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21.1 Flash Boot Loader
The Boot Loader controls initial operation after reset, and also provides the means to
accomplish programming of the Flash memory. This could be initial programming of a
blank device, erasure and re-programming of a previously programmed device, or
programming of the Flash memory by the application program in a running system.
21.2 Features
21.3 Applications
The flash boot loader provides both In-System and In-Application programming interfaces
for programming the on-chip flash memory.
21.4 Description
The flash boot loader code is executed every time the part is powered on or reset. The
loader can execute the ISP command handler or the user application code. A a LOW level
after reset at the P0.14 pin is considered as an external hardware request to start the ISP
command handler. Assuming that proper signal is present on X1 pin when the rising edge
on RESET pin is generated, it may take up to 3 ms before P0.14 is sampled and the
decision on whether to continue with user code or ISP handler is made. If P0.14 is
sampled low and the watchdog overflow flag is set, the external hardware request to start
the ISP command handler is ignored. If there is no request for the ISP command handler
execution (P0.14 is sampled HIGH after reset), a search is made for a valid user program.
If a valid user program is found then the execution control is transferred to it. If a valid user
program is not found, the auto-baud routine is invoked.
Pin P0.14 that is used as hardware request for ISP requires special attention. Since P0.14
is in high impedance mode after reset, it is important that the user provides external
hardware (a pull-up resistor or other device) to put the pin in a defined state. Otherwise
unintended entry into ISP mode may occur.
21.4.1 Memory map after any reset
The boot block is 12 kB in size and resides in the top portion (starting from 0x0007 D000)
of the on-chip flash memory. After any reset the entire boot block is also mapped to the
top of the on-chip memory space i.e. the boot block is also visible in the memory region
starting from the address 0x7FFF D000. The flash boot loader is designed to run from this
User manual
UM10139
Chapter 21: Flash Memory System and Programming
Rev. 01 — 15 August 2005
•
In-System Programming: In-System programming (ISP) is programming or
reprogramming the on-chip flash memory, using the boot loader software and a serial
port. This can be done when the part resides in the end-user board.
•
In Application Programming: In-Application (IAP) programming is performing erase
and write operation on the on-chip flash memory, as directed by the end-user
application code.
Rev. 01 — 15 August 2005
User manual
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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