p89lpc9402 NXP Semiconductors, p89lpc9402 Datasheet - Page 43

• Manufacturer Part Number: p89lpc9402
• Description: 8-bit Microcontroller With Accelerated Two-clock 80c51 Core 8 Kb 3 V Byte-erasable ?ash With 32 Segment 4 Lcd Driver
• Manufacturer: NXP Semiconductors

NXP Semiconductors
P89LPC9402_1
Product data sheet
7.28.10 Hardware activation of the bootloader
7.28.9 Power-on reset code execution
7.29 User configuration bytes
7.30 User sector security bytes
in components and circuit board area. The ISP function uses five pins (V
RXD, and RST). Only a small connector needs to be available to interface your application
to an external circuit in order to use this feature.
The P89LPC9402 contains two special flash elements: the Boot Vector and the Boot
Status bit. Following reset, the P89LPC9402 examines the contents of the Boot Status bit.
If the Boot Status bit is set to zero, power-up execution starts at location 0000H, which is
the normal start address of the user’s application code. When the Boot Status bit is set to
a value other than zero, the contents of the Boot Vector are used as the high byte of the
execution address and the low byte is set to 00H.
Table 10
factory-provided bootloader is pre-programmed into the address space indicated and
uses the indicated bootloader entry point to perform ISP functions. This code can be
erased by the user.
Remark: Users who wish to use this loader should take precautions to avoid erasing the
1 kB sector that contains this bootloader. Instead, the page erase function can be used to
erase the first eight 64-byte pages located in this sector.
A custom bootloader can be written with the Boot Vector set to the custom bootloader, if
desired.
Table 10.
The bootloader can also be executed by forcing the device into ISP mode during a
power-on sequence (see the P89LPC9402 User manual for specific information). This has
the same effect as having a non-zero status byte. This allows an application to be built that
will normally execute user code but can be manually forced into ISP operation. If the
factory default setting for the Boot Vector (1FH) is changed, it will no longer point to the
factory preprogrammed ISP bootloader code. After programming the flash, the status byte
should be programmed to zero in order to allow execution of the user’s application code
beginning at address 0000H.
Some user-configurable features of the P89LPC9402 must be defined at power-up and
therefore cannot be set by the program after start of execution. These features are
configured through the use of the flash byte UCFG1 and UCFG2. Please see the
P89LPC9402 User Manual for additional details.
There are eight User Sector Security Bytes on the P89LPC9402 device. Each byte
corresponds to one sector. Please see the P89LPC9402 User manual for additional
details.
Device
P89LPC9402
shows the factory default Boot Vector setting for these devices. A
Default Boot Vector values and ISP entry points
Default
Boot Vector
1FH
Rev. 01 — 22 April 2009
8-bit microcontroller with accelerated two-clock 80C51 core
Default
boot loader
entry point
1F00H
Default boot loader
code range
1E00H to 1FFFH
P89LPC9402
© NXP B.V. 2009. All rights reserved.
1 kB sector
range
1C00H to 1FFFH
DD
, V
SS
, TXD,
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