MEC1322 datasheet(258/456 Pages) MICROCHIP

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MEC1322

DS00001719D-page 258

 2014 - 2015 Microchip Technology Inc.

21.0 INTERNAL DMA CONTROLLER

21.1

Introduction

The Internal DMA Controller transfers data to/from the source from/to the destination. The firmware is responsible for

setting up each channel. Afterwards either the firmware or the hardware may perform the flow control. The hardware

flow control exists entirely inside the source device. Each transfer may be 1, 2, or 4 bytes in size, so long as the device

supports a transfer of that size. Every device must be on the internal 32-bit address space.

21.2

References

No references have been cited for this chapter

21.3

Terminology

TABLE 21-1:

TERMINOLOGY

Term

Definition

DMA Transfer

This is a complete DMA Transfer which is done after the Master Device

terminates the transfer, the Firmware Aborts the transfer or the DMA

reaches its transfer limit.

A DMA Transfer may consist of one or more data packets.

Data Packet

Each data packet may be composed of 1, 2, or 4 bytes. The size of the data

packet is limited by the max size supported by both the source and the des-

tination. Both source and destination will transfer the same number of bytes

per packet.

Channel

The Channel is responsible for end-to-end (source-to-destination) Data

Packet delivery.

Device

A Device may refer to a Master or Slave connected to the DMA Channel.

Each DMA Channel may be assigned one or more devices.

Master Device

This is the master of the DMA, which determines when it is active.

The Firmware is the master while operating in Firmware Flow Control.

The Hardware is the master while operating in Hardware Flow Control.

The Master Device in Hardware Mode is selected by DMA Channel Con-

trol:Hardware Flow Control Device

. It is the index of the Flow Control

Port.

Slave Device

The Slave Device is defined as the device associated with the targeted

Memory Address.

Source

The DMA Controller moves data from the Source to the Destination. The

Source provides the data. The Source may be either the Master or Slave

Controller.

Destination

The DMA Controller moves data from the Source to the Destination. The

Destination receives the data. The Destination may be either the Master or

Slave Controller.

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