ATtiny15L
48
Memory Programming
Program and Data Memory Lock Bits
The ATtiny15L MCU provides two Lock bits which can be left unprogrammed “1” or can be programmed “0” to obtain the
additional features listed in Table 22
.
The Lock bits can only be erased with the Chip Erase command
.
Fuse Bits
The ATtiny15L has six Fuse bits, BODLEVEL, BODEN, SPIEN, RSTDSBL, and CKSEL1..0. All the Fuse bits are program-
mable in both High-voltage and Low-voltage Serial programming modes. Changing the Fuses does not have effect while in
programming mode.
• The BODLEVEL Fuse selects the brown-out detection level and changes the start-up times. See “Brown-out Detection”
on page 16. See Table 5, “Reset Delay Selections
,” on page 14. Default value is programmed “0”.
• When the BODEN Fuse is programed “0”, the brown-out detector is enabled. See “Brown-out Detection” on page 16.
Default value is unprogrammed “1”.
• When the SPIEN Fuse bit is programmed “0”, Low-voltage Serial Program and Data Downloading is enabled. Default
value is programmed “0”. Unprogramming this fuse while in the Low-voltage Serial programming mode, will disable
future in-system downloading attempts.
• When the RSTDISBL Fuse is programmed “0” the external reset function of pin PB5 is disabled.
Default value is
unprogrammed “1”. Programming this fuse while in the Low-voltage Serial programming mode, will disable future in-
system downloading attempts.
• CKSEL1..0 Fuses: See Table 5, “Reset Delay Selections
,” on page 14 for which combination of CKSEL1..0 to use.
Default value is “00”, 64 ms + 18 CK.
The status of the Fuse bits is not affected by Chip Erase.
Note:
1. If the RSTDISBL Fuse is programmed, then the programming hardware should apply +12V to PB5 while the ATtiny15L is in
Power-on Reset. If not, the part can fail to enter programming mode caused by drive contention on PB0 and/or PB5.
Signature Bytes
All Atmel microcontrollers have a three-byte signature code which identifies the device.
The three bytes resides in a separate address space, and for the ATtiny15L they are:
1.
$000 : $1E (indicates manufactured by Atmel)
2.
$001 : $90 (indicates 1Kb Flash memory)
3.
$002 : $06 (indicates ATtiny15L device when $001 is $90)
Calibration Byte
The ATtiny15L 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. To make use of this byte, it should be read from this location and written into the nor-
mal Flash program memory.
Table 22.
Lock Bit Protection Modes
Memory Lock Bits
Protection Type
Mode
LB1
LB2
1
1
1
No memory lock features enabled.
2
0
1
Further programming of the Flash and EEPROM is disabled.
3
0
0
Same as mode 2, but verify is also disabled.
