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
Cirrus Logic, Inc.
P.O. Box 17847, Austin, Texas 78760
(512) 445 7222 FAX: (512) 445 7581
http://www.cirrus.com
Copyright Cirrus Logic, Inc. 2002
(All Rights Reserved)
AUG ‘02
AN205REV2
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AN205
Input/Output Capacitance CIO Max = 20 pF
7) I need the algorithm to program the Hash Table Filter.
You can download a sample program from the CS8900A drivers page. Go to the Cirrus web site,
http://www.cirrus.com/Drivers/ethernet/ethernet.cfm. Download hash.zip.
8) What are Theta J/A and Theta J/C for the CS8900A?
Theta J/A = 34.9 C/w (0 ms air flow) Nominal
Theta J/C = 12.8 C/w (0 ms air flow) Nominal
9) Does Cirrus supply MAC addresses?
No. You need to get MAC address from IEEE. Paste the following link in your browser window:
http://standards.ieee.org/regauth/oui/index.shtml to apply for a company identifier from IEEE. A
MAC address (sometimes called an Individual Address) is made up of a 3 byte company identifier and
a 3 byte number assigned by the company.
That is IEEE will give your company a unique 3 byte number. Then for every device manufactured
your company will assign the last 3 bytes of the number.
10) Do I need an EEPROM in my design?
No. When there is no EEPROM then the CS8900A will default to I/O Base Address 0x0300. You will
need to store the MAC address somewhere in FLASH or other non-volatile memory.
11) Do you have a sample connection diagram for my processor?
There are several connection diagrams shown in the application note, Crystal LAN™ CS8900A
Ethernet Controller Technical Reference Manual, (AN83) at
http://www.cirrus.com/pubs/an83.pdf?DocumentID=260. These include a 68302, ARM 7 and Hitachi
SH3. There are so many processors that it is impossible to have a sample for every one. Please read
“CS8900A: Connecting to non-ISA Bus Systems” in Application Note 83.
12) What is the MTBF for the CS8900A?
We have Op-Life qualification data for rev B, C, and, D of CS8900A.
Rev B: 1161 devices, 500 hours, 0 failure. → 26 FIT → 38,400,000 MTBF
Rev C: 315 devices, 168 hours, 0 failure. → 280 FIT → 3,570,000 MTBF
Rev D: 315 devices, 168 hours, 0 failure. → 280 FIT → 3,570,000 MTBF
Rev C/D combined: 730 devices, 168 hours, 0 failures. → 140 FIT → 7,140,000 MTBF
Rev B has much better FIT result because the production qualification plan for rev C/D did not require
as high of a sample size and stress duration.
There were only minor metal revision changes from Rev B to Rev D. Rev D is the current shipping
version.
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