CS8900-CQ3 Cirrus Logic, CS8900-CQ3 Datasheet - Page 69

• Manufacturer Part Number: CS8900-CQ3
• Description: Crystal LAN ISA Ethernet Controller
• Manufacturer: Cirrus Logic

DS271PP3
4.4.22 Register 19: Test Control
(TestCTL, Read/Write, Address: PacketPage base + 0118h)
TestCTL controls the diagnostic test modes of the CS8900A.
011001
DisableLT
ENDECloop
AUIloop
Disable Backoff
FDX
At reset, if no EEPROM is found by the CS8900A, then the register has the following initial state. If an EEPROM is
found, then the register’s initial value may be set by the EEPROM. See Section 3.3 on page 19.
Reset value is: 0000 0000 0001 1001
CS8900A
Crystal LAN™ ISA Ethernet Controller
DisableLT
F
7
FDX
Register.
link status. DisableLT is used in conjunction with the LinkOK (Register 14, LineST, Bit 7) as fol-
lows:
LinkOK
output is connected to the decoder input. The 10BASE-T and AUI transmitters and receivers
are disabled. When clear, the CS8900A is configured for normal operation.
the AUI. When clear, the CS8900A is configured for normal AUI operation.
of the inter packet gap before starting transmission. When clear, the backoff algorithm is used.
nored. This bit must be set when performing loopback tests on the 10BASE-T port. When clear,
the CS8900A is configured for standard half-duplex 10BASE-T operation.
These bits provide an internal address used by the CS8900A to identify this as the Test Control
When set, the 10BASE-T interface allows packet transmission and reception regardless of the
When set, the CS8900A enters internal loopback mode where the internal Manchester encoder
When set, the CS8900A allows reception while transmitting. This facilitates loopback tests for
When set, the backoff algorithm is disabled. The CS8900A transmitter looks only for completion
When set, 10BASE-T full duplex mode is enabled and CRS (Register 14, LineST, Bit E) is ig-
E
6
0
0
1
D
5
DisableLT
CIRRUS LOGIC PRODUCT DATA SHEET
1
N/A
0
C
4
DisableLT overrides LinkOK to allow packet
transmission and reception. Transmitter
does not send link pulses.
Disable has no meaning if LinkOK = 1.
No packet transmission for reception
allowed. Transmitter sends link impulses.
Disable Back-
off
B
3
011001
AUIloop
A
2
ENDEC loop
1
9
0
8
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