COM20020I Datasheet, PDF (31/72 Pages) SMSC Corporation – 5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM

5Mbps ARCNET (ANSI 878.1) Controller with 2K x 8 On-Chip RAM
Datasheet
BIT
BIT NAME
7 Receiver
Inhibited
6,5 (Reserved)
4 Power On Reset
3 Test
2 Reconfiguration
1 Transmitter
Message
Acknowledged
0 Transmitter
Available
Table 6.3 - Status Register
SYMBOL
RI
POR
TEST
RECON
TMA
TA
DESCRIPTION
This bit, if high, indicates that the receiver is not enabled because either
an "Enable Receive to Page fnn" command was never issued, or a packet
has been deposited into the RAM buffer page fnn as specified by the last
"Enable Receive to Page fnn" command. No messages will be received
until this command is issued, and once the message has been received,
the RI bit is set, thereby inhibiting the receiver. The RI bit is cleared by
issuing an "Enable Receive to Page fnn" command. This bit, when set,
will cause an interrupt if the corresponding bit of the Interrupt Mask
Register (IMR) is also set. When this bit is set and another station
attempts to send a packet to this station, this station will send a NAK.
These bits are undefined.
This bit, if high, indicates that the COM20020ID has been reset by either a
software reset, a hardware reset, or writing 00H to the Node ID Register.
The POR bit is cleared by the "Clear Flags" command.
This bit is intended for test and diagnostic purposes. It is a logic "0" under
normal operating conditions.
This bit, if high, indicates that the Line Idle Timer has timed out because
the RXIN pin was idle for 41μS. The RECON bit is cleared during a "Clear
Flags" command. This bit, when set, will cause an interrupt if the
corresponding bit in the IMR is also set. The interrupt service routine
should consist of examining the MYRECON bit of the Diagnostic Status
Register to determine whether there are consecutive reconfigurations
caused by this node.
This bit, if high, indicates that the packet transmitted as a result of an
"Enable Transmit from Page fnn" command has been acknowledged.
This bit should only be considered valid after the TA bit (bit 0) is set.
Broadcast messages are never acknowledged. The TMA bit is cleared by
issuing the "Enable Transmit from Page fnn" command.
This bit, if high, indicates that the transmitter is available for transmitting.
This bit is set when the last byte of scheduled packet has been
transmitted out, or upon execution of a "Disable Transmitter" command.
The TA bit is cleared by issuing the "Enable Transmit from Page fnn"
command after the node next receives the token. This bit, when set, will
cause an interrupt if the corresponding bit in the IMR is also set.
SMSC COM20020I Rev D
Page 31
DATASHEET
Revision 12-05-06