[avr-gcc-list] Using flash memory for storing large look up tables

[dhananjay deshpande]

Hi,

I am learning to use AVRGCC. I am using it in AVRSTUDIO.

I have a difficulty for my application of "sunset switch on- sunrise switch off relay", which requires a look up table of ~730 integers to be stored in the program. I do not have any other option but to save this table in program memory.

I am using ATMEGA 8535L, I am using assynchronous timer and external 32kHz crystal for realtime keeping.

Question is how to store and retrieve the table contents.

I started with a little short table of 2 months timing for sunset and sunrise.

the code was as follows

for storing the sunset and sunrise timings

const int __attribute__((section(".text"))) sunrise[2][31]={
                           {601,602,603,604,605,606,607,608,609,610,
                            611,612,613,614,615,616,617,618,619,620,
       621,622,623,624,625,626,627,628,629,630,631}
       ,{                                         }
           };
const int __attribute__((section(".text"))) sunset[2][31]= {
                            {1801,1802,1803,1804,1805,1806,1807,1808,1809,1810,
        1811,1812,1813,1814,1815,1816,1817,1818,1819,1820,
        1821,1822,1823,1824,1825,1826,1827,1828,1829,1830,1831}
         {          }                  };

 

for retrieving

 

todayssunset=sunset[t.month][t.date] ;  //t is a structure .

 

This retrieving doesnot work if I use __attribute__((section(".text"))).

 

If I do not use section(".text") attribute, the table is stored in data space which is insufficient . Is there any way out?  please help.

Thanks in advance     

 

 

avr_learner

 

 

 

 

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