8101 datasheet(76/172 Pages) LSI

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2-58

Functional Description

2.19.3 Counter Rollover

Counters normally roll over to zero when they exceed their maximum

count, (receive an increment when counter is at maximum count). The

counters can be programmed to freeze and stop counting once they

reach their maximum count. Setting the CTR_ROLL bit in “Register 9–

Conﬁguration 3‚" Section 4.3.10, programs the counters to freeze when

they reach their maximum count.

2.19.4 Counter Maximum Packet Size

The maximum packet size used for the management counter statistics

can be programmed to be one of four values. Setting the CMXPKT[1:0]

bits in “Register 10–Conﬁguration 4‚" Section 4.3.11, select the maximum

packet size. This selection is described in the register descriptions for

those registers and is also summarized in Table 2.15.

The bits in Table 2.15 affect the maximum packet size for the counters

only; the maximum packet size for the MAC section is described in

Section 2.8, “Receive MAC”.

2.19.5 Counter Reset

Setting the CTRRST bit in “Register 7–Conﬁguration 1‚" Section 4.3.8,

resets all counters to zero. Asserting the controller reset pin, RESETn,

also resets the counters to zero.

Table 2.15

Counter Maximum Packet Size Selection

CMXPKT [1:0]

Maximum Packet Size (bytes)

Unlimited

1535

1522

1518

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