static unsigned char sprite_bell[] = {
    0b00000001, 0b10000000,
    0b00000010, 0b01000000,
    0b00001111, 0b11110000,
    0b00010000, 0b00001000,
    0b00100000, 0b00100100,
    0b00100000, 0b00110100,
    0b00100000, 0b00110100,
    0b00100000, 0b00110100,
    0b00100000, 0b00110100,
    0b00100000, 0b00110100,
    0b00100000, 0b00000100,
    0b01000000, 0b11111010,
    0b01000000, 0b00000010,
    0b00111111, 0b11111100,
    0b00000100, 0b00100000,
    0b00000011, 0b11000000
};