Motorola MC68HC908JB8, Reference Manual

Page: 47 / 244

Software Module Descriptions
How to Build the Compiler Project
USB08 Evaluation Board Designer Reference Manual
MOTOROLA Software Module Descriptions 47
In the linker file:
• The starting addresses of the various segments are set.
• The text segment starts at the address 0xDC00 (for example, at
the beginning of the internal FLASH memory).
• The constants immediately follow the text segment.
• The zero page starts at 0x0040 instead of the usual 0x0000.
• The MC68HC908JB8 control registers are located in the address
range 0x0000–0x0040.
• The data segment follows the zero page in the random-access
memory (RAM).
• The interrupt vectors start at 0xFFF0 and the stack pointer is set
to 0x013F (end of the internal RAM memory).
Table 3-1 shows the approximate values for memory utilization when
USB communication has been implemented.
Table 3-1. Memory Utilization
Starting
Address
End
Address
Length Contents
0x0000 0x003F 64 byte MC68HC908JB8 control registers
0x0040 0x0075 53 byte Variables in RAM
0x0076 0x0117 163 byte Free RAM
0x0118 0x013F 40 byte Stack in RAM
0xDC00 0xE2FF 1.8 Kbyte Code and constant values
0xE300 0xFBFF 6.2 Kbyte Free FLASH memory
0xFFF0 0xFFFF 16 byte Interrupt and reset vectors