c - AVR gcc, weird array behaviour -

it's first time see this. i'm starting suspect it's hardware fault. whenever try send contents of array "test" , array larger 4 elements or initialize elements in declaration contains 0xff instead of values try initialise with.

this works fine. when read values array in while(sending them lcd , uart) both readouts consistent test values:

uint8_t i=0; uint8_t test[4] = {1,2,3,4};      while(i<5){      glcd_writedata(test[i]);      usart_transmit(test[i]);      i++;  } 

this doesn't, returns 0xff instead of test[i] value:

uint8_t i=0; uint8_t test[5] = {1,2,3,4,5};      while(i<5){      glcd_writedata(test[i]);      usart_transmit(test[i]);      i++;  } 

but works! returns proper values

uint8_t i=0; uint8_t test[6] = {1,2,3,4,5};      while(i<5){      glcd_writedata(test[i]);      usart_transmit(test[i]);      i++;  } 

this works:

uint8_t i=0; uint8_t test[5]; test[0]=1; test[1]=2; test[2]=3; test[3]=4; test[4]=5;      while(i<5){      glcd_writedata(test[i]);      usart_transmit(test[i]);      i++;      } 

it works fine when compiled on linux

i swapped out mcu different 1 , works way should. must hardware problem

in first example going out of bounds of array test[4]. running while 5 times, when array has 4 items length.