COM20019I-DZD SMSC, COM20019I-DZD Datasheet - Page 14

• Manufacturer Part Number: COM20019I-DZD
• Description: IC CTRLR ARCNET 2KX8 RAM 28-PLCC
• Manufacturer: SMSC
• Series: ARCNETr

Specifications of COM20019I-DZD

• Controller Type: ARCNET Controller
• Interface: Differential
• Voltage - Supply: 4.5 V ~ 5.5 V
• Current - Supply: 20mA
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 28-PLCC
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 638-1000-5

4.6.4
4.6.5
Rev. 09-25-07
Acknowledgements
An Acknowledgement is used to acknowledge reception of a packet or as an affirmative response to FREE
BUFFER ENQUIRIES and is sent by the following sequence:
Negative Acknowledgements
A Negative Acknowledgement is used as a negative response to FREE BUFFER ENQUIRIES and is sent
by the following sequence:
BURST
ALERT
An ALERT BURST
An SOH (Start Of Header--ASCII code 01H)
An SID (Source ID) character
Two (repeated) DID (Destination ID) characters
A single COUNT character which is the 2's complement of the number of data bytes to follow if a
short packet is sent, or 00H followed by a COUNT character if a long packet is sent.
N data bytes where COUNT = 256-N (or 512-N for a long packet)
Two CRC (Cyclic Redundancy Check) characters. The CRC polynomial used is: X
An ALERT BURST
An ACK (ACKnowledgement--ASCII code 86H) character
An ALERT BURST
A NAK (Negative Acknowledgement--ASCII code 15H) character
SOH
SID
DID
ALERT BURST
ALERT BURST
DATASHEET
DID
Page 14
Cost Competitive ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM
COUNT
ACK
NAK
data
data
CRC
16
CRC
+ X
SMSC COM20019I
15
+ X
2
+ 1.