Force SYS68K/CPU-30 R4, Техническое справочное руководство

Страница: 103 / 209

Hardware Description SYS68K/CPU-30 R4 Technical Reference Manual
Page 90
3.13.2.2 The LANCE
Interrupt
The LANCE is able to interrupt the CPU on a programmable level. It is
connected to the Interrupt Request Channel 6 (IRQ #6) of the FGA-002
Gate Array. Like all on-board interrupts, the interrupt priority level of the
LANCE may be selected by programming the FGA-002.
3.13.2.3 Summary of
the LANCE
Device AM7990
Access Address FEF8.0000
16
Access Mode Word Only
Interrupt Request Level Programmable
FGA-002 Interrupt Request Channel Local IRQ #6
3.13.3 The Am7992B
Serial
Interface
Adapter (SIA)
The Am7992B Serial Interface Adapter (SIA) is a Manchester
Encoder/Decoder compatible with IEEE-802.3 and Ethernet
specifications.
3.13.4 Features of the
Am7992B SIA
- Compatible with Ethernet/Cheapernet/IEEE-802.3 specifications
- Crystal controlled Manchester Encoder
- Manchester Decoder acquired clock & data within four bit times
with an accuracy of +/-3 ns
- Guaranteed carrier and collision detection squelch threshold limits
- Carrier/collision detected for inputs greater than -275 mV
- No carrier/collision for inputs less than -175 mV
- Input signal conditioning reject transient noise
- Transients <10 ns for collision detector inputs
- Transients <20 ns for carrier detector inputs
- Receiver decodes Manchester data with worst case +/-19 ns of
clock jitter (at 10 MHz)
- TTL compatible host interface
- Transmit ac/-0.01% (without adjustments)
3.13.4.1 The Am7992B
Transmitter
The transmitter encodes serial data coming from the LANCE into a
Manchester II Code. The output signal is sent onto the Ethernet cable. An
oscillator on the CPU board provides the 10 MHz reference frequency for
the LANCE.
SEE ALSO: For further details please refer to the Am7992B data sheet
in Section 4, ‘Circuit Schematics and Data Sheets,’ on page 115.
☞