Sif adapter control register (sifacl) – Texas Instruments TMS380C26 User Manual
Page 26
TMS380C26
NETWORK COMMPROCESSOR
SPWS010A–APRIL 1992–REVISED MARCH 1993
POST OFFICE BOX 1443
•
HOUSTON, TEXAS
77251–1443
26
SIF Adapter Control Register (SIFACL)
The SIFACL register allows the host processor to control and to some extent reconfigure the
TMS380C26 under software control.
SIFACL Register
Bit #
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
T
E
S
T
0
T
E
S
T
1
T
E
S
T
2
—
SWHLDA
SWDDIR
SWHRQ
PSDMAEN
ARESET
CPHALT
BOOT
RES0
SINTEN
PEN
NSEL
OUT0
NSEL
OUT1
R
R
R
RP – 0
R – u
R – 0
RS – 0
RW – 0
RP – b
RP – b
R
RW – 1
RP – p
RP-0
RP–1
R = Read, W = Write, P = Write during ARESET = 1 only, S = Set Only,
– n = Value after reset
(b = Value on BTSTRP pin, p = Value on PRTYEN pin, u = Indeterminate)
Bits 0-2:
TEST (0 – 2). Value on TEST (0 – 2) pins.
These bits are read only and always reflect the value on the corresponding device pins. This
allows the host S/W to determine the network type and speed configuration. If the network speed
and type are software configurable, these bits can be used to determine which configurations
are supported by the network hardware.
TEST0
TEST1
TEST2
Description
L
L
H
Reserved
L
H
H
16 Mbps token ring
H
L
H
Ethernet (802.3/Blue Book)
H
H
H
4 Mbps token ring
X
X
0
Reserved
Bit 3:
Reserved. Read data is indeterminate.
Bit 4:
SWHLDA — Software Hold Acknowledge
This bit allows the SHLDA/SBGR pin’s function to be emulated from software control for
pseudo-DMA.
PSDMAEN
SWHLDA
SWHRQ
RESULT
0
†
X
X
SWHLDA value in the SIFACL register cannot be set to a one.
1
†
0
0
No pseudo-DMA request pending.
1
†
0
1
Indicates a pseudo-DMA request interrupt.
1
†
1
X
Pseudo-DMA process in progress.
† The value on the SHLDA/SBGR pin is ignored.
Bit 5:
SWDDIR — Current SDDIR Signal Value
This bit contains the current value of the pseudo-DMA direction. This enables the host to easily
determine the direction of DMA transfers, which allows system DMA to be controlled by system
software.
0
=
Pseudo-DMA from host system to TMS380C26.
1
=
Pseudo-DMA from TMS380C26 to host system.