TI380C25 Datasheet, PDF (23/71 Pages) Texas Instruments – TOKEN-RING COMMPROCESSOR

TI380C25
TOKEN-RING COMMPROCESSOR
Bit 11:
SPWS012 – JANUARY 1995
LBP — Local-Bus Priority
This bit controls the priority levels of devices on the local bus.
0 = No external devices (such as TI380FPA) are used with the TI380C25.
1 = An external device (such as TI380FPA) is used with the TI380C25. This allows the
external bus master to operate at the necessary priorities on the local bus.
If the system uses the TMS380SRA only, the bit must be set to 0. If the system uses both the
TMS380SRA and the TI380FPA, the bit must be set to 1.
Bit 12:
SINTEN — System-Interrupt Enable
This bit allows the host processor to enable or disable system-interrupt requests from the
TI380C25. The system-interrupt request from the TI380C25 is on SINTR / SIRQ. The following
equation shows how SINTR / SIRQ is driven. The table also explains the results of the states.
SINTR/ SIRQ = (PSDMAEN * SWHRQ * !SWHLDA) + (SINTEN * SYSTEM_INTERRUPT)
PSDMAEN SWHRQ SWHLDA SINTEN
1†
1
1
X
1†
1
0
X
1†
0
0
X
X
X
X
1
0
X
X
1
0
X
X
0
† _{The value on SHLDA / SBGR is ignored.}
SYSTEM
INTERRUPT
(SIFSTS
REGISTER)
X
X
X
1
0
X
RESULT
Pseudo DMA is active.
The TI380C25 generated a system interrupt for a pseudo DMA.
Not a pseudo-DMA interrupt
The TI380C25 generates a system interrupt.
The TI380C25 does not generate a system interrupt.
The TI380C25 cannot generate a system interrupt.
Bit 13:
PEN — Parity Enable
This bit determines whether data transfers within the TI380C25 are checked for parity.
0 = Data transfers are not checked for parity.
1 = Data transfers are checked for correct odd parity.
Bit 14 – 15:
NSELOUT0, NSELOUT0 1 — Network-Selection Outputs
The values in these bits control NSELOUT0 and NSELOUT1. These bits can be modified only
while the ARESET bit is set.
These bits can be used to software configure a TI380C25 as follows: NSELOUT0 should be
connected to TEST0 (TEST1 should be left unconnected and TEST2 should be tied high).
NSELOUT0 and NSELOUT1 are used to select network speed as shown below:
NSELOUT0
0
0
1
1
NSELOUT1
0
1
0
1
SELECTION
Reserved
16-Mbps token ring
Reserved
4-Mbps token ring
At power up, these bits are set corresponding to 16-Mbps token ring (NSELOUT1 = 1,
NSELOUT0 = 0).
• POST OFFICE BOX 1443 HOUSTON, TEXAS 77251–1443
23