V62SLASH12615-01XE-R datasheet(37/98 Pages) TI1

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VCC

AN0 = 1

AN1 = 1

AN_EN = 1

DP83848-EP

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SLLSEC6E – SEPTEMBER 2012 – REVISED JUNE 2019

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Detailed Description

Figure 5-1. AN Strapping and LED Loading Example

5.3.3.2

LED Direct Control

The DP83848-EP provides another option to directly control any or all LED outputs through the LED direct

control register (LEDCR), address 18h. The register does not provide read access to LEDs.

5.3.4

Internal Loopback

The DP83848-EP includes a Loopback Test mode for facilitating system diagnostics. The Loopback mode

is selected through bit 14 (Loopback) of the Basic Mode Control Register (BMCR). Writing 1 to this bit

enables MII transmit data to be routed to the MII receive outputs. Loopback status may be checked in bit 3

of the PHY Status Register (PHYSTS). While in Loopback mode the data will not be transmitted onto the

media. To ensure that the desired operating mode is maintained, Auto-Negotiation should be disabled

before selecting the Loopback mode.

5.3.5

BIST

The DP83848-EP incorporates an internal Built-in Self Test (BIST) circuit to accommodate in-circuit testing

or diagnostics. The BIST circuit can be used to test the integrity of the transmit and receive data paths.

BIST testing can be performed with the part in the internal loopback mode or externally looped back using

a loopback cable fixture.

The BIST is implemented with independent transmit and receive paths, with the transmit block generating

a continuous stream of a pseudo random sequence. The user can select a 9 bit or 15 bit pseudo random

sequence from the PSR_15 bit in the PHY Control Register (PHYCR). The received data is compared to

the generated pseudo-random data by the BIST Linear Feedback Shift Register (LFSR) to determine the

BIST pass/fail status.

The pass/fail status of the BIST is stored in the BIST status bit in the PHYCR register. The status bit

defaults to 0 (BIST fail) and will transition on a successful comparison. If an error (mis-compare) occurs,

the status bit is latched and is cleared upon a subsequent write to the Start/Stop bit.

For transmit VOD testing, the Packet BIST Continuous Mode can be used to allow continuous data

transmission, setting BIST_CONT_MODE, bit 5, of CDCTRL1 (0x1Bh).

The number of BIST errors can be monitored through the BIST Error Count in the CDCTRL1 (0x1Bh), bits

[15:8].

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