attiny167-esxz ATMEL Corporation, attiny167-esxz Datasheet - Page 212

• Manufacturer Part Number: attiny167-esxz
• Description: 8-bit Avr 8-bit Microcontroller Microcontroller With 16k Bytes In-system Programmable Flash And Lin Controller
• Manufacturer: ATMEL Corporation

20.2.4
20.2.5
212
ATtiny167
Reading the Signature Row from Software
Preventing Flash Corruption
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
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.
To read the Signature Row from software, load the Z-pointer with the signature byte address
given in
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.
Table 20-1.
Note:
During periods of low Vcc, the Flash program can be corrupted because the supply voltage is
too low for the CPU and the Flash to operate properly. These issues are the same as for board
level systems using the Flash, and the same design solutions should be applied.
A Flash program corruption can be caused by two situations when the voltage is too low.
•
•
Flash corruption can easily be avoided by following these design recommendations (one is
sufficient):
1. Keep the AVR RESET active (low) during periods of insufficient power supply voltage.
Bit
Rd (Z=0x0002)
First, a regular write sequence to the Flash requires a minimum voltage to operate correctly.
Secondly, the CPU itself can execute instructions incorrectly, if the supply voltage for
executing instructions is too low.
This can be done by enabling the internal Brown-out Detector (BOD) if the operating volt-
age matches the detection level. If not, an external low Vcc reset protection circuit can be
8MHz RC Oscillator Calibration Byte
All other addresses are reserved for future use.
TSOFFSET - Temp Sensor Offset
Table 20-1 on page 212
TSGAIN - Temp Sensor Gain
Device Signature Byte 0
Device Signature Byte 1
Device Signature Byte 2
Signature Row Addressing
Signature Byte
7
–
Table 21-3 on page 217
6
–
and set the SIGRD and SPMEN bits in SPMCSR. When an
5
–
for detailed description and mapping of the Extended
4
–
3
–
Z-Pointer Address
2
–
0x0000
0x0002
0x0004
0x0001
0x0003
0x0005
1
–
EFB0
7728A–AUTO–07/08
0