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CS8900A-IQ 参数 Datasheet PDF下载

CS8900A-IQ图片预览
型号: CS8900A-IQ
PDF下载: 下载PDF文件 查看货源
内容描述: 水晶局域网? ISA以太网控制器 [Crystal LAN ⑩ ISA Ethernet Controller]
分类和应用: 控制器局域网以太网
文件页数/大小: 128 页 / 1360 K
品牌: CIRRUS [ CIRRUS LOGIC ]
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CS8900A  
Crystal LAN™ ISA Ethernet Controller  
3.4 Configurations with EEPROM  
3.4.3.1 Reset Configuration Block Structure  
The Reset Configuration Block is a block of contig-  
uous 16-bit words starting at EEPROM address  
00h. It can be divided into three logical sections: a  
header, one or more groups of configuration data  
words, and a checksum value. All of the words in  
the Reset Configuration Block are read sequential-  
ly by the CS8900A after each reset, starting with  
the header and ending with the checksum. Each  
group of configuration data is used to program a  
PacketPage register (or set of PacketPage registers  
in some cases) with an initial non-default value.  
3.4.1 EEPROM Interface  
The interface to the EEPROM consists of the four  
signals shown in Table 5.  
CS8900A Pin  
(Pin #)  
EEPROM  
Pin  
CS8900A Function  
EECS (Pin 3) EEPROM Chip Select Chip Select  
EESK (PIN 4) 1 MHz EEPROM  
Serial Clock output  
Clock  
Data In  
Data Out  
EEDO (Pin 5) EEPROM Data Out  
(data to EEPROM)  
EEDI (Pin 6) EEPROM Data in  
(data from EEPROM)  
3.4.3.2 Reset Configuration Block Header  
Table 5. EEPROM Interface  
The header (first word of the block located at EE-  
PROM address 00h) specifies the type of EE-  
PROM used, whether or not a Reset Configuration  
block is present, and if so, how many bytes of con-  
figuration data are stored in the Reset Configura-  
tion Block.  
3.4.2 EEPROM Memory Organization  
If an EEPROM is used to store initial configuration  
information for the CS8900A, the EEPROM is or-  
ganized in one or more blocks of 16-bit words. The  
first block in EEPROM, referred to as the Configu-  
ration Block, is used to configure the CS8900A af-  
ter reset. An example of a typical Configuration  
Block is shown in Table 6. Additional blocks con-  
taining user data may be stored in the EEPROM.  
However, the Configuration Block must always  
start at address 00h and be stored in contiguous  
memory locations.  
3.4.3.3 Determining the EEPROM Type  
The LSB of the high byte of the header indicates  
the type of EEPROM attached: sequential or non-  
sequential. An LSB of 0 (XXXX-XXX0) indicates  
a sequential EEPROM. An LSB of 1 (XXXX-  
XXX1) indicates a non-sequential EEPROM. The  
CS8900A works equally well with either type of  
EEPROM. The CS8900A will automatically gen-  
erate sequential addresses while reading the Reset  
Configuration Block if a non-sequential EEPROM  
is used.  
3.4.3 Reset Configuration Block  
The first block in EEPROM, referred to as the Re-  
set Configuration Block, is used to automatically  
program the CS8900A with an initial configuration  
after a reset. Additional user data may also be  
stored in the EEPROM if space is available. The  
additional data are stored as 16-bit words and can  
occupy any EEPROM address space beginning im-  
mediately after the end of the Reset Configuration  
Block up to address 7Fh, depending on EEPROM  
size. This additional data can only be accessed  
through software control (refer to Section 3.5 on  
page 24 for more information on accessing the EE-  
PROM). Address space 80h to AFh is reserved.  
3.4.3.4 Checking EEPROM for presence of Reset  
Configuration Block  
The read-out of either a binary 101X-XXX0 or  
101X-XXX1 (X = do not care) from the high byte  
of the header indicates the presence of configura-  
tion data. Any other readout value terminates ini-  
tialization from the EEPROM. If an EEPROM is  
attached but not used for configuration, Crystal rec-  
ommends that the high byte of the first word be  
programmed with 00h in order to ensure that the  
CIRRUS LOGIC PRODUCT DATA SHEET  
DS271PP3  
21  
 
 
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