COM20019I Datasheet, PDF (31/65 Pages) SMSC Corporation – Low Cost ARCNET(ANSI 878.1) Controller with 2k X 8 On-Board RAM

Low Cost ARCNET (ANSI 878.1) Controller with 2K x 8 On-Board RAM
Table 6.8 - Sub Address Register
BIT
7-3
2,1,0
BIT NAME
Reserved
Sub Address 2,1,0
SYMBOL
SUBAD
2,1,0
DESCRIPTION
These bits are undefined.
These bits determine which register at address 07 may be
accessed. The combinations are as follows:
SUBAD2 SUBAD1 SUBAD0 Register
0
0
0
Tentative ID \ (Same
0
0
1
Node ID \ as in
0
1
0
Setup 1 / Config
0
1
1
Next ID
/ Register)
1
0
0
Setup 2
1
0
1
Reserved
1
1
0
Reserved
1
1
1
Reserved
SUBAD1 and SUBAD0 are exactly the same as exist in the
Configuration Register. SUBAD2 is cleared automatically by
writing the Configuration Register.
BIT
BIT NAME
7
Reset
6
Command
Chaining Enable
5
Transmit Enable
Table 6.9 - Configuration Register
SYMBOL
RESET
CCHEN
TXEN
DESCRIPTION
A software reset of the COM20019I is executed by writing a
logic "1" to this bit. A software reset does not reset the
microcontroller interface mode, nor does it affect the
Configuration Register. The only registers that the software
reset affect are the Status Register, the Next ID Register,
and the Diagnostic Status Register. This bit must be
brought back to logic "0" to release the reset.
This bit, if high, enables the Command Chaining operation
of the device. Please refer to the Command Chaining
section for further details. A low level on this bit ensures
software compatibility with previous SMSC ARCNET
devices.
When low, this bit disables transmissions by keeping
nPULSE1, nPULSE2 if in non-Backplane Mode, and nTXEN
pin inactive. When high, it enables the above signals to be
activated during transmissions. This bit defaults low upon
reset. This bit is typically enabled once the Node ID is
determined, and never disabled during normal operation.
Please refer to the Improved Diagnostics section for details
on evaluating network activity.
SMSC COM20019I
Page 31
DATASHEET
Rev. 04-15-05