EMAC Functional Architecture

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2.7.1Pacing Block

In simple terms, interrupt pacing represents delaying the initial EMAC events to CPU interrupt based on certain criteria. The pacing block is the basic building block for the interrupt pacing operation. One of the motivations for interrupt pacing is that during Ethernet operation, hundreds or thousands of interrupts are generated per second for packets transmitted or received and interrupt pacing relieves the CPU of the burden of processing every single interrupt. This block provides time-based or count-based pacing of interrupts, in any combination. In addition, this block supports reprogramming of timer value and count value without hardware/software race condition and also facilitates use of the same timer and count values for the next event period.

The EVT_IN is the pulse interrupt from EMAC. This is forwarded to timed-delay and divide by N state machines (see Figure 15). The state machine outputs are combined and sent out as EVT_OUT. PS_TICK is the clock tick from the prescalar block. The prescaler block forwards this signal to all the pacing blocks.

PS_TICK

EVT_IN

Figure 15. Pacing Block

Pacing￿block

 

Timed-

EVT_TIMED

delay￿SM

 

DIV NEXT

 

Divide￿SM

EVT_DIV

 

EVT_OUT

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C6472/TCI6486 EMAC/MDIO

SPRUEF8F –March 2006 –Revised November 2010

 

 

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Texas Instruments TMS320TCI6486 manual Pacing Block, Evtout