CS8900A datasheet(106/128 Pages) CIRRUS

106 / 128 page

106

DS271PP3

CS8900A

Crystal LAN™ ISA Ethernet Controller

CIRRUS LOGIC PRODUCT DATA SHEET

6.0 TEST MODES

6.0.1 Loopback & Collision Diagnostic Tests

Internal and external Loopback and Collision tests

can be used to verify the CS8900A’s functionality

when configured for either 10BASE-T or AUI op-

eration.

6.0.2 Internal Tests

Internal tests allow the major digital functions to be

tested, independent of the analog functions. During

these tests, the Manchester encoder is connected to

the decoder. All digital circuits are operational, and

the transmitter and receiver are disabled.

6.0.3 External Tests

External test modes allow the complete chip to be

tested without connecting it directly to an Ethernet

network.

6.0.4 Loopback Tests

During Loopback tests, the internal Carrier Sense

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

allowing packet reception during packet transmis-

sion.

6.0.5 10BASE-T Loopback and 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 36 de-

scribes these tests.

6.0.6 AUI Loopback and Collision Tests

AUI Loopback and Collision tests are controlled by

two bits in the Test Control register: AUIloop

(Register 19, TestCTL, Bit A) and ENDECloop

(Register 19, TestCTL, Bit 9). Table 37 describes

these tests.

Test Mode

FDX

ENDECloop

Description of Test

10BASE-T Inter-

nal Loopback

Transmit a frame and verify that the frame is received without

error.

10BASE-T Inter-

nal Collision

Transmit frames and verify that collisions are detected and

that the internal counters function properly. After 16 collli-

sions, 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 36. 10BASE-T Loopback and Collision Tests

Test Mode

AUIloop ENDECloop

Description of Test

AUI Internal

Loopback

Transmit a frame and verify that the frame is received without error.

AUI External

Loopback

Connect DO+ to DI+ and DO- to DI-. Transmit a frame and verify

that the frame is received without error (since there is no collision

signal, an SQE error will occur).

AUI Collision

Start transmission and observe DO+/DO- activity. Input a 10 MHz

sine wave to Cl+/Cl- pins and observe collisions.

Table 37. AUI Loopback and Collision Tests

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