PROGMEM char array

Projects Programming
2

try a different declaration

char charSet[]  PROGMEM = { 0x0, 0x8, 0x4, 0xc, 0x2, 0xA , 0x6, 0xE, 0x1, 0x9,0x5, 0xD, 0x3,0xB,0x7,0xF };

also try below instead of assigning to ff

Serial.print( pgm_read_byte( charSet + i ) );