Microcontroller User's Manual
MOTOROLA Chapter 2. ColdFire Core 2-11
Exception Processing Overview
Third, the processor saves the current context by creating an exception stack frame on the
supervisor system stack. As a result, the exception stack frame is created at a 0-modulo-4
address on the top of the current system stack. Additionally, the processor uses a simplified
fixed-length stack frame for all exceptions. The exception type determines whether the
program counter placed in the exception stack frame defines the location of the faulting
instruction (fault) or the address of the next instruction to be executed (next).
Fourth, the processor calculates the address of the first instruction of the exception handler.
By definition, the exception vector table is aligned on a 1 Mbyte boundary. This instruction
address is generated by fetching an exception vector from the table located at the address
defined in the vector base register. The index into the exception table is calculated as (4 x
vector number). Once the exception vector has been fetched, the contents of the vector
determine the address of the first instruction of the desired handler. After the instruction
fetch for the first opcode of the handler has been initiated, exception processing terminates
and normal instruction processing continues in the handler.
All ColdFire processors support a 1024-byte vector table aligned on any 1 Mbyte address
boundary (see Table 2-5). The table contains 256 exception vectors; the first 64 are defined
by Motorola and the remaining 192 are user-defined interrupt vectors.
Table 2-5. Exception Vector Assignments
Vector
Number(S)
Vector
Offset (Hex)
Stacked
Program
Counter
Assignment
0 0x000 — Initial stack pointer
1 0x004 — Initial program counter
2 0x008 Fault Access error
3 0x00C Fault Address error
4 0x010 Fault Illegal instruction
5 0x014 Fault Divide by zero
6–7 0x018–0x01C — Reserved
8 0x020 Fault Privilege violation
9 0x024 Next Trace
10 0x028 Fault Unimplemented line-a opcode
11 0x02C Fault Unimplemented line-f opcode
12 0x030 Next Debug interrupt
13 0x034 — Reserved
14 0x038 Fault Format error
15–23 0x03C–0x05C — Reserved
24 0x060 Next Spurious interrupt
25–31 0x064-0x07C — Reserved
32–47 0x080–0x0BC Next Trap # 0-15 instructions
48–63 0x0C0–0x0FC — Reserved