at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 54

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

Bootloader Description
Entry points
Boot Process Description
Hardware boot process request
detection
Communication link detection
7663B–8051–03/07
PSEN=0
Yes
RESET
EA=1
Communication link
detector / initialiser
PC = RM0 @0x0000h
After reset only one bootloader entry point is possible. This entry point stands at
address 0x0000 of the boot ROM memory. This entry point executes the boot process of
the bootloader.
The bootloader entry point can be selected through two processes :
At reset, if the hardware conditions are applied, the bootloader entry point is accessed
and executed.
At reset, if the hardware conditions are not set and the BRV2-0 is programmed ‘011’, the
bootloader entry point is accessed and the bootprocess is started.
The boot process consists in three main operations :
•
•
•
The hardware boot process request is detected when the hardware conditions (under
reset, EA=1 and PSEN=0) are received by the processor or when no hardware condition
is applied and the BRV2:0 is configured ‘011’.
Two interfaces are available for ISP :
•
•
Start Bootloader
No
The hardware boot process request detection
The communication link detection (Uart or OCD)
The start-up of the bootloader
UART0
OCD UART
BRV=’011’
Yes
No
BRV=’100’
Yes
No
BRV=’101’
Yes
Start Application
No
BRV=’110’
Yes
No
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