
Chapter 15. Registers Page 15-25
15.5.10 GPIF Hold Time
For any transaction where the GPIF writes data onto FD[15:0], this register determines how long
the data is held. Valid choices are 0, ½ or 1 IFCLK cycle. This register applies to
any
data written
by the GPIF to FD[15:0], whether through a flow state or not.
For non-flow states, the hold amount is really just a delay of the normal (non-held) presentation of
FD[15:0] by the amount specified in HOLDTIME[1:0].
For flow states in which the GPIF is the master on the bus (FLOWSTB.SLAVE = 0), the hold
amount is with respect to the activating edge (see FLOW_MASTERSTB_EDGE) of Master Strobe
(which will be a CTL pin in this case).
For flow states in which the GPIF is the slave on the bus (FLOWSTB.SLAVE = 1), the hold amount
is really just a delay of the normal (non-held) presentation of FD[15:0] by the amount specified in
HOLDTIME[1:0] in reaction to the activating edge of Master Strobe (which will be a RDY pin in this
case). Note the hold amount is NOT
directly
with respect to the activating edge of Master Strobe in
this case. It is with respect to when the data would normally come out in response to Master Strobe
including any latency to synchronize Master Strobe.
In all cases, the data will be held for the desired amount even if the ensuing GPIF state calls for the
data bus to be tristated. In other words the FD[15:0] output enable will be held by the same amount
as the data itself.
Bits 1-0 HOLDTIME[1:0] GPIF Hold Time
00 = 0 IFCLK cycles
01 = ½ IFCLK cycle
10 = 1 IFCLK cycle
11 = Reserved
GPIFHOLDTIME E60C
b7 b6 b5 b4 b3 b2 b1 b0
0 0 0 0 0 0 HOLDTIME[1:0]
R R R R R R RW RW
0 0 0 0 0 0 0 0
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