ATtiny87 Atmel Corporation, ATtiny87 Datasheet - Page 220

• Manufacturer Part Number: ATtiny87
• Manufacturer: Atmel Corporation

Specifications of ATtiny87

• Flash (kbytes): 8 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 16 MHz
• Cpu: 8-bit AVR
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 16
• Usb Speed: No
• Usb Interface: No
• Spi: 2
• Twi (i2c): 1
• Uart: 1
• Lin: 1
• Graphic Lcd: No
• Video Decoder: No
• Camera Interface: No
• Adc Channels: 11
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Resistive Touch Screen: No
• Temp. Sensor: Yes
• Crypto Engine: No
• Sram (kbytes): 0.5
• Eeprom (bytes): 512
• Self Program Memory: YES
• Dram Memory: No
• Nand Interface: No
• Picopower: No
• Temp. Range (deg C): -40 to 85
• I/o Supply Class: 1.8 to 5.5
• Operating Voltage (vcc): 1.8 to 5.5
• Fpu: No
• Mpu / Mmu: no / no
• Timers: 2
• Output Compare Channels: 3
• Input Capture Channels: 1
• Pwm Channels: 9
• 32khz Rtc: Yes
• Calibrated Rc Oscillator: Yes

20.2.2
20.2.3
220
ATtiny87/ATtiny167
EEPROM Write Prevents Writing to SPMCSR
Reading the Fuse and Lock Bits from Software
• Bit 0 – SPMEN: Self Programming Enable
This bit enables the SPM instruction for the next four clock cycles. If written to one together
with either SIGRD, CTPB, RFLB, PGWRT, or PGERS, the following SPM instruction will have
a special meaning, see description above. If only SPMEN is written, the following SPM instruc-
tion will store the value in R1:R0 in the temporary page buffer addressed by the Z-pointer. The
LSB of the Z-pointer is ignored. The SPMEN bit will auto-clear upon completion of an SPM
instruction, or if no SPM instruction is executed within four clock cycles. During Page Erase
and Page Write, the SPMEN bit remains high until the operation is completed.
Writing any other combination than “10 0001
b
Note:
Note that an EEPROM write operation will block all software programming to Flash. Reading
the Fuses and Lock bits from software will also be prevented during the EEPROM write opera-
tion. It is recommended that the user checks the status bit (EEPE) in the EECR Register and
verifies that the bit is cleared before writing to the SPMCSR Register.
It is possible to read both the Fuse and Lock bits from software. To read the Lock bits, load the
Z-pointer with 0x0001 and set the RFLB and SPMEN bits in SPMCSR. When an LPM instruc-
tion is executed within three CPU cycles after the RFLB and SPMEN bits are set in SPMCSR,
the value of the Lock bits will be loaded in the destination register. The RFLB and SPMEN bits
will auto-clear upon completion of reading the Lock bits or if no LPM instruction is executed
within three CPU cycles or no SPM instruction is executed within four CPU cycles. When
RFLB and SPMEN are cleared, LPM will work as described in the Instruction set Manual.
The algorithm for reading the Fuse Low byte is similar to the one described above for reading
the Lock bits. To read the Fuse Low byte, load the Z-pointer with 0x0000 and set the RFLB
and SPMEN bits in SPMCSR. When an LPM instruction is executed within three cycles after
the RFLB and SPMEN bits are set in the SPMCSR, the value of the Fuse Low byte (FLB) will
be loaded in the destination register as shown below. See
detailed description and mapping of the Fuse Low byte.
Similarly, when reading the Fuse High byte (FHB), load 0x0003 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 Fuse High byte will be loaded in the destination register as shown
below. See
byte.
Bit
Rd (Z=0x0001)
Bit
Rd (Z=0x0000)
Bit
Rd (Z=0x0003)
” or “00 0001
Only one SPM instruction should be active at any time.
Table 21-4 on page 226
b
” in the lower six bits will have no effect.
FHB7
FLB7
7
–
7
7
FHB6
FLB6
6
6
6
–
FHB5
FLB5
5
5
–
5
for detailed description and mapping of the Fuse High
FHB4
FLB4
4
–
4
4
b
”, “01 0001
FHB3
FLB3
3
–
3
3
b
”, “00 1001
FHB2
FLB2
2
–
2
2
Table 21-5 on page 227
FHB1
b
FLB1
LB2
”, “00 0101
1
1
1
FHB0
FLB0
LB1
8265B–AVR–09/10
0
0
0
b
”, “00 0011
for a