Revision 1.23 - Sept 26, 2006
Data Sheet
PowerPC 440SP Embedded Processor
Initialization
The PPC440SP provides an option for setting initial parameters based on default values or by reading them from a
serial “bootstrap” ROM attached to the IIC0 bus. These options are defined by strapping on three external pins
(see “Strapping” below).
Strapping
While the SysReset input pin is low (system reset), the state of certain I/O pins is read to enable certain default
initial conditions prior to PPC440SP start-up. The actual capture instant is the nearest SysClk edge before the
deassertion of reset. These pins must be strapped using external pull-up (logical 1) or pull-down (logical 0)
resistors to select the desired default conditions. They are used for strap functions only during reset. Following
reset they are used for normal functions.
Figure 21 lists the strapping pins along with their functions and strapping options:
Table 21. Strapping Pin Assignments
Pin Strapping
Bit 1
Bit2
Function
Option
Bit 0
A08
(UART0_DCD)
C11
(UART0_DSR)
C09
(UART0_CTS)
Serial Bootstrap ROM is disabled (Bit 0 off).
Refer to the IIC Bootstrap Controller chapter in the
PPC440SP Embedded Processor User’s Manual
for details.
Boot from EBC
Boot from PCI
0x54
0
0
1
1
1
1
0
1
0
1
0
1
Serial Bootstrap ROM is enabled (Bit 0 on).
The options being selected are the IIC0 slave
address that responds with strapping data and
reading 128 bits from the Bootstrap ROM.
0
0
1
1
0x50
Serial Bootstrap ROM is enabled (Bit 0 on).
The options being selected are the IIC0 slave
address that responds with strapping data and
reading 256 bits from the Bootstrap ROM.
0x54
0x50
Serial Bootstrap ROM
During reset, if the serial device is enabled, initial conditions can be read from a ROM connected to the IIC0 port. In
this case, at the de-assertion of SysReset, the PPC440SP sequentially reads up to 32 bytes from the ROM device
on the IIC0 port and sets the SDR0_SDSTP0 - SDR0_SDSTP7 registers accordingly.
The initialization settings and their default values are described in detail in the PPC440SP Embedded Processor
User’s Manual.
AMCC Proprietary
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AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
