PDSP16488A MA
INPUT
4
4
B3 = 1
B3 = 1
delays
N th DEVICE IN THE ROW
delays
0
0
D3:2 = 00
D3:2 = 00
delays
delays
WIDTH = S
WIDTH = S
line
delays
line
delays
4 clock
delay
4 clock
delay
0/4
delays
0
ZERO
delays
0 IF S = 4, 4 IF S = 8
4 clock
delay
D0 = 0
D0 = 0 or 1
0
0
B3 = 0
N th DEVICE IN THE ROW
B3 = 0
delays
delays
D
D
D = 4+S(N-1) Defined by D3:2
WIDTH = S
D = 4+S(N-1) Defined by D3:2
WIDTH = S
delays
delays
line
delays
line
delays
4 clock
delay
4 clock
delay
0
0/4
delays
delays
0 IF S = 4, 4 IF S = 8
4 clock
delay
D0 = 0
D0 = 0 OR 1
0
0
B3 = 0
B3 = 0
N th DEVICE IN THE ROW
delays
delays
D
D = 4+S(N-1) Defined by D3:2
WIDTH = S
D
D = 4+S(N-1) Defined by D3:2
WIDTH = S
delays
delays
line
delays
line
delays
4 clock
delay
4 clock
delay
0/4
delays
0
OUTPUT
delays
0 IF S = 4,4 IF S = 8
D0 = 0
D0 = 0 OR 1
Fig. 6. Multi-Device Delay Paths
of 4 pixels in the inter device connection, and the
PDSP16488A thus only needs an option to delay the
expansion input by an additional four pixels.
The data from the last device in a horizontal row of
convolvers feeds the expansion input of the first device in the
nextrow. ThisisshowninFigure6. Withthisarrangement, the
position of the partial window as illustrated, is the inverse of
its vertical position on a normal TV screen. Thus the top, left
hand, device corresponds to the bottom, left hand, portion of
the complete window.
DELAY COMPENSATION FOR LARGE WINDOWS
A large window is composed of several partial windows
each of which is implemented in an individual device. If
necessary the partial window must be padded with zero
coefficients to become one of the standard sizes. When
constructing a large window it is necessary to delay the
expansiondatainputsinordertocompensateforgrowthinthe
horizontal direction. Delays in the partial sums are also
necessary to compensate for the total pipeline delay needed
to produce the previous complete horizontal stripe.
The output from the last device in the row is delayed
with respect to the original data input by an amount given by
the formula;
Within each device in a horizontal stripe, apart from
the first, the expansion input must be delayed by the width of
the partialwindow,beforeitisaddedtotheinternalsum.Since
partial windows can only be 4 or 8 pixels wide,a delay of 4 or
8 pixel clocks is needed. There is, however, an in-built delay
DELAY = 4 + [N-1].S where N is the number of devices in
a row and S is the partial window width, ie 4 or 8.
8
MITEL [ MITEL NETWORKS CORPORATION ]
