at90pwm81-16se ATMEL Corporation, at90pwm81-16se Datasheet - Page 237

• Manufacturer Part Number: at90pwm81-16se
• Description: 8-bit Avr Microcontroller With 8k Bytes In- System Programmable Flash
• Manufacturer: ATMEL Corporation

21.5
7734M–AVR–03/10
Entering the Boot Loader Program
ilarly, the general Read/Write Lock (Lock Bit mode 1) does not control reading nor writing by LPM/SPM,
if it is attempted.
Table 21-2.
Note:
Table 21-3.
Note:
Entering the Boot Loader takes place by a jump or call from the application program. This may be initi-
ated by a trigger such as a command received via SPI interface. Alternatively, the Boot Reset Fuse can be
programmed so that the Reset Vector is pointing to the Boot Flash start address after a reset. In this case,
the Boot Loader is started after a reset. After the application code is loaded, the program can start execut-
ing the application code. Note that the fuses cannot be changed by the MCU itself. This means that once
the Boot Reset Fuse is programmed, the Reset Vector will always point to the Boot Loader Reset and the
fuse can only be changed through the serial or parallel programming interface.
Table 21-4.
Note:
BLB0 Mode
BLB1 Mode
BOOTRST
1
2
3
4
1
2
3
4
1
0
1. “1” means unprogrammed, “0” means programmed
1. “1” means unprogrammed, “0” means programmed
1. “1” means unprogrammed, “0” means programmed
Boot Lock Bit0 Protection Modes (Application Section)
Boot Lock Bit1 Protection Modes (Boot Loader Section)
Boot Reset Fuse
BLB02
BLB12
Reset Address
Reset Vector = Application Reset (address 0x0000)
Reset Vector = Boot Loader Reset (see
1
1
0
0
1
1
0
0
BLB01
BLB11
(1)
1
0
0
1
1
0
0
1
Protection
No restrictions for SPM or LPM accessing the Application section.
SPM is not allowed to write to the Application section.
SPM is not allowed to write to the Application section, and LPM
executing from the Boot Loader section is not allowed to read from the
Application section. If Interrupt Vectors are placed in the Boot Loader
section, interrupts are disabled while executing from the Application
section.
LPM executing from the Boot Loader section is not allowed to read
from the Application section. If Interrupt Vectors are placed in the
Boot Loader section, interrupts are disabled while executing from the
Application section.
Protection
No restrictions for SPM or LPM accessing the Boot Loader section.
SPM is not allowed to write to the Boot Loader section.
SPM is not allowed to write to the Boot Loader section, and LPM
executing from the Application section is not allowed to read from the
Boot Loader section. If Interrupt Vectors are placed in the Application
section, interrupts are disabled while executing from the Boot Loader
section.
LPM executing from the Application section is not allowed to read
from the Boot Loader section. If Interrupt Vectors are placed in the
Application section, interrupts are disabled while executing from the
Boot Loader section.
Table 21-7 on page
(1)
(1)
246)
AT90PWM81
237