Motorola MSC8101 ADS User's Guide download pdf (Page 77)

MSC8101 User’s Guide 4-1

Chapter 4

Connecting External Memories and

Memory-Mapped Devices

This chapter illustrates several memory interconnection options for the MSC8101 bus and

memory controller. It outlines the hardware connections and memory register settings for

the MSC8101 when the PowerPC system bus connects to EPROM, Flash memory,

Synchronous DRAM (SDRAM), or an MSC8101 HDI16 slave.

4.1 Memory Controller Basics

The MSC8101 has three integrated memory controllers tailored to suit a variety of bus

control profiles. This chapter discusses all of these memory controllers and illustrates

them with examples:

■ General-purpose chip-select machine (GPCM). A baseline controller for simple

non-multiplexed interfaces such as EPROM, Flash memory, and SRAM. A

GPCM-derived chip select interfaces simple, non-bursting devices over a selection

of port sizes (8-, 16-, 32- and 64-bit) and a wide range of speed grades. To illustrate

its use, the timing of a Flash EPROM interface example is discussed.

■ Dedicated SDRAM controller. Gluelessly connects to a variety of

JEDEC-compatible SDRAMs of varying size and number of banks. The SDRAM

controller generates the row address strobe (

RAS), column address strobe (CAS), chip

select (

CS), and control signal combinations. The programmable address

multiplexing and timing characteristics enable you to control the size of the

SDRAM, row to column address latch timing, page-mode burst operation, and

bank interleaving. To illustrate SDRAM controller operation, this chapter discusses

the interface to a 100-125 MHz SDRAM on the 100 MHz Bus.

■ User-programmable machine (UPM). A flexible alternative controller by which

users can define a fully programmable bus cycle profile for a range of such

standard or proprietary interfaces as SRAM, EDO DRAM, and ASICs. The UPM

offers much more flexibility in timing to target a broader range of system devices

than the GPCM. Through the UPM-controlled interface, software can define the

chip selects and control strobes on each bus clock to a one quarter of one clock

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Motorola MSC8101 ADS User's Guide Page 77