
EZ-USB FX2 Technical Reference Manual
Page 10-18 EZ-USB FX2 Technical Reference Manual v2.1
In Figure 10-8, the GPIF remains in S1 until the RDY0 signal goes low, then branches to S2.
Figure 10-9 illustrates the GPIF behavior when the RDY0 signal is
already
low when S1 is
entered: The GPIF branches to S2.
Although it appears in Figure 10-8 that the GPIF branches
immediately
from State 0 to State 2,
this isn’t exactly true. Even if RDY0 is already low before the GPIF enters State 1, the GPIF
spends one IFCLK cycle in State 1.
10.3.3 Re-Executing a Task Within a DP State
In the simple DP examples shown earlier in this chapter, a control task (e.g., output a word on
FD[15:0] and increment GPIFADR[8:0]) executes only once at the start of a DP State, then the
GPIF waits, sampling a RDYx input repeatedly until that input “tells” the GPIF to branch to the next
State.
The GPIF also has the capability to re-execute the control task every time the RDYx input is sam-
pled; this feature can be used to burst a large amount of data without passing through the Idle
State.
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