DP83936AVF NSC [National Semiconductor], DP83936AVF Datasheet - Page 66

• Manufacturer Part Number: DP83936AVF
• Description: Full Duplex SONICTM-T Systems-Oriented Network Interface Controller with Twisted Pair Interface
• Manufacturer: NSC [National Semiconductor]

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7 0 Bus Interface
7 3 5 5 Memory Cycle for BMODE
Asynchronous Mode
On the rising edge of T1 the SONIC-T asserts ADS and
ECS to indicate that the memory cycle is starting The ad-
dress (A31 –A1) bus status (S2–S0) and the direction
strobe (MWR) are driven and do not change for the remain-
der of the memory cycle On the falling edge of T1 the
SONIC-T deasserts ECS ADS is deasserted on the rising
edge of T2
In Asynchronous mode RDYi is asynchronously sampled
on the falling edge of both T1 and T2 RDYi does not need
to be synchronized to the bus clock because the chip al-
ways resolves these signals to either a high or low state
Meeting the setup time for RDYi guarantees that the
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FIGURE 7-14 Memory Read BMODE
FIGURE 7-15 Memory Read BMODE
(Continued)
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SONIC-T will terminate the memory cycle 1 5 bus clocks
after RDYi was sampled T2 states will be repeated until
RDYi is sampled properly in a low state (see note below)
During read cycles ( Figures 7-14 and 7-15 ) data (D31– D0)
is latched at the falling edge of T2 and DS is asserted at the
rising edge of T1 For write cycles ( Figures 7-16 and 7-17 )
data is driven on the falling edge of T1 If there are wait
states inserted DS is asserted on the rising edge of the first
T2 (wait) DS is not asserted for zero wait state write cycles
The SONIC-T terminates the memory cycle by deasserting
DS at the falling edge of T2
Note If the setup time for RDYi is met during T1 the full asynchronous bus
0 Asynchronous (1 Wait-State)
0 Asynchronous (2 Wait-State)
cycle will take only 2 bus clocks This may be an unwanted situation
If so RDYi should be deasserted during T1
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TL F 12597 – 42