at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 32

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

Bootprocess
Figure 3. Boot Reset vector configuration
32
AT89C51RE2
EA pin
0
1
The BRV2-0 bits of the FSB (see Table 2 on page 9), the EA pin value upon reset and
the presence of the external hardware conditions, allow to modify the default reset vec-
tor of the AT89C51RE2.
The Hardware conditions (EA = 1, PSEN = 0) during the Reset falling edge force the on-
chip bootloader execution. This allows an application to be built that will normally exe-
cute the end user’s code but can be manually forced into default ISP operation. The
hardware conditions allows to force the enter in ISP mode whatever the configurations
bits.
Hardware conditions
YES
NO
X
BRV2-0
1 1 1
1 1 0
1 0 1
1 0 0
0 1 1
0 1 0
0 0 1
0 0 0
X
X
(FM0 at address 0x0000 with bank 0 mapped)
RM0 at address 0x0000 (ATMEL Bootloader)
RM0 at address 0x0000 (ATMEL Bootloader)
FM0 at address 0x0000 with bank0 mapped
FM0 at address 0xFFFC in Bank 0
FM0 at address 0xFFFC in Bank 1
FM0 at address 0xFFFC in Bank 2
External Code at address 0x0000
MCU reset vector
Reserved
7663B–8051–03/07