Revision 1.21 – June 22, 2012
PPC440GX Embedded Processor
Initialization
Data Sheet
The PPC440GX provides the option for setting initial parameters based on default values or by reading them from
a slave PROM attached to the IIC0 bus (see “Serial EEPROM” below). Some of the default values can be altered
by strapping on 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 PPC440GX 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) (recommended value is 3kΩ to
3.3V) or pull-down (logical 0) (recommended value is 1 kΩ to GND) resistors to select the desired default
conditions. They are used for strap functions only during reset. Following reset they are used for normal functions.
The following table lists the strapping pins along with their functions and strapping options:
Table 21. Strapping Pin Assignments
Ball Strapping
Function
Option
V24
V02
L07
(UART0_DCD)
(UART0_DSR)
(GMC1TxEr)
Serial device is disabled. Each of the four options (A–
D) is a combination of boot source, boot-source width,
and clock frequency specifications. Refer to the IIC
Bootstrap Controller chapter in the PPC440GX
Embedded Processor User’s Manual for details.
A
B
0
0
0
1
1
1
0
x
1
0
0
1
0
1
0
0
1
1
C
D
Serial device is enabled. The option being selected is
the IIC0 slave address that will respond with strapping
data.
0x54
0x50
Serial EEPROM
During reset, initial conditions other than those obtained from the strapping pins can be read from a ROM device
connected to the IIC0 port. At the de-assertion of SysReset, if the bootstrap controller is enabled, the PPC440GX
sequentially reads 16 bytes from the ROM device on the IIC0 port and sets the SDR0_SDSTP0, SDR0_SDSTP1,
SDR0_SDSTP2, and SDR0_SDSTP3 registers accordingly.
The initialization settings and their default values are covered in detail in the PowerPC 440GX Embedded
Processor User’s Manual.
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AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
