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1.3
CPU Vector Table
Math tables
and functions
Bootloader
functions
Reset vector
CPU vector table
64 x 16
0x3F F000
0x3F FB50
0x3F FFFF
0x3F FFC0
Reset fetched from here when
VMAP=1
Other vectors fetched from here when
VMAP=1, ENPIE=0
CPU Vector Table
A CPU vector table resides in boot ROM memory from address 0x3F FFC0 - 0x3F FFFF. This vector table
is active after reset when VMAP = 1, ENPIE = 0 (PIE vector table disabled).
Figure 1-2. Vector Table Map
A
The VMAP bit is located in Status Register 1 (ST1). VMAP is always 1 on reset. It can be changed after reset by
software, however the normal operating mode will be to leave VMAP = 1.
B
The ENPIE bit is located in the PIECTRL register. The default state of this bit at reset is 0, which disables the
Peripheral Interrupt Expansion block (PIE).
The only vector that will normally be handled from the internal boot ROM memory is the reset vector
located at 0x3F FFC0. The reset vector is factory programmed to point to the InitBoot function stored in
the boot ROM. This function starts the boot load process. A series of checking operations is performed on
General Purpose I/O (GPIO I/O) pins to determine which boot mode to use. This boot mode selection is
described in
of this document.
The remaining vectors in the boot ROM are not used during normal operation. After the boot process is
complete, you should initialize the Peripheral Interrupt Expansion (PIE) vector table and enable the PIE
block. From that point on, all vectors, except reset, will be fetched from the PIE module and not the CPU
vector table shown in
14
Boot ROM Overview
SPRU722C – November 2004 – Revised October 2006