MEC1322 Datasheet, PDF (258/456 Pages) Microchip Technology – Keyboard and Embedded Controller for Notebook PC

MEC1322
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:
DMA Transfer
TERMINOLOGY
Term
Data Packet
Channel
Device
Master Device
Definition
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.
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.
The Channel is responsible for end-to-end (source-to-destination) Data
Packet delivery.
A Device may refer to a Master or Slave connected to the DMA Channel.
Each DMA Channel may be assigned one or more devices.
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.
Slave Device
Source
Destination
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.
The Slave Device is defined as the device associated with the targeted
Memory Address.
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.
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.
DS00001719D-page 258
 2014 - 2015 Microchip Technology Inc.