Datasheet

182
8246B–AVR–09/11
ATtiny2313A/4313
If successful, the contents of the destination register are as follows.
See section “Parallel Programming” on page 184 for more information.
20.4.2 Fuse Bit Read
The algorithm for reading fuse bytes is similar to the one described above for reading lock bits,
only the addresses are different.
To read the Fuse Low Byte (FLB), follow the below procedure:
1. Load the Z-pointer with 0x0000.
2. Set RFLB and SPMEN bits in SPMCSR.
3. Issue an LPM instruction within three clock cycles.
4. Read the FLB from the LPM destination register.
If successful, the contents of the destination register are as follows.
Refer to Table 20-5 on page 180 for a detailed description and mapping of the Fuse Low Byte.
To read the Fuse High Byte (FHB), simply replace the address in the Z-pointer with 0x0003 and
repeat the procedure above. If successful, the contents of the destination register are as follows.
Refer to Table 20-4 on page 179 for detailed description and mapping of the Fuse High Byte.
To read the Fuse Extended Byte (FEB), replace the address in the Z-pointer with 0x0002 and
repeat the previous procedure. If successful, the contents of the destination register are as
follows.
Refer to Table 20-3 on page 179 for detailed description and mapping of the Fuse Extended
Byte.
20.4.3 Device Signature Imprint Table Read
To read the contents of the device signature imprint table, follow the below procedure:
1. Load the Z-pointer with the table index.
2. Set RSIG and SPMEN bits in SPMCSR.
3. Issue an LPM instruction within three clock cycles.
Bit 76543210
Rd ––––––LB2LB1
Bit 76543210
Rd FLB7 FLB6 FLB5 FLB4 FLB3 FLB2 FLB1 FLB0
Bit 76543210
Rd FHB7 FHB6 FHB5 FHB4 FHB3 FHB2 FHB1 FHB0
Bit 76543210
Rd FEB7 FEB6 FEB5 FEB4 FEB3 FEB2 FEB1 FEB0