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Latching of Fuses
Signature Bytes
Calibration Byte
Page Size
Parallel Programming
Parameters, Pin
Mapping, and
Commands
Signal Names
1477G–AVR–03/05
The fuse values are latched when the device enters programming mode and changes of
the fuse values will have no effect until the part leaves programming mode. This does
not apply to the EESAVE Fuse which will take effect once it is programmed. The fuses
are also latched on Power-up in normal mode.
All Atmel microcontrollers have a three-byte signature code which identifies the device.
This code can be read in both serial and parallel mode, also when the device is locked.
The three bytes reside in a separate address space.
For the ATtiny26 the signature bytes are:
1. $000: $1E (indicates manufactured by Atmel).
2. $001: $91 (indicates 2KB Flash memory).
3. $002: $09 (indicates ATtiny26 device when $001 is $91).
The ATtiny26 stores four different calibration values for the internal RC Oscillator. These
bytes resides in the signature row high byte of the addresses 0x0000, 0x0001, 0x0002,
and 0x0003 for 1, 2, 4, and 8 MHz respectively. During Reset, the 1 MHz value is auto-
matically loaded into the OSCCAL Register. If other frequencies are used, the
calibration value has to be loaded manually, see "Oscillator Calibration Register – OSC-
CAL" on page 28 for details.
Table 52. No. of Words in a Page and no. of Pages in the Flash
Flash Size
1K words (2K bytes)
Table 53. No. of Words in a Page and no. of Pages in the EEPROM
EEPROM Size
Page Size
128 bytes
4 bytes
This section describes how to parallel program and verify Flash Program memory,
EEPROM Data memory, Memory Lock bits, and Fuse bits in the ATtiny26. Pulses are
assumed to be at least 250 ns unless otherwise noted.
In this section, some pins of the ATtiny26 are referenced by signal names describing
their functionality during parallel programming, see Figure 58 and Table 54. Pins not
described in the following table are referenced by pin names.
The XA1/XA0 pins determine the action executed when the XTAL1 pin is given a posi-
tive pulse. The bit coding is shown in Table 56.
When pulsing WR or OE, the command loaded determines the action executed. The dif-
ferent Commands are shown in Table 57.
Page Size
PCWORD
16 words
PC[3:0]
PCWORD
No. of Pages
EEA[1:0]
ATtiny26(L)
No. of Pages
PCPAGE
64
PC[9:4]
PCPAGE
32
EEA[7:0]
PCMSB
9
EEAMSB
7
109
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