COM20020-5 Datasheet, PDF (7/58 Pages) SMSC Corporation – Universal Local Area Network Controller with 2K x 8 On-Board RAM

Reconfigure
Timer has
Timed Out
Power On
Send
Reconfigure
Burst
Read Node ID
Write ID to
RAM Buffer
1
Set NID=ID
Start
Reconfiguration
Timer (420 mS)
Y
Invitation
N
to Transmit to
this ID?
N
Y
TA?
Broadcast?
N
Y
Send
Packet
Transmit
NAK
Transmit
ACK
Y
Was Packet
Broadcast?
Y
Y _RI?
Free Buffer
Enquiry to
this ID?
N
N
Y
N
SOH?
Y
N
RI?
Write SID
to Buffer
Transmit
Free Buffer
Enquiry
No
Activity
Y
DID ^Y
=0?
N
for
Y
N ^37u.s3?5
N
Broadcast ^N
ACK?
DID
Enabled?
=ID?
Y
N
NAK?
Set TA
YN
Y
N
No
Activity
Y
for
3u7s.3?5
N
Set TA
N
Y
ACK?
Set TMA
1
Increment
NID
Y
No
Activity
for
3u7s.3?5
Write Buffer
with Packet
Pass the
Token
CRC N
N
OK?
Y
LENGTH ^N
OK?
Y
- ^{ID refers to the identification number of the ID assigned to this node.}
- ^{NID refers to the next identification number that receives the token after}
after this ID passes it.
- ^{SID refers to the source identification.}
- DID refers to the destination identification.
- ^{SOH refers to the start of header character; preceeds all data packets.}
Y
DID
=0?
N
DID ^N
=ID?
Y
SEND ACK
Set RI
No Activity ^N
for 41
uS?
Y
Set NID=ID
Start Timer:
T=(255-ID)
x 73 us
Activity Y
On Line?
N
N
T=0?
Y
FIGURE 1 - COM20020-5 OPERATION
7