Revision 1.26 – October 15, 2007
440EPx – PPC440EPx Embedded Processor
Preliminary Data Sheet
of the external bus, these same pins are used as inputs which are driven by the external master and received by
the EBC in the PPC440EPx. In this example, the pins are also bidirectional, serving both as inputs and outputs.
Multimode Signals
In some cases (for example, Ethernet) the function of a pin may vary with different modes of operation. When a pin
has multiple signal names assigned to distinguish different modes of operation, all of the names are shown.
Strapping Pins
One group of pins is used as strapped inputs during system reset. These pins function as strapped inputs only
during reset and are used for other functions during normal operation (see “Strapping” on page 91). Note that
these are not multiplexed pins since the function of the pins is not programmable.
Unused I/Os
Termination of unused receivers is generally required; however, there are some exceptions that reduce or
eliminate the need for termination.
Signals Multiplexed with GPIO:
By default after reset, signals shared with GPIO pins are configured as GPIO receivers. Termination however,
is not needed if the GPIO during initialization are configured as outputs. To configure as drivers, set and clear
the appropriate bits in the GPIOx_ODR, GPIOx_TCR and GPIOx_OR registers as described in the GPIO
chapter of the user’s manual.
PCI:
When the PCI bridge is unused, configure the PCI controller to park on the bus by pulling the PCIReg0[Gnt}
signal low. Parking forces the PLB3 to PCI bridge to actively drive PCIAD31:0 and PCIC3:0[BE3:0]. The
remaining PCI control signals must be terminated as follows:
– Disable the internal PCI arbiter and enable PCI synchronous mode. (See IIC Boot Strap Chapter in the
user’s manual).
Note: Synchronous mode is not supported when operating the PCI bus. This mode should only be used for
terminating an unused PCI interface).
– Individually connect PCISErr, PCITRDY, and PCIStop through 3kΩ resistors to +3.3V.
– Individually connect PCIReq1:5 through 3kΩ resistors to +3.3V.
– Connect PCIReq0[Gnt] through 1kΩ resistor to GND.
DDR:
– In 32 bit mode, termination is not needed on the upper data, strobe and mask signals when the DDR
I/O and DDR controller are configured for 32 bit mode, SDR0_DDRCFG[64B32B]=0 and
DDR0_14[REDUC]=1.
– Termination of unused ECC signals (ECC0:7, DM8, DQS8) is not needed.
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