Signature Bytes; Calibration Byte; Page Size - Atmel ATtiny25 Manual

21.3

Signature Bytes

21.3.1 ATtiny25 Signature Bytes
21.3.2 ATtiny45 Signature Bytes
21.3.3 ATtiny85 Signature Bytes
21.4

Calibration Byte

21.5

Page Size

7598H–AVR–07/09
All Atmel microcontrollers have a three-byte signature code which identifies the device. This
code can be read in both serial and High-voltage Programming mode, also when the device is
locked. The three bytes reside in a separate address space.
1. 0x000: 0x1E (indicates manufactured by Atmel).
2. 0x001: 0x91 (indicates 2 KB Flash memory).
3. 0x002: 0x08 (indicates ATtiny25 device when 0x001 is 0x91).
1. 0x000: 0x1E (indicates manufactured by Atmel).
2. 0x001: 0x92 (indicates 4 KB Flash memory).
3. 0x002: 0x06 (indicates ATtiny45 device when 0x001 is 0x92).
1. 0x000: 0x1E (indicates manufactured by Atmel).
2. 0x001: 0x93 (indicates 8 KB Flash memory).
3. 0x002: 0x0B (indicates ATtiny85 device when 0x001 is 0x93).
Signature area of the ATtiny25/45/85 has one byte of calibration data for the internal RC Oscilla-
tor. This byte resides in the high byte of address 0x000. During reset, this byte is automatically
written into the OSCCAL Register to ensure correct frequency of the calibrated RC Oscillator.
Table 21-6. No. of Words in a Page and No. of Pages in the Flash
Device Flash Size
1K words
ATtiny25
(2K bytes)
2K words
ATtiny45
(4K bytes)
4K words
ATtiny85
(8K bytes)
Table 21-7. No. of Words in a Page and No. of Pages in the EEPROM
EEPROM
Device Size
ATtiny25 128 bytes
ATtiny45 256 bytes
ATtiny85 512 bytes
Page Size PCWORD
16 words PC[3:0]
32 words PC[4:0]
32 words PC[4:0]
Page Size PCWORD
4 bytes EEA[1:0]
4 bytes EEA[1:0]
4 bytes EEA[1:0]
ATtiny25/45/85
No. of Pages PCPAGE
64 PC[9:4]
64 PC[10:5]
128 PC[11:5]
No. of Pages PCPAGE
32 EEA[6:2]
64 EEA[7:2]
128 EEA[8:2]
PCMSB
9
10
11
EEAMSB
6
7
8
137