1 MPC 555 Memory Controller and Chip Select. 2 How Does Keyboard Know It’s Memory Map? processor Keyboard Data register 0xf0000000 Control registerR 0xf0000004.

1

MPC 555 Memory Controller and Chip

Select

2

How Does Keyboard Know It’s Memory Map?

processor

Keyboard

Data register 0xf0000000Control register R 0xf0000004

CS Base(0xf0000000)

#Bytes (256) Chip-Select 0 (CS0)

ChipEnable

3

MPC 555 Memory Controller

4

Memory Controller Block Diagram

5

Chip Select Based System Design

Device (Keyboard)

CSx

6

Chip Select with Peripheral

ACS: Address to CS SetupCSNT: Chip Select Negation Time

7

Memory Controller Address Map

8

Chip Select Programming

9

CS Base Address Register bits

31 V Mapping is valid

10

CS Programming: Option Registers

11

Option Register bits

12

Address Match Logic

13

Example Device

Keyboard/Device foo memory map:

0x001f 0000 to 0x00ff ffff

CS1 programmed as: BR1[BA] 0x003e;

OR1[AM] 0x01fe;