Texas Instruments TMS320DM646x manual Emac Module Components, Receive DMA Engine, Receive Fifo

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Architecture

2.8EMAC Module

This section discusses the architecture and basic function of the EMAC module.

2.8.1EMAC Module Components

The EMAC module (Figure 11) interfaces to the outside world through the Media Independent Interface (MII) and interfaces to the system core through the EMAC control module. The EMAC consists of the following logical components:

∙The receive path includes: receive DMA engine, receive FIFO, and MAC receiver

∙The transmit path includes: transmit DMA engine, transmit FIFO, and MAC transmitter

∙Statistics logic

∙State RAM

∙Interrupt controller

∙Control registers and logic

∙Clock and reset logic

Figure 11. EMAC Module Block Diagram

Configuration bus	Clock and
	reset logic
	Receive	Receive	MAC
	DMA engine	FIFO	receiver
EMAC	Interrupt	State		SYNC
control			Statistics
	controller	RAM
module
	Transmit	Transmit	MAC
	DMA engine	FIFO	transmitter
Configuration bus	Control
	registers

2.8.1.1Receive DMA Engine

The receive DMA engine is the interface between the receive FIFO and the system core. It interfaces to the CPU through the bus arbiter in the EMAC control module. This DMA engine is totally independent of the device DMA.

2.8.1.2Receive FIFO

The receive FIFO consists of 68 cells of 64 bytes each and associated control logic. The FIFO buffers receive data in preparation for writing into packet buffers in device memory, and also enable receive FIFO flow control.

38 Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO) SPRUEQ6–December 2007

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