33.7.12 Reading the Fuse and Lock Bits

The algorithm for reading the Fuse and Lock bits is as follows (Please refer to Programming the Flash for details on Command loading):

  1. Step A: Load Command “0000 0100”.
  2. Set OE to “0”, BS2 to “0” and BS1 to “0”. The status of the Fuse Low bits can now be read at DATA (“0” means programmed).
  3. Set OE to “0”, BS2 to “1” and BS1 to “1”. The status of the Fuse High bits can now be read at DATA (“0” means programmed).
  4. Set OE to “0”, BS2 to “1”, and BS1 to “0”. The status of the Extended Fuse bits can now be read at DATA (“0” means programmed).
  5. Set OE to “0”, BS2 to “0” and BS1 to “1”. The status of the Lock bits can now be read at DATA (“0” means programmed).
  6. Set OE to “1”.
Figure 33-5. Mapping Between BS1, BS2 and the Fuse and Lock Bits During Read