Latching of fuses, Signature bytes, Calibration byte – Rainbow Electronics ATmega8515L User Manual
Page 177: Table 84, Atmega8515(l)
177
ATmega8515(L)
2512A–AVR–04/02
Notes:
1. The default value of SUT1..0 results in maximum start-up time. See Table 13 on page
36 for details.
2. The default setting of CKSEL3..0 results in internal RC Oscillator @ 1 MHz. See
Table 5 on page 32 for details.
The status of the Fuse bits is not affected by Chip Erase. Note that the Fuse bits are
locked if Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the
Lock bits.
Latching of Fuses
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.
Signature Bytes
All Atmel microcontrollers have a 3-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 ATmega8515 the signature bytes are:
1.
$000: $1E (indicates manufactured by Atmel).
2.
$001: $93 (indicates 8KB Flash memory).
3.
$002: $06 (indicates ATmega8515 device when $001 is $93).
Calibration Byte
The ATmega8515 has a one-byte calibration value for the internal RC Oscillator. This
byte resides in the high byte of address $000 in the signature address space. During
reset, this byte is automatically written into the OSCCAL Register to ensure correct fre-
quency of the calibrated RC Oscillator.
Table 84. Fuse Low Byte
Fuse Low Byte
Bit no
Description
Default value
BODLEVEL
7
Brown-out Detector trigger
level
1 (unprogrammed)
BODEN
6
Brown-out Detector enable
1 (unprogrammed, BOD
disabled)
SUT1
5
Select start-up time
1 (unprogrammed)
SUT0
4
Select start-up time
0 (programmed)
CKSEL3
3
Select Clock source
0 (programmed)
CKSEL2
2
Select Clock source
0 (programmed)
CKSEL1
1
Select Clock source
0 (programmed)
CKSEL0
0
Select Clock source
1 (unprogrammed)