MPC8540 datasheet(817/1302 Pages) FREESCALE

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Functional Description

MPC8540 PowerQUICC III Integrated Host Processor Reference Manual, Rev. 1

Freescale Semiconductor

15-39

Figure 15-24 describes the DMA transaction flow.

Figure 15-24. DMA Transaction Flow with DMA Descriptors

Current list descriptor Address Register

List Descriptor

Link Descriptor

Link Descriptor (EOLND)

List Descriptor

Descriptors In Memory

DMA Controller Flow (Extended Mode)

MRn[CS] is set by software after programming

Start

Finish

Fetch the first list descriptor using the CLSDARn address.

Write NLSDARn, CLNDARn.

Fetch the first link descriptor.

Write programming model registers.

Begin DMA transfer using SARn, SATRn, DARn, DATRn.

After transfer check if NLNDARn[EOLND] is set.

Move NLNDARn to CLNDARn.

Fetch the current link descriptor.

Write programming model registers.

Begin DMA transfer using SARn, SATRn, DARn, DATRn.

After DMA transfer check if NLNDARn[EOLND] is set.

Check if NLSDARn[EOLSD] is set.

Move NLSDARn to CLSDARn.

Fetch the current list descriptor.

Write NLSDARn, CLNDARn.

Move NLNDARn to CLNDARn.

Fetch the first link descriptor.

Write programming model registers.

Begin DMA transfer using SARn, SATRn, DARn, DATRn.

After DMA transfer check if NLNDARn[EOLND] is set.

Move NLNDARn to CLNDARn.

Fetch the current link descriptor.

Write programming model registers.

Begin DMA transfer using SARn, SATRn, DARn, DATRn.

After DMA transfer check if NLNDARn[EOLND] is set.

Check if NLSDARn[EOLSD] is set.

Move NLSDARn to CLSDARn.

Fetch the current list descriptor.

Write NLSDARn, CLNDARn.

Fetch the first link descriptor.

Write programming model registers.

Begin DMA transfer using SARn, SATRn, DARn, DATRn.

After DMA transfer check if NLNDARn[EOLND] is set.

Move NLNDARn to CLNDARn.

Fetch the current link descriptor.

Write programming model registers.

Begin DMA transfer using SARn, SATRn, DARn, DATRn.

After DMA transfer check if NLNDARn[EOLND] is set.

Check if NLSDARn[EOLSD] is set.

Clear SRn[CB].

DMA Transfer Complete

Link Descriptor

Link Descriptor (EOLND)

List Descriptor

Link Descriptor

Link Descriptor (EOLND/EOLSD)

descriptors in memory.

MPC8540 Datasheet(PDF) 817 Page - Freescale Semiconductor, Inc

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