ATtiny261 Atmel Corporation, ATtiny261 Datasheet - Page 168

• Manufacturer Part Number: ATtiny261
• Manufacturer: Atmel Corporation

Specifications of ATtiny261

• Flash (kbytes): 2 Kbytes
• Pin Count: 20
• Max. Operating Frequency: 20 MHz
• Cpu: 8-bit AVR
• # Of Touch Channels: 4
• Hardware Qtouch Acquisition: No
• Max I/o Pins: 16
• Ext Interrupts: 16
• Usb Speed: No
• Usb Interface: No
• Spi: 1
• Twi (i2c): 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): 0.12
• Eeprom (bytes): 128
• 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: 6
• Input Capture Channels: 1
• Pwm Channels: 6
• 32khz Rtc: No
• Calibrated Rc Oscillator: Yes

17.7
17.8
168
Preventing Flash Corruption
Programming Time for Flash when Using SPM
ATtiny261/461/861
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
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
Byte.
During periods of low V
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. 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.
Flash corruption can easily be avoided by following these design recommendations (one is
sufficient):
The calibrated RC Oscillator is used to time Flash accesses.
gramming time for Flash accesses from the CPU.
Table 17-1.
Note:
Bit
Rd
Bit
Rd
Flash write (Page Erase, Page Write, and
write Lock bits by SPM)
1. Keep the AVR RESET active (low) during periods of insufficient power supply voltage.
2. Keep the AVR core in Power-down sleep mode during periods of low V
This can be done by enabling the internal Brown-out Detector (BOD) if the operating
voltage matches the detection level. If not, an external low V
can be used. If a reset occurs while a write operation is in progress, the write operation
will be completed provided that the power supply voltage is sufficient.
vent the CPU from attempting to decode and execute instructions, effectively protecting
the SPMCSR Register and thus the Flash from unintentional writes.
1. Minimum and maximum programming time is per individual operation.
Table 18-4 on page 171
Table 18-3 on page 171
SPM Programming Time
FHB7
FEB7
Symbol
7
7
CC
FHB6
FEB6
, the Flash program can be corrupted because the supply voltage is
6
6
for detailed description and mapping of the Fuse High Byte.
FHB5
FEB5
for detailed description and mapping of the Fuse Extended
5
5
(1)
Min Programming Time
FHB4
FEB4
4
4
3.7 ms
FHB3
FEB3
3
3
FHB2
FEB2
Table 17-1
2
2
CC
reset protection circuit
Max Programming Time
FHB1
FEB1
1
1
shows the typical pro-
CC
. This will pre-
4.5 ms
FHB0
FEB0
0
0
2588E–AVR–08/10