NXP Semiconductors MPC5644A, Reference Manual, Page: 101 / 1735

Resets
MPC5644A Microcontroller Reference Manual, Rev. 6
Freescale Semiconductor 101
4.7 Reset configuration
4.7.1 Reset configuration half word (RCHW)
4.7.1.1 RCHW overview
The Reset Configuration Half Word (RCHW) defines boot options and must be programmed in a choice
of predefined locations in internal flash. The word at the word address boundary after the RCHW must be
programmed with the user application’s starting address. The BAM passes control to the user application
at this starting address.
On every reset except the Software External Reset (SER), in internal or external boot modes, the BAM
attempts to read the RCHW from internal or external memory respectively. The locations for the RCHW
are given in
Table 4-4 . For internal boot, the predefined locations are searched in the order given in the
table. If a valid RCHW is not found in internal boot mode or in external boot mode, the BAM initiates the
serial boot mode. Note that in serial boot mode, a user defined start address must still be supplied as part
of the download protocol. Refer to the BAM Chapter for complete details.
4.7.1.2 RCHW structure
When booting from the external flash device, the RCHW must reside in the first 16 bits of memory.
Table 4-4. RCHW location
Boot mode Address
External 0x0000_0000
Internal 0x0000_0000
0x0000_4000
0x0001_0000
0x0001_C000
0x0002_0000
0x0003_0000
BOOT_BLOCK_A 0x0000_0000
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
SWT WTE PS0 VLE 0 1 0 1 1 0 1 0
Boot Identifier = 0x5A
Figure 4-3. Reset Configuration Half Word