XC2200 Derivatives
System Units (Vol. 1 of 2)
Interrupt and Trap Functions
User’s Manual
5-48
V2.1, 2008-08
ICU_X2K, V2.2
Memory Access Error (B)
When a memory access error is detected, the ACER flag is set in register TFR and the
CPU enters the access error trap routine. The access error is reported in the following
cases:
•
access to Flash memory while it is disabled
•
access to Flash memory from outside while read-protection is active
•
double bit error detected when reading Flash memory
•
access to reserved locations (see memory map in
•
parity error during an access to RAM
In case of an access error, additionally the soft-trap code 1E9B
H
is issued.
Protection Fault Trap (B)
Whenever one of the special protected instructions is executed where the opcode of that
instruction is not repeated twice in the second word of the instruction and the byte
following the opcode is not the complement of the opcode, the PRTFLT flag in register
TFR is set and the CPU enters the protection fault trap routine. The protected
instructions include DISWDT, EINIT, IDLE, PWRDN, SRST, ENWDT and SRVWDT.
The instruction that causes the protection fault trap is executed like a NOP.
Illegal Word Operand Access Trap (B)
Whenever a word operand read or write access is attempted to an odd byte address, the
ILLOPA flag in register TFR is set and the CPU enters the illegal word operand access
trap routine.