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参数资料
| 型号： | COM20019ILJP |
| 厂商： | STANDARD MICROSYSTEMS CORP |
| 元件分类： | 微控制器/微处理器 |
| 中文描述： | 1 CHANNEL(S), 312.5K bps, LOCAL AREA NETWORK CONTROLLER, PQCC28 |
| 封装： | PLASTIC, LCC-28 |
| 文件页数： | 31/65页 |
| 文件大小： | 386K |
| 代理商： | COM20019ILJP |
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Cost Competitive ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM
SMSC COM20019I
Page 37
Rev. 09-25-07
DATASHEET
Figure 6.2 -
RAM BUFFER PACKET CONFIGURATION
6.4.2
Transmit Sequence
During a transmit sequence, the microcontroller selects a 256 or 512 byte segment of the RAM buffer and
writes into it. The appropriate buffer size is specified in the "Define Configuration" command. When long
packets are enabled, the COM20019I interprets the packet as either a long or short packet, depending on
whether the buffer address 2 contains a zero or non-zero value. The format of the buffer is shown in
Figure 8. Address 0 contains the Source Identifier (SID); Address 1 contains the Destination Identifier
(DID); Address 2 (COUNT) contains, for short packets, the value 256-N, where N represents the number
of information bytes in the message, or for long packets, the value 0, indicating that it is indeed a long
packet. In the latter case, Address 3 (COUNT) would contain the value 512-N, where N represents the
number of information bytes in the message. The SID in Address 0 is used by the receiving node to reply to
the transmitting node. The COM20019I puts the local ID in this location, therefore it is not necessary to
write into this location. Please note that a short packet may contain between 1 and 253 data bytes, while a
long packet may contain between 257 and 508 data bytes. A minimum value of 257 exists on a long
packet so that the COUNT is expressible in eight bits. This leaves three exception packet lengths which
do not fit into either a short or long packet; packet lengths of 254, 255, or 256 bytes. If packets of these
SID
DID
COUNT = 256-N
NOT USED
DATA BYTE 1
DATA BYTE 2
DATA BYTE N-1
DATA BYTE N
NOT USED
SID
DID
0
COUNT = 512-N
NOT USED
DATA BYTE 1
DATA BYTE 2
DATA BYTE N-1
DATA BYTE N
SHORT PACKET
FORMAT
LONG PACKET
FORMAT
ADDRESS
0
1
2
COUNT
255
511
N = DATA PACKET LENGTH
SID = SOURCE ID
DID = DESTINATION ID
(DID = 0 FOR BROADCASTS)
0
1
2
COUNT
511
3
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相关代理商/技术参数 |
参数描述 |
|---|---|
| COM20019I-LJP | 制造商:SMSC 制造商全称:SMSC 功能描述:Low Cost ARCNET(ANSI 878.1) Controller with 2k X 8 On-Board RAM |
| COM20019ILJP3V | 功能描述:网络控制器与处理器 IC ARCNET Contrllr RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| COM20019ILJPTR | 功能描述:网络控制器与处理器 IC Arcnet (ANSI 878.1) Controllr 2k x 8 Ram RoHS:否 制造商:Micrel 产品:Controller Area Network (CAN) 收发器数量: 数据速率: 电源电流（最大值）:595 mA 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:PBGA-400 封装:Tray |
| COM20019IP | 制造商:Rochester Electronics LLC 功能描述:- Bulk |
| COM20020 | 制造商:SMSC 制造商全称:SMSC 功能描述:COM20020 3.3V ULANC Universal Local Area Network Controller with 2K x 8 On-Board RAM |
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