PXS20RM Datasheet, PDF (149/1368 Pages) Freescale Semiconductor, Inc – PXS20 Microcontroller

SSCM.
STATUS.
PUB
=0
Comparison with
0xFEEDFACE
=1
CAFEBEEF
SSCM.
STATUS.
SEC
=0
=1
Compare password
by hardware
Comparison with
password saved in
NVPWD
Boot Assist Module (BAM)
Wait
Verify if flash
is unsecured
Figure 8-3. Password check flow
8.4.2.6 Download start address, VLE bit and code size
The next 8 bytes received by the MCU contain a 32-bit Start Address, the VLE mode bit and a 31-bit code
Length as shown in Figure 8-4.
The VLE bit (Variable Length Instruction) is used to indicate for which instruction set the code has been
compiled. The BAM supports the download of VLE code (VLE bit = 1) and Power Architecture
Technology (VLE bit = 0). In case of Power Architecture Technology, the MMU page for the RAM space
(0x4000_0000 - 0x7FFF_FFFF) will be modified to select Power Architecture. Otherwise the MMU page
for this page will continue to select VLE code.
NOTE
Power Architecture Technology is supported in cut2 and beyond only
The Start Address defines where the received data will be stored and where the MCU will branch after the
download is finished. The two LSB bits of the Start Address are ignored by the BAM program, such that
the loaded code should be 32-bit word aligned.
The Length defines how many data bytes have to be loaded.
PXS20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor
8-7