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EMAC Port Registers

5.40 Transmit Pacing Algorithm Test Register (TPACETEST)

The Transmit Pacing Algorithm Test Register (TPACETEST) is shown in Figure 68 and described in Table 68.

Figure 68. Transmit Pacing Algorithm Test Register (TPACETEST)

31

 

 

16

 

Reserved

 

 

 

R-0

 

 

15

5

4

0

Reserved

 

 

PACEVAL

R-0

 

 

R-0

LEGEND: R = Read only; -n= value after reset

Table 68. Transmit Pacing Algorithm Test Register (TPACETEST) Field Descriptions

Bit

Field

Value

Description

31-5

Reserved

0

Reserved

4-0

PACEVAL

 

Pacing register current value. A nonzero value in this field indicates that transmit pacing is active. A

 

 

 

transmit frame collision or deferral causes PACEVAL to be loaded with 1Fh (31); good frame

 

 

 

transmissions (with no collisions or deferrals) cause PACEVAL to be decremented down to 0.

 

 

 

When PACEVAL is nonzero, the transmitter delays four Inter Packet Gaps between new frame

 

 

 

transmissions after each successfully transmitted frame that had no deferrals or collisions. If a

 

 

 

transmit frame is deferred or suffers a collision, the IPG time is not stretched to four times the

 

 

 

normal value. Transmit pacing helps reduce capture effects, which improves overall network

 

 

 

bandwidth.

126

Ethernet Media Access Controller (EMAC)/Management Data Input/Output (MDIO)

SPRU975B –August 2006

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Texas Instruments TMS320C645x DSP manual Transmit Pacing Algorithm Test Register Tpacetest, Paceval