CS89712 datasheet(138/170 Pages) CIRRUS

138 / 170 page

CS89712

138

DS502PP2

4.1.6

Loopback/Collision Diagnostic Tests

Internal and external Loopback and Collision tests

can be used to verify the CS89712’s Ethernet port

functionality. Internal tests allow the major digital

functions to be tested, independent of the analog

functions. During these tests, the Manchester en-

coder is connected to the decoder. All digital cir-

cuits are operational, and the transmitter and

receiver are disabled. External test modes allow the

complete chip to be tested without connecting it di-

rectly to an Ethernet network.

4.1.7

Loopback Tests

During Loopback tests, the internal Carrier Sense

(CRS) signal, used to detect collisions, is ignored,

allowing packet reception during transmission.

4.1.8

10BASE-T Loopback/Collision Tests

10BASE-T Loopback and Collision Tests are con-

trolled by two bits in the Test Control register:

FDX (Register 19, TestCTL, Bit E) and ENDE-

Cloop (Register 19, TestCTL, Bit 9). Table 88 de-

scribes these tests.

4.2 In-Circuit Emulation

4.2.1

Introduction

EmbeddedICE

™ is an extension to the architecture

of the ARM family of processors, and provides the

ability to debug cores that are deeply embedded

into systems. It consists of three parts:

1) A set of extensions to the ARM core

2) The EmbeddedICE macrocell, which provides

external access to the extensions

Test Mode

FDX

ENDECloop

DisableLT

Description of Test

10BASE-T Internal

Loopback

Transmit a frame and verify that the frame is

received without error.

10BASE-T Internal

Collision

Transmit frames and verify that collisions are

detected and that the internal counters function

properly. After 16 collisions, verify that 16coll

(Register 8, TxEvent, Bit F) is set.

10BASE-T

External Loop-

back

Connect TXD+ to RXD+ and TXD- to RXD-.

Transmit a frame and verify that the frame is

received without error.

10BASE-T

External Collision

Connect TXD+ to RXD+ and TXD- to RXD-.

Transmit frames and verify that collisions are

detected and that internal counters function

properly. After 16 collisions, verify that 16coll

(Register 8, TxEvent, Bit F) is set.

Table 88. 10BASE-T Loopback and Collision Tests

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