About the memory management unit need to know the relevant knowledge

1. How to convert a virtual address to a physical address,
2.MMU of memory access mechanism,
3.tlb,catch and write buffer principles.
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Memory Management Unit The function of the MMU: mapping virtual addresses to physical addresses and providing access to memory.
When the MMU was not activated. CPU cores. All parts, such as Cache,mmu and peripherals, use physical addresses.

After the MMU is started, the CPU cores emit virtual addresses. Converted from MVA to physical address for use by the cache and MMU.

Finally, use the physical address to access the actual device.


Problem:
Why is the conversion from the virtual address to the physical address.






The NAND Flash controller needs to know the relevant knowledge:
1. NAND Flash Chip Interface,
2. Learn how to access NAND flash through the NAND flash controller.
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NAND Flash is the equivalent of a hard disk on a PC that holds the data necessary for the system to execute and can be permanently saved after power-down.
NAND Flash is more used to store data. Smaller size. Longer life. Often use the Yaffs file system, such as Chip k9f1208u0m, Nor Flash for storage programs, often using the JFFS2 file system.
NAND flash controllers are used to simplify the operation of NAND Flash.




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Uart:universal asychronous reciever Transmitter, Universal asynchronous transceiver. The CPU writes parallel data to the UART and the UART sends it serially on a wire. and a wire to receive the data, full duplex mode.


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system clock and timer related knowledge:
1. Understanding the 2440 Clock system
2. How to change the system clock by MPLL
In order to reduce electromagnetic interference. Reduce inter-board cabling requirements, 2440 the external crystal oscillator frequency is usually very low, for example 12MHz, so the PLL needs to improve the system clock.

The ARM920T has 37 registers. Consists of 31 general-purpose registers and 6 program registers.
The ARM system CPU has 7 modes of operation.

The ARM system CPU has the following two working states, namely arm state and thumb state. However, the CPU is in arm state at the same power, so there is no need to worry about CPU working state.

About the memory management unit need to know the relevant knowledge