Datasheet

221
7728G–AVR–06/10
ATtiny87/ATtiny167
Similarly, when reading the Extended Fuse byte (EFB), load 0x0002 in the Z-pointer. When an
LPM instruction is executed within three cycles after the RFLB and SPMEN bits are set in the
SPMCSR, the value of the Extended Fuse byte will be loaded in the destination register as
shown below. See Table 21-3 on page 226 for detailed description and mapping of the
Extended Fuse byte.
Fuse and Lock bits that are programmed, will be read as zero. Fuse and Lock bits that are
unprogrammed, will be read as one.
20.2.4 Reading the Signature Row from Software
To read the Signature Row from software, load the Z-pointer with the signature byte address
given in Table 20-1 on page 221 and set the SIGRD and SPMEN bits in SPMCSR. When an
LPM instruction is executed within three CPU cycles after the SIGRD and SPMEN bits are set
in SPMCSR, the signature byte value will be loaded in the destination register. The SIGRD
and SPMEN bits will auto-clear upon completion of reading the Signature Row Lock bits or if
no LPM instruction is executed within three CPU cycles. When SIGRD and SPMEN are
cleared, LPM will work as described in the Instruction set Manual.
Note: All other addresses are reserved for future use.
Bit 76543210
Rd (Z=0x0002) –––––––EFB0
Table 20-1. Signature Row Addressing
Signature Byte Z-Pointer Address
Device Signature Byte 0 0x0000
Device Signature Byte 1 0x0002
Device Signature Byte 2 0x0004
8MHz RC Oscillator Calibration Byte 0x0001
TSOFFSET - Temp Sensor Offset 0x0005
TSGAIN - Temp Sensor Gain 0x0007