Fetching unsigned long values from PROGMEM Not Working

Using Arduino Programming Questions
1

This is my first post, forgive me if my format is strange or incorrect.
I've spent hours on this so far and I'm hoping someone else can see a simple mistake I'm making.

Regarding my (attached) sketch, I am simply storing some 32-bit (unsigned long) numbers in the PROGMEM area.
But when I retrieve them and Serial.print them, they're incorrect.

I expect to see this output:
0 112233
1 44556677
2 8899AABB
3 CCDDEEFF

But I see this:
0 2233
1 6677
2 FFFFAABB
3 FFFFEEFF

It appears that for some reason, Bit31 is acting as a sign and only the lower 16-bits are correctly reported. But these are supposed to be unsigned longs.

Can anyone see a problem with what I'm doing or have a solution?
Thank you so much!!!

sketch_jan06a.ino (610 Bytes)

2

Sorry, I am also pasting the code here for easier reference:

#define ARRAY_SIZE (4)
const unsigned long u4_LOOKUP_TABLE[ARRAY_SIZE] PROGMEM =
{
0x00112233,
0x44556677,
0x8899AABB,
0xCCDDEEFF,
};
unsigned char u1_s_idx;
unsigned long u4_s_lookupValue;

void setup()
{
Serial.begin(115200);

for(u1_s_idx = 0; u1_s_idx < ARRAY_SIZE; u1_s_idx ++)
{
u4_s_lookupValue = (unsigned long*)pgm_read_dword(&(u4_LOOKUP_TABLE[u1_s_idx]));

Serial.print(u1_s_idx ); Serial.print(' ');
Serial.print(u4_s_lookupValue, HEX); Serial.print('\n');
}
}

void loop()
{
;
}

3 
      u4_s_lookupValue = [color=red](unsigned long*)[/color]pgm_read_dword(&(u4_LOOKUP_TABLE[u1_s_idx]));

You need to get rid of the cast to pointer. It's NOT a pointer, and pointers on AVR are only 16bits, so you're throwing away the high bytes (and then sign-extending, apparently.)

      u4_s_lookupValue = pgm_read_dword(&(u4_LOOKUP_TABLE[u1_s_idx]));
4

Wow. Excellent. Thank you so much for your help, I very much appreciate it!!

5