Specifications

CDS Daughtercard Architecture

MPC8555E Configurable Development System Reference Manual, Rev. 1

4-8 Freescale Semiconductor

A 22-Ω resistor is selected to match the processor impedance to the PWB impedance, but can be trimmed

or altered as necessary. After daisy-chaining the control signals, the line is extended to a 27-Ω resistor (also

1%) which connects directly to the V

termination plane.

4.4.2 Recommended Part Numbers

For performance and compatibility purposes, only the devices shown in Table 4-2 are guaranteed to work.

Other devices may operate, but architectural issues may affect performance.

4.5 Local Bus Interface

The local bus interface of many processors varies widely, including:

• Direct connections for the Tsi106/Tsi107 family

• 32-bit multiplexed address/data of the MPC85xx family

To accommodate this flexibility, each daughtercard is responsible for presenting an abstract interface to

the carrier board. This interface is designed around a typical Flash/IO-device interface.

For processors which may support high-speed SRAM or SDRAM on their local bus, the daughtercard is

responsible for isolating the high-speed devices from the relatively slower-speed local bus (with respect to

the carrier board). This has the advantage of supporting the flexibility of the processor local bus interface.

It also electrically isolates the high-speed devices from the carrier, which tends to reduce the upper bound

of their operating speed.

In addition to the standard interface signals, an additional set of signals (LB_SIZ(1:0)) are generated on

the daughtercard. These signals indicate the width of the access to the boot flash and other carrier

peripherals. The carrier is responsible for adjusting the local bus interface to those devices, so that they

Table 4-2. CDS DDR SDRAM Compatibility

Manufacturer Size Type Speed Part Number

Samsung 512 MB Unbuff, nonECC DDR400 M368L6523BTM-C(L)CC/C4

M368L6423FTN-C(L)CC

DDR333 M368L6423FTN-C(L)B3

DDR266 M368L6423FTN-C(L)AA

512 MB Unbuff, ECC DDR400 M381L6423FTN-C(L)CC

DDR333 M381L6423FTN-C(L)B3

DDR266 M381L6423FTN-C(L)AA

1 GB Unbuff, nonECC DDR400 M368L2923BTM-C(L)CC/C4

Unbuff, ECC DDR400 M381L2923BTM-C(L)CC/C4

Hynix 512 MB Unbuff, nonECC DDR400 HYMD564646A8J-D43

Unbuff, ECC HYMD564726A8J-D43

1 GB Unbuff, nonECC HYMD512646A8J-D43

Unbuff, ECC HYMD512726A8J-D43