8101 datasheet(51/172 Pages) LSI

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10-Bit PHY Interface

2-33

The comma detect output, EN_CDET, is asserted when the receiver in

the 8B10B PCS section has lost word synchronization.Setting the CDET

bit in “Register 9–Conﬁguration 3‚" Section 4.3.10, also asserts

EN_CDET. The EN_CDET output can be used to enable the bit

synchronization process in an external physical layer device.

The controller does not have a pin designated for the standardized

comma detect input, COM_DET, because the receive 8B10B PCS

section has all the necessary logic to acquire word synchronization from

the contents of the receive data stream alone.

2.12.4 Lock To Reference

Setting the LCKREFn bit in “Register 9–Conﬁguration 3‚" Section 4.3.10,

exclusively controls the LCK_REFn output. This output is typically used

to enable the PLL locking process in an external physical layer device.

2.12.5 PHY Loopback

Setting the EWRAP bit in “Register 9–Conﬁguration 3‚" Section 4.3.10,

exclusively controls the EWRAP output. This output is typically used to

enable a loopback function in an external physical layer device.

When the EWRAP pin is asserted, the signal detect input pin, SD, from

an external physical layer device may be in an unknown state. To

counteract this, the SD_EN bit in Register 9 “Conﬁguration 3” should also

be cleared when the EWRAP assert bit is set.

2.12.6 Signal Detect

There is an additional signal detect input pin, SD, which indicates to the

controller that the receive data detected on RXD[9:0] contains valid data.

If SD is asserted, the input data is assumed valid and the receive 8B10B

PCS section is unaffected. If SD is deasserted, the data is assumed to

be invalid and the receive 8B10B PCS section is forced into the loss of

sync state. Although SD is not part of the IEEE-deﬁned 10-bit PHY

interface, it is typically sourced from an external physical layer device.

The controller powers up with the SD pin disabled (SD has no affect on

the receive word synchronization state machine). To enable the SD pin,

the SD_EN bit must be set in “Register 9–Conﬁguration 3‚"

Section 4.3.10.

8101 Datasheet(PDF) 51 Page - LSI Computer Systems