that the const will place the data in ROM space.
But ...

For baseline PIC devices, the maximum size of a single const object is 255 bytes.
However, you can define as many const objects as required provided the total size
does not exceed the available program memory size of the device.

Also it seems that PIC has to copy this into RAM before use, which makes it more like an initialized variable than a const.
Having done most of my recent "C" years on ARM, this is all coming back as a bit of a shock

[medelec35]

Hi Leigh,
It needs testing but have solved it so now compiles.
Instead of:

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const unsigned char Image1[] =

I moved char position:

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char const unsigned Image1[] =

Also it seems that PIC has to copy this into RAM before use, which makes it more like an initialized variable than a const.

I'm guessing the first is treated like a variable as you stated so uses RAM, whereas the second places it in ROM?

Having done most of my recent "C" years on ARM, this is all coming back as a bit of a shock

All of it is a shock to me, At least you know C

Thanks again for all your help, Much appreciated.

[LeighM]

Hi Martin,
Yes you are correct, bit of a typo on my part, forgetting image1 is pointer, so the pointer and data it points to can be const

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const char const Image1[] =