
173
2588F–AVR–06/2013
ATtiny261/461/861
18.4
Calibration Byte
Signature area of the ATtiny261/461/861 has one byte of calibration data for the internal RC
Oscillator. This byte resides in the high byte of address 0x000. During reset, this byte is auto-
matically written into the OSCCAL Register to ensure correct frequency of the calibrated RC
Oscillator.
18.5
Page Size
18.6
Serial Programming
Both the Flash and EEPROM memory arrays can be programmed using the serial SPI bus while
RESET is pulled to GND. The serial interface consists of pins SCK, MOSI (input) and MISO (out-
Figure 18-1. Serial Programming and Verify
Note:
If the device is clocked by the internal Oscillator, there is no need to connect a clock source to the
CLKI pin.
Table 18-7.
No. of Words in a Page and No. of Pages in the Flash
Device
Flash Size
Page Size
PCWORD
No. of Pages
PCPAGE
PCMSB
ATtiny261
1K words (2K bytes)
16 words
PC[3:0]
64
PC[9:4]
9
ATtiny461
2K words (4K bytes)
32 words
PC[4:0]
64
PC[10:5]
10
ATtiny861
4K words (8K bytes)
32 words
PC[4:0]
128
PC[11:5]
11
Table 18-8.
No. of Words in a Page and No. of Pages in the EEPROM
Device
EEPROM
Size
Page Size
PCWORD
No. of Pages
PCPAGE
EEAMSB
ATtiny261
128 bytes
4 bytes
EEA[1:0]
32
EEA[6:2]
6
ATtiny461
256 bytes
4 bytes
EEA[1:0]
64
EEA[7:2]
7
ATtiny861
512 bytes
4 bytes
EEA[1:0]
128
EEA[8:2]
8
VCC
GND
SCK
MISO
MOSI
RESET
+1.8 - 5.5V