 |
Electronic Components Datasheet Search |
|
|
Electronic Components Datasheet Search |
|
COM20019I Datasheet(PDF) 37 Page - SMSC Corporation |
|
||||||||||||||||||||||||||||||
COM20019I Datasheet(HTML) 37 Page - SMSC Corporation |
|
|
37 / 65 page  Low Cost ARCNET (ANSI 878.1) Controller with 2K x 8 On-Board RAM SMSC COM20019I Page 37 Rev. 03-07-06 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 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 |
Similar Part No. - COM20019I_06 |
|
Similar Description - COM20019I_06 |
|
|
Link URL |
| Privacy Policy |
| ALLDATASHEET.COM |
| Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
English ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
