pc87591l-n05 National Semiconductor Corporation, pc87591l-n05 Datasheet - Page 394

• Manufacturer Part Number: pc87591l-n05
• Description: Lpc Mobile Embedded Controller
• Manufacturer: National Semiconductor Corporation

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C.
The PC87591L-N05 Booter program resides in the 4K on-chip ROM.
The Booter has two main functions:
C.1
Header 1 resides at the address 1000
Note: The first eight bytes are not included in the checksum count.
.
• On power-up, it performs all boot procedures and then passes control to the firmware (EC BIOS).
• If there is a problem with the firmware (EC BIOS), or if the user forces Recovery mode, the Booter enters Recovery
• Signature (two bytes at offset 0):
• Bus Width (one word at offset 2):
• Address of Header 2: (1 word at offset 4)
• Action Flag: (1 byte at offset 6)
• Config: (1 byte at offset 7)
mode and allows debugging via JTAG or RS-232 debugging channels.
The signature can be one of the following:
— 49
— 49
This byte instructs the Booter as follows:
The starting address of Header 2. This field stores the PC value of Header 2. Thus, its value is the address divided
by 2. Checksum counting begins at this address.
Reserved.
This byte instructs the Booter as follows:
8-15 Reserved.
0-6 Reserved.
Bit
Bit
7
0
Booter Program
BOOT DATA
16
16
Bus width.
0: External flash device is in 8-bit data mode (byte wide)
1: External flash device is in 16-bit data mode (word wide)
XOR Checksum.
0: Do not perform the XOR checksum
1: Perform the XOR checksum
in the lower byte and 4A
in the lower byte and 4E
16
16
16
in the higher byte or 4A49
in the higher byte or 4E49
in the external flash and is defined as follows:
Offset
00-01
02-03
04-05
06
07
Length
2
2
2
1
1
Description
Description
Address of Header 2
394
Action Flag
Bus Width
Signature
Header 2
16
16
.............
Config
in little endian convention (Light signature),
in little endian convention (Normal signature).
Revision 1.2