Cirrus Logic AN205 User Manual

Cs8900a frequently asked questions

 Cirrus Logic, Inc. 2002

Cirrus Logic, Inc.
P.O. Box 17847, Austin, Texas 78760
(512) 445 7222 FAX: (512) 445 7581
http://www.cirrus.com

AN205

Application Note

CS8900A FREQUENTLY ASKED QUESTIONS

1) Application Note 181 says that interrupts are not supported in 8-bit mode. Is this really true?

Yes, interrupts are NOT supported in 8-bit mode. They might appear to work for a while but will
eventually fail.

2) What free TCP/IP software does Cirrus Logic provide for use with the CS8900A?

None. Some recommended sources for TCP/IP are US Software, and Interniche,

http://www.lantronix.com/products/esw/index.html

and

http://www.iniche.com/products/tcpip.htm

Both have products that are compatible with the CS8900A.

3) I see that the CS8900A has I/O mode and Memory Mode. Is there a performance advantage to using

Memory Mode?

I/O Mode is 99.6% as fast as Memory Mode. Also, since the CS8900A defaults to I/O AND you don't
need glue logic in most systems in I/O Mode, Cirrus Logic recommends the use of the I/O mode.

4) I just got my boards back and I want to verify operation of the CS8900A. What do I do?

Follow these steps:

a)Plug in a 10BaseT cable from the RJ-45 on your device to a hub. Check for a link light on both

sides.

b)Read the Packet Page Data Port (Offset 0xC from the CS8900A base address in your system, I/O

Mode). You should get 0x0E63 or 0x630E (depending on byte ordering of your processor).

c)Write 0x0102 to Packet Page Pointer Port (Offset 0xA).

d)Read the Packet Page Data Port. You should get 0x3.

5) When I read from the CS8900A I get data that is not intelligible.

Download the application note, Crystal LAN

™

CS8900A Ethernet Controller Technical Reference

Manual, (AN83), at

http://www.cirrus.com/pubs/an83.pdf?DocumentID=260

from the Cirrus web

site. Check your schematic against the schematic checklist on page 4. If there is no link light (see item
4) then you have a hardware problem since the CS8900A should link with just power on.

Also, check your timing. TIOR2, TIOR3, TIOW2 and TIOW3 are the key timing parameters you must
meet. For example -- You must provide 10 ns of address/AEN stable before IOR# goes active.

6) What is the input and output capacitance of the CS8900A pins?

Input Capacitance CIN Max =10 pF

Output Capacitance COUT Max = 20 pF

AUG ‘02

AN205REV2