TI380C30 Datasheet, PDF (10/78 Pages) Texas Instruments – INTEGRATED TOKEN-RING COMMPROCESSOR AND PHYSICAL-LAYER INTERFACE

TI380C30
INTEGRATED TOKEN-RING
COMMPROCESSOR AND PHYSICAL-LAYER INTERFACE
SPWS016A – NOVEMBER 1994 – REVISED JULY 1995
Pin Functions (Continued)
PIN
NAME
NO.
I/O/E†
DESCRIPTION
SBRLS
System-bus release. SBRLS indicates to the TI380C30 that a higher-priority device requires the
system bus. The value on SBRLS is ignored when the TI380C30 is not performing DMA. SBRLS is
internally synchronized to SBCLK.
67
I
H = The TI380C30 can hold onto the system bus (see Note 1).
L = The TI380C30 should release the system bus upon completion of current DMA cycle. If the
DMA transfer is not yet complete, the SIF rearbitrates for the system bus.
System-chip select. SCS activates the system interface of the TI380C30 for a DIO read or write.
SCS
66
I
H = Not selected (see Note 1)
L = Selected
SDBEN
System data-bus enable. SDBEN signals to the external data buffers to begin driving data. SDBEN
is activated during both DIO and DMA.
95
O
H = Keep external data buffers in the high-impedance state
L = Cause external data buffers to begin driving data
SDDIR
System data direction. SDDIR provides to the external data buffers a signal indicating the direction in
which the data is moving. During DIO writes and DMA reads, SDDIR is low (data direction is into the
TI380C30). During DIO reads and DMA writes, SDDIR is high (data direction is out from the TI380C30).
When the system interface is not involved in a DIO or DMA operation, SDDIR is high by default.
75
O
DATA
SDDIR DIRECTION DIO DMA
H
output
read write
L
input
write read
Intel Mode
SHLDA is used for system-hold acknowledge. SHLDA indicates that the system
DMA-hold request has been acknowledged. SHLDA is internally synchronized to
SBCLK (see Note 1).
SHLDA / SBGR ⁷⁴
H = Hold request acknowledged
I
L = Hold request not acknowledged
Motorola
Mode
SBGR is used for system bus grant. SBGR is an active-low bus grant, as defined in the
standard 68xxx interface, and is internally synchronized to SBCLK (see Note 1).
H = System bus not granted
L = System bus granted
SHRQ / SBRQ
93
SHRQ is used for system-hold request. SHRQ is used to request control of the system
bus in preparation for a DMA transfer. SHRQ is internally synchronized to SBCLK.
Intel Mode
H = System bus requested
L = System bus not requested
O
SBRQ is used for system-bus request. SBRQ is used to request control of the system
Motorola ^{bus in preparation for a DMA transfer. SBRQ is internally synchronized to SBCLK.}
Mode _{H = System bus not requested}
L = System bus requested
System-interrupt acknowledge. SIACK is from the host processor to acknowledge the interrupt request
from the TI380C30.
SIACK
61
I
H = System interrupt not acknowledged (see Note 1)
L = System interrupt acknowledged: The TI380C30 places its interrupt vector onto the system
bus.
† _{I = input, O = output, E = provides external-component connection to the internal circuitry for tuning}
NOTE 1: Pin has an internal pullup device to maintain a high-voltage level when left unconnected (no etch).
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