Cirrus Logic AN83 - Manual (Page 12)

AN83
12 AN83REV3
in BIOS. If the designer intends to use Cirrus sup-
plied drivers and does not use an EEPROM or store
driver configuration data in BIOS, then Cirrus sup-
plied drivers must be modified by the designer.
We recommend that the system store the individual
IEEE MAC address in a non-volatile memory
somewhere in the system, and that the end-user of
the system not be allowed to create an arbitrary ad-
dress. In a LAN, the existence of network nodes
that use the same MAC address will cause severe
network problems including destruction of data and
failure of various network nodes.
Design Example: CS8900A Interface to
Cirrus Logic CL-PS7211
This design is similar to the MC68302 except that
only the I/O mode data access is supported. This
completely elimiates glue logic. See Figure 4. The
highlights of the design are:
- CS8900A I/O space mapped into 7211 memory
- 3 address lines
- A8 and A9 tied high
- AEN used as active low chip select
- SBHE tied to 7211 chip select
- Only 16 bit accesses
Design Example: CS8900A Interface to
Hitachi SH3
This design is almost identical to the CL-PS7211
connection diagram. It uses I/O mode only, elimi-
nating glue logic. See Figure 5. The highlights of
the design are:
- CS8900A I/O space mapped into SH3 memory
- 3 address lines - A0 is tied to ground.
- A8 and A9 tied high
- AEN used as active low chip select
- SBHE tied to SH3 chip select
- Inverter on the IRQ line.
- Only 16 bit accesses
Summary
The CS8900A can be interfaced to most non-ISA
system with very minimum or no external logic.
This allows a low cost, small size and very efficient
Ethernet solution for non-ISA systems. Cirrus
Logic will provide support for non-ISA designs,
including logic schematic review and layout review
for design engineers. Those reviews help prevent
logic errors, and help to minimize EMI emissions.