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3)
drives the DB(15-0) signals to their values simultaneous with the next REQ signal
negation; and
4)
holds the DB(15-0) signals valid for a minimum of one transmit hold time.
If the I/O signal is true (i.e., transfer to the INIT), to receive SPI information units the INIT shall:
1)
Read the value on the DB(15-0) signals within one receive hold time of the transition of
the REQ signal; and
2)
respond with an ACK signal assertion after each REQ assertion/negation pair.
If the I/O signal is false (i.e., transfer to the TARG) and the phase of the P1 signal indicates data is
valid, to transfer SPI information units the INIT:
1)
Shall wait until detecting a REQ assertion;
2)
shall drive the DB(15-0) signals to their values simultaneous with the next ACK signal
assertion;
3)
shall hold the DB(15-0) signals valid for a minimum of one transmit hold time;
4)
shall drive the DB(15-0) signals to their values simultaneous with the next ACK signal
negation; and
5)
shall hold the DB(15-0) signals valid for a minimum of one transmit hold time.
If the I/O signal is false (i.e., transfer to the TARG), to receive SPI information units the TARG:
1)
reads the value of the DB(15-0) signals within one receive hold time of the transition of
the ACK signal.
If write flow control is enabled and the current SPI data stream information unit is the last SPI data
stream information unit of the stream then:
1)
The TARG asserts the P_CRCA signal a minimum of a flow control transmit setup time
before the end of the last information unit and shall keep the P_CRCA signal asserted for
a flow control transmit hold time;
2)
The TARG does not assert the P_CRCA signal until a minimum of a flow control hold
time after the end of the previous information unit; and
3)
The TARG negates the P_CRCA signal a minimum of a flow control transmit setup time
before the start of the next information unit.
Note :
The earlier in a SPI data stream information unit that the TARG asserts the P_CRCA signal,
the better the INIT may manage data pre-fetch.
As a result of a SPI information unit always being an even number of transfers, the REQ and ACK
signals are negated both before and after the transmission of the SPI information unit.
C141-C011
1-83
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