Boot Assist Module (BAM)
9-16
Freescale Semiconductor
PXR40 Microcontroller Reference Manual, Rev. 1
9.5.6
Booting from the Development Bus
If the MCU boots in one of the Development Bus boot modes, the BAM program:
•
Reprograms the MMU entries for EBI and internal flash (see
)
•
Sets up the EBI and development bus pins
•
Tries to read RCHW from logical address 0x2000_0000
If the valid RCHW is read from that address, the BAM program:
•
Reads the user application code start address from 0x2000_0004 address
•
Parses RCHW
•
Sets up watchdogs
•
Updates EBI, SRAM and internal flash MMU entries(1-3), according to RCHW[VLE]
•
Passes control to the user code
If no valid RCHW was read, BAM switches to the serial boot mode.
9.5.6.1
EBI Configuration for Separate Address and Data Development Bus
Boot Mode
The BAM program sets up EBI related registers as shown in the
RCHW[PS0] must be programmed to “1”, since the development bus does not support 32-bit port size in
that sub-mode.
Table 9-11. MMU Configuration for Development Bus Boot modes
TLB
Entry
Region
Logical
Base Address
Physical
Base Address
Size
Attributes
1
Internal Flash
0x0000_0000
0x2000_0000
16 MB
Not guarded
Big endian
Global PID
2
EBI
0x2000_0000
0x2000_0000
16 MB
Not guarded
Big endian
Global PID
Table 9-12. Development Bus/EBI Register Settings for Separate Address Data lines mode
Register
Function
Value
Comments
EBI_CAL_BR0
—
0x2000_0803
Sets the base address to 0x2000_0000,16-bit wide
bus, burst Inhibit
EBI_CAL_OR0
—
0xFF80_00F0
Set 15 wait states, 8MB
SIU_PCR259–
SIU_PCR293
D_ADD[12:30],
D_ADD_DAT[0:15]
0x0440
Set pads to 20pf drive strength
SIU_PCR305–
SIU_PCR307
D_ADD[9:11]
SIU_PCR256
D_CS0
0x443
Set pads to 20pf drive strength and pull-up enable
SIU_PCR295
D_WE0
SIU_PCR297
D_OE
SIU_PCR298
D_TS
Summary of Contents for PXR4030
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