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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  
The first word of each group is referred to as the 3.4.5 Reset Configuration Block Checksum  
Group Header. The Group Header indicates the  
number of words in the group and the address of the  
PacketPage register into which the first data word  
in the group is to be loaded. Any remaining words  
in the group are stored in successive PacketPage  
registers.  
A checksum is stored in the high byte position of  
the word immediately following the last group of  
data in the Reset Configuration Block. (The EE-  
PROM address of the checksum value can be deter-  
mined by dividing the value stored in the Link Byte  
by two). The checksum value is the 2’s comple-  
ment of the 8-bit sum (any carry out of eighth bit is  
ignored) of all the bytes in the Reset Configuration  
Block, excluding the checksum byte. This sum in-  
cludes the Reset Configuration Block header at ad-  
dress 00h. Since the checksum is calculated as the  
2’s complement of the sum of all preceding bytes in  
the Reset Configuration Block, a total of 0 should  
result when the checksum value is added to the sum  
of the previous bytes.  
3.4.4.1 Group Header  
Bits F through C of the Group Header specify the  
number of words in each group that are to be trans-  
ferred to PacketPage registers (see Figure 4). This  
value is two less than the total number of words in  
the group, including the Group Header. For exam-  
ple, if bits F through C contain 0001, there are three  
words in the group (a Group Header and two words  
of configuration data).  
3.4.6 EEPROM Example  
First Word of a Group of Words  
Table 6 shows an example of a Reset Configuration  
Block stored in a C46 EEPROM. Note that little-  
endian word ordering is used, i.e., the least signifi-  
cant word of a multiword datum is located at the  
lowest address.  
F
E D C B A 9 8 7 6 5 4 3 2 1 0  
3.4.7 EEPROM Read-out  
If the EEDI pin is asserted high at the end of reset,  
the CS8900A reads the first word of EEPROM data  
by:  
0
0
0
Number of Words  
in Group  
9-bit PacketPage Address  
1) Asserting EECS  
2) Clocking out a Read-Register-00h command  
on EEDO (EESK provides a 1MHz serial clock  
signal)  
Figure 4. Group Header  
Bits 8 through 0 of the Group Header specify a 9-  
bit PacketPage Address. This address defines the  
PacketPage register that will be loaded with the  
first word of configuration data from the group.  
Bits B though 9 of the Group Header are forced to  
0, restricting the destination address range to the  
first 512 bytes of PacketPage memory. Figure 4  
shows the format of the Group header.  
3) Clocking the data in on EEDI.  
If the EEDI pin is low at the end of the reset signal,  
the CS8900A does not perform an EEPROM read-  
out (uses its default configuration).  
3.4.7.1 Determining EEPROM Size  
The CS8900A determines the size of the EEPROM  
by checking the sense of EEDI on the tenth rising  
edge of EESK. If EEDI is low, the EEPROM is a  
CIRRUS LOGIC PRODUCT DATA SHEET  
DS271PP3  
23  
 
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