S2020/S2021
HIPPI SOURCE/DESTINATION INTERFACE CIRCUITS
HIPPI DATA CONTROL
SELECT_0, 1, 2 (bi-directional) [SELBx]
These signals are used in conjunction with the
MODE_SELECT inputs during manufacturing testing to
confirm the function of the internal counters and state
machines. In the functional mode [Mode value 5 (101)]
the value of the SELECT (SELECT_2 is MSB) bus
indicates the type of data available on the DOUT_0,31
signals. Select value 0 (000) indicates burst data on
the outputs. Select value 1 (001) indicates I-Field data
on the outputs. Select value 2 (010) indicates the LLRC
word, and Select value 3 (011) indicates internal status
data during inter-BURST wait states. When there is no
connection on the HIPPI channel, the select value will
sequence and repeat 5,6,7 (101, 110, 111) until
connection is requested. Select value 4 is reserved to
indicate sequence error status for advanced link
diagnostics. For most applications these latter values
can be ignored.
The data and control signals, received on the HIPPI
channel, are resynchronized to the 25_MHz local
clock, converted to TTL, and then presented to the
data and control interface used by the host.
The HIPPI data control signals are:
BURST_OUT (output) [BROUT]
This signal indicates the state of the BURST line on
the HIPPI channel. High indicates an active BURST
and is presented with each word of the received
burst. Low indicates an inactive BURST and is
presented when there is no received data.
PACKET_OUT (output) [PKOUT]
This signal indicates the state of the PACKET line on
the HIPPI channel. High indicates an active PACKET
and is presented as long as PACKET is active on the
HIPPI channel. Low indicates an inactive PACKET
and is presented as long as PACKET is inactive on
the HIPPI channel.
DATA_VALID (output) [DTVAL]
This signal is intended to be used together with the
SELECT_0,1,2 outputs to gate the clocking of received
data into the FIFO or register set selected by the select
lines. All received data will be presented to the data
outputs of the Destination device and will be
accompanied by a DATA_VALID signal.
Note: The BURST_OUT and PACKET_OUT signals
are provided to delimit the data into the FIFO the
same way it is delimited on the HIPPI channel.
These signals may not be needed by the Host.
FIFO Control Signal Table
SELB(2:0)
HOST data
HIPPI Burst
HIPPI I-Field
HIPPI LLRC
DATA_VALID
1 (high)
1 (high)
1 (high)
1 (high)
1 (high)
1 (high)
0 (low)
Comment
000
for duration of data received Burst
001
for duration of HIPPI Connect Request
010
one word, after last word of each Burst
one word, beginning each Packet received on channel (accomp. start of PACKET_OUT)
one word, end of each Burst, after LLRC*
011
gen. op. status
one word, end of each Packet (accompanies deactivation of PACKET_OUT)*
multiple words, while connection is estab. across channel, but channel has no data
011
100
gen. op. status
SEQUENCE
ERROR
one word, when a HIPPI sequence error is detected, or when an illegal signal sequence
disrupts the devices's state machines
1 (high)
1 (high)
1 (high)
1 (high)
one word, in sequence with FLOW status words (below), continuously while channel is
disconnected
101
110
111
idle/disab. status
FLOW status
word 1
one word, in sequence with FLOW status word 2 and idle/disab. status, continuously while
channel is disconnected
FLOW status
word 2
one word, in sequence with FLOW status word 1 and idle/disab. status, continuously while
channel is disconnected
*Only one general operational status word (Select code 011) will be presented if the BURST and PACKET terminations coincide, i.e., BURST deasserted,
followed by PACKET deasserted.
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AMCC [ APPLIED MICRO CIRCUITS CORPORATION ]
