Transcript
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MPC 555 Memory Controller and Chip
Select
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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
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MPC 555 Memory Controller
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Memory Controller Block Diagram
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Chip Select Based System Design
Device (Keyboard)
CSx
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Chip Select with Peripheral
ACS: Address to CS SetupCSNT: Chip Select Negation Time
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Memory Controller Address Map
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Chip Select Programming
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CS Base Address Register bits
31 V Mapping is valid
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CS Programming: Option Registers
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Option Register bits
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Address Match Logic
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Example Device
Keyboard/Device foo memory map:
0x001f 0000 to 0x00ff ffff
CS1 programmed as: BR1[BA] 0x003e;
OR1[AM] 0x01fe;